slide1 n.
Skip this Video
Loading SlideShow in 5 Seconds..
SP 6.5 : The student can evaluate alternative scientific explanations. PowerPoint Presentation
Download Presentation
SP 6.5 : The student can evaluate alternative scientific explanations.

Loading in 2 Seconds...

play fullscreen
1 / 48

SP 6.5 : The student can evaluate alternative scientific explanations. - PowerPoint PPT Presentation

  • Uploaded on

LO 3.1 : The student is able to construct scientific explanations that use the structures and mechanisms of DNA and RNA to support the claim that DNA and, in some cases, RNA are the primary sources of heritable information. SP 6.5 : The student can evaluate alternative scientific explanations.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'SP 6.5 : The student can evaluate alternative scientific explanations.' - ling

Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

LO 3.1: The student is able to construct scientific explanations that use the structures and mechanisms of DNA and RNA to support the claim that DNA and, in some cases, RNA are the primary sources of heritable information.

SP 6.5: The student can evaluate alternative scientific explanations.

Explanation: The storage of information is crucial for the cell to continue on and preform properly. In order for daughter cells to continue in their reproductive cycles and replications each cell has to receive genetic information from the parent cells. Genes from the parents are passed on to the offspring from segments of DNA and RNA which contain sequences of amino acids and proteins.The information needed is contained in the DNA. However viruses can have RNA as well as DNA, which is able to store information needed to pass on to the next generation. The unique structure of DNA allows it to form exact replications and pass them on to the next generation in the form of genetic information. This is due to the nucleotide sequences that for the DNA.

M.C. Question: Synthesis of a new DNA strand usually begins with?

A thymine dimer

DNA Primer

DNA Ligase

RNA Primer

Learning Log/FRQ-style Question: Describe the process of DNA replication and how sexual reproduction doesn’t produce identical offspring from the parent. Explain why changes occur in the DNA.


LO 3.2 The student is able to justify the selection of data from historical investigations that support the claim that DNA is the source of heritable information.

SP 4.1 The student can justify the selection of the kind of data needed to answer a particular scientific question.

Explanation: Many experiments were performed and analyzed on the path towards proving that DNA was the source of heritable information, but two are particularly associated with the discovery. The first was performed by Frederick Griffith. In his experiment, he used four mice to test for solutions. One contained live deadly bacteria, one live benign bacteria, one dead deadly bacteria, and one both dead deadly bacteria and live benign bacteria. He injected one of these solutions into four mice and observed the results. As expected, the one with the deadly bacteria died, and the ones with the benign bacteria and the dead bacteria lived, but the one with both live benign bacteria and dead deadly bacteria died. He concluded that some sort of genetic material exude from the dead bacteria and was incorporated by the live bacteria and caused it to be deadly. The only question left was what part of the cell was the genetic material. This question was solved by the Hershey/Chase experiment. They had found that bacteriophages consisted of only a protein shell and DNA, and that they caused bacteria to incorporate some part of them and produce more, just like Griffith’s bacteria. They then designed an experiment where two batched of bacteriophages were prepared. One was given a radioactive tracer that bonded with the protein shells and one was given a radioactive tracer that bonded with the DNA. The batches were then separately introduced to bacteria colonies and given time to insert their genetic material. The batches were then blended and centrifuged to get the cell pieces (including genetic material) to the bottom of the tubes. The tube with the tracers in the DNA showed it at the bottom of the tube meaning that DNA was what was incorporated into the bacteria cells and therefore what carried genetic information.

M.C. Question: DNA’s use as heritable information relies on:

Its nucleotide pairs

The phosphate backbone

Introns and exons

The codon order



L.O 3.2

Learning Log/FRQ style Question: DNA is often transferred between bacterial cells. Name three ways in which DNA can be transferred between two cells and explain how each works as a transfer of genetic information.


LO 3.3: The student is able to describe representations and models that illustrate how genetic information is copied for transmission between generations.

SP 1.2: The student can describe representations and models of natural or man-made

phenomena and systems in the domain.

Explanation: The cell cycle and DNA replication are responsible for passing on and copying genetic information between generations. During interphase of meiosis, the cell grows and copies its chromosomes containing genetic material. The first step in DNA replication is the unwinding of the double helix structure by the enzyme helicase. Single strand binding protein binds to and stabilizes the single stranded DNA. DNA polymerase III synthesizes the leading strand in the 5’ to 3’ direction while primase begins synthesis of the RNA primer for the Okazaki fragments. DNA polymerase III dissociates when it reaches the RNA primer on each fragment, then moves to the replication fork and adds DNA nucleotides to the 3’ end. DNA polymerase I removes the primer from the 5’ end and DNA ligase bonds the Okazaki fragments together. After interphase, meiosis I begins with the crossing over of chromosomes (DNA molecules) to form tetrads. During metaphase I, the tetrads line up in the middle of the cell and in anaphase I, the homologous chromosomes move toward opposite poles. Once there are two haploid cells, the chromosomes line up in the middle of the cell again and as the cell grows, the sister chromatids are separated- leaving four haploid daughter cells with genetic information that is not identical.

M.C. Question: Suppose there is a disorder which prevents

synapsis from taking place during meiosis. This would cause all

of the following EXCEPT

Four haploid cells containing identical genetic

information to be produced.

B) A decrease in genetic variation due to the inability

of a cleavage furrow to form.

The inability of chiasmata to hold the

homologues together in meiosis I.

D) Genetically identical sister chromatids of each

chromosomes in meiosis II.

Learning Log/FRQ- Style Question: Describe the role of the following in DNA replication: Helicase, Primase, DNA Ligase, DNA polymerase. Explain what happens to the chromosomes during the three stages of meiosis. Explain how crossing over causes genetic variation.


LO 3.4: The student is able to describe representations and models illustrating how genetic information is translated into polypeptides.

SP 1.2: The student can describe representations and models of natural or man-made phenomena and systems in the domain.

Explanation: Once transcription has occurred and the gene strand has been processed into mRNA, it leaves the nucleus and heads to the ribosome. At first the ribosome is made up of two parts- the small and large subunits- and they bind together as the mRNA binds to the small subunit, and the start codon (AUG) uses GTP to bind the large subunit. The large subunit has three main sights: E sight (where the tRNA Exits), P site (Peptidyl- tRNA binding sight), and the A site (Aminoacyl- tRNA binding site). The tRNA anti-codon matches with the complementary codon in the A site via the hydrolysis of GTP. An rRNA molecule of the large subunit catalyzes the formation of a peptide bond between the amino acid in the A site and the carboxyl end of the growing polypeptide in the P site (this attaches the polypeptide to the tRNA in the A site). The ribosome translocates the tRNA (by the use of more GTP) from the A site to P sites and the empty tRNA than was in the P site is moved to the E site and ejected from the ribosome to be recycled. These steps can be summarized as: codon recognition (anticodon to codon in the A site), peptide bond formation (from site P to A), and Translocation (the movement from site A to P to E). Once when a ribosome reaches a stop codon on mRNA, the A site accepts a protein called a release factor instead of tRNA. The release factor hydrolyses the bond between the tRNA in the

P site and the last amino acid of the polypeptide chain. The polypeptide is they freed from the

ribosome. The two ribosomal subunits and the other components of the assembly dissociate

leaving the ribosome ready for another round of translation.

M.C. Question: Suppose a protein were to be built incorrectly, thus creating a nonfunctional polypeptide. All of the following could be a cause EXCEPT:

There was an error as the GTP hydrolyzed anticodon and codon mismatched the wrong tRNA thus bonding the incorrect amino acid.

The mRNA strand had an error in the nucleotide sequence after transcription and RNA processing.

In the P site, the ATP failed in binding the amino acid from the incoming tRNA in the A site.

The mRNA strand had an error which caused the stop codon to be out of place, causing the protein to be longer than required.

FRQ: Draw and label a ribosome and its respective parts during translation. Describe the function of each element in the gene-to-polypeptide process.


LO 3.5: The student can justify the claim that humans can manipulate heritable information by identifying at least two commonly used technologies. SP 6.4: The Student can make claims and predictions about natural phenomena based on scientific theories and models. Explanation: Humans can manipulate heritable information in bacterium (gene cloning) with plasmids by insertion of foreign DNA into the plasmid. Then the host bacterium forms colonies of cells with the new gene of interest. Then these bacterium can be inserted into other organisms who need that gene. Such as the gene for pest resistance inserted into plants. Also Gene Therapy, the alteration of an afflicted individual’s genes, holds great potential for treating disorders traceable to a single defective gene. Gene Therapy can use a retrovirus as a vector that inserts a DNA transcript of its RNA genome into the chromosomal DNA of its host cell. If the foreign gene carried by the retroviral vector is expressed, the cell and its descendants will possess the gene product, and the patient will be cured. So humans can base the idea of DNA and RNA as the code for producing how organisms functions so they can survive. If the organism does not function normally, or can be used to do other tasks we can alter its genome in a way that it can function better. M.C. Question:Which of the following is not true about restriction enzymes?A. They protect bacterial cells against the introduction of DNA from other organismsby cutting up foreign DNAB. They create a site for a eukaryotic gene to be inserted into a bacterial plasmidC. They bind bacterial DNA fragments togetherD. They cut the sugar phosphate backbone of bacterial DNA to create sticky endsLearning Log/ FRQ-style Question: How could someone test to know if the specific gene is cloned correctly into the plasmid? Also, how could someone prepare large quantities of a particular gene or other DNA sequence using PCR and how would thisbe useful?


LO 3.6 The student can predict how a change in a specific DNA or RNA sequence can result in changes in gene expression.

SP 6.4 The student can make claims and predictions about natural phenomena based onscientific theories and models.

Explanation: In both DNA and RNA, there are sequences of 3 nucleotides on a strand called codons. Each codon codes for a specific gene that will later be expressed when the genes are coded for amino acids to make proteins. If a change in a sequence occurred, for example, if one nucleotide was taken out in a point mutation, this would result in a frame shift. When one nucleotide is taken out, the sequences on either side simply slide over. This, however, ends up changing every single codon on one side. Whatever protein the codons made before the mutation will have changed. Now during translation, the sequence of 3 nucleotides in each codon will be different. Now new proteins will be made and, therefore, express the change in the sequence of the gene.

M. C. Which of the following would cause the most change in gene expression?

  • A codon deletion in the middle of a coding sequence.
  • A base pair substitution at the beginning of a coding sequence.
  • A deletion of a single nucleotide in a coding sequence.
  • An insertion of a codon at the beginning of a sequence.

Learning Log/FRQ-style Question:

Sickle cell anemia is the result of a point mutation in the codon for glutamine in a DNA sequence. Describe the process of the point mutation causing the disease and how it leads to the expression of the disease.


LO 3.7 The student can make predictions about natural phenomena occurring during the cell cycle.

SP 6.4 The student can make claims and predictions about natural phenomena based on scientific theories and models.

Explanation: The cell cycle is a complex set of stages that is highly regulated with checkpoints, which determine the ultimate fate of the cell. Interphase consists of three phases: growth, synthesis of DNA, preparation for mitosis. Internal and external signals provide stop-and-go signs at the checkpoints. Mitosis alternates with interphase in the cell cycle. Mitosis passes a complete genome from the parent cell to daughter cellsand occurs after DNA replication.Mitosis followed by cytokinesis, produces two genetically identical daughter cells. Mitosis plays a role in growth, repair, and asexual reproduction. Meiosis, a reduction division, followed by fertilization ensures genetic diversity in sexually reproducing organisms. Meiosis ensures that each gamete receives one complete haploid (1n) set of chromosomes. During meiosis, homologous chromosomes are paired, with one homologue originating from the maternal parent and the other from the paternal parent. Orientation of the chromosome pairs is random with respect to the cell poles. Separation of the homologous chromosomes ensures that each gamete receives a haploid (1n) set of chromosomes composed of both maternal and paternal chromosomes. During meiosis, homologous chromatids exchange genetic material via a process called “crossing over,” which increases genetic variation in the resultant gametes. Fertilization involves the fusion of two gametes, increases genetic variation in populations by providing for new combinations of genetic information in the zygote, and restores the diploid number of chromosomes.

M.C. Question: Increases in the enzymatic activity of some protein kinases important for the regulation of the cell cycle are due to

a) Kinase synthesis by ribosomes

b) Activation of inactive kinases by binding to cyclins

c) Conversion of inactive cyclins  to active kinases by means of phosphorylation

d) Cleavage of the inactive kinase molecules by cytoplasmic proteases

A decline in external growth factors to a concentration below the inhibitory threshold

FRQ: The cell cycle is fundamental to the reproduction of eukaryotic cells.Explain

the role of THREE of the following in mitosis or cytokinesis.

  • Kinetochores
  • Microtubules
  • Motor proteins
  • Actin filaments

L.O. 3.8 The student can describe the events that occur in the cell cycle.

S.P. 1.2 The student can describe representations and models of natural or man-made

phenomena and systems in the domain.

The cell cycle is a series of events that allows an organism to grow through the production of more cells. The cycle is made of four stages, the G1 phase, a “gap” period of cell growth, the S phase of DNA replication, the G2 phase, a second “gap” period of growth and preparation for mitosis, and finally the mitotic (M) phase. Although the M phase is usually the shortest phase, it is the most critical. During the M phase, chromosomes condense (prophase), line up at the center of the cell (metaphase), and are pulled apart by the mitotic spindle fibers (anaphase). Two daughter nuclei then form (telophase) and the cells undergo cytokinesis. The two new daughter cells then enter the G1 phase. The cell cycle is regulated by three main checkpoints in the G1, G2, and M phases. These checkpoints are somewhat of a “stop” signal that halts the cell cycle until they are overridden by “go ahead” signals. Examples of such signals are maturation-promoting factors (MPFs), complexes of cyclins and Cdks that allow the cell to enter the M phase.

M.C. Question: What could be an effect on a cell if the binding of cyclin and CDK was inhibited?

a. The cell would enter the G0phase

b. The cell would be unable to enter the M phase and would be unable to divide.

c. Following division, Cdk would be unable to be recycled.

d. Apoptosis would occur immediately.

c. Both A and B

FRQ/LL Question:

The interactions between Cdk

molecules and cyclins are an

Important aspect of the cell cycle.

Discuss the interactions between these two molecules and their effects on the regulation of the cell cycle. Include an explanation of the effects on the cell if cyclins are produced in excess.


LO 3.9: The student is able to construct an explanation, using visual representations or narratives, as to how DNA in chromosomes is transmitted to the next generation via mitosis, or meiosis followed by fertilization.

SP 6.2: The student can construct explanations of phenomena based on evidence produced through scientific practices.

Explanation: Mitosis produces 2 daughter cells that are identical to the parent cell, and is prevalent in asexual reproduction. Mitosis also allows organisms to grow and develop and repair damaged cells. Meiosis produces gametes (sperm and egg) that have half the number of chromosomes as the parent cell; these gametes enable an organism to reproduce sexually.

Mitosis: Prior to mitosis, a cell grows and develops during interphase, during which a cell spends approximately 90% of its life cycle. During interphase the chromosomes are not yet visible, and the nuclear envelope is still present. At the end of interphase, each chromosome makes an identical copy of itself. The cell then enters the mitotic phase. During prophase, the chromosomes condense and centromeres begin to migrate to opposite sides of the cell. In metaphase, chromosomes line up down the middle of the cell and spindle fibers attach themselves to the chromosomes. During anaphase, the sister chromatids split apart before moving to opposite sides of the cell during telophase. Cytokinesis Is the last step, by which the cell is split down the middle forming 2 identical daughter cells, identical to the original parent cell.

Meiosis: Meiosis only occurs in the testes/ovaries, and it produces haploid gametes that unite to form a diploid zygote via fertilization. Meiosis, like mitosis, undergoes the same phases, only, meiosis undergoes each twice. Prior to meiosis 1, the cells paternal and maternal chromosomes are copied; these 4 resulting chromosomes line up during prophase 1 of meiosis 1 and are known as a tetrad. During meiosis 1 the tetrad splits and the germ line cell results in 2 different cells. Crossing over will usually occur during prophase 1; during this, DNA between maternal and paternal chromosomes gets swapped, which causes genetic variation amongst resulting gametes. After meiosis 1 is complete, the 2 resulting cells reproduce again via meiosis II, resulting in 4 overall gametes. Each gamete is different from each other due to crossing over and the law of independent assortment, which says that it is totally random as to how and in what order the tetrads line up. The resulting 4 gametes are then used to fertilize a gamete of the opposite sex to produce a zygote. All organisms undergo some form of meiosis except bacteria which only reproduce asexually.

MC: Which of the following would result after meiosis II of a germ line cell with 10 pairs of homologous chromosomes?

A.) 4 Gametes, each with 10 pairs of homologous chromosomes.

B.) 4 identical copies of the original germ line cell.

C.) 4 gametes, each with 10 chromosomes, 1 from each homologous pair.

D.) 2 gametes, each with 10 sister chromatids.


Describe 2 ways by which a newly fertilized zygote will have genetic variability. This offspring will not be genetically identical to any other offspring of the same parents-why?


LO 3.10: The student is able to represent the connection between meiosis and increased genetic diversity necessary for evolution

SP 7.1: the student can connect phenomena and models across spatial and temporal scales.

Explanation: Meiosis, along with fertilization that follows provides an abundance of phenotype possibilities that increases genetic diversity. In all cases of meiosis a parent cell divides into four gametes that each contain half the genetic material as the parent. In Meiosis 1 the homologous chromosomes exchange genetic material in a process called crossing over so the daughter cells each have a mix of the parents genes. When Meiosis 2 occurs these recombined chromosomes split into their respective sister chromatids creating a new genetically diverse gamete. Since crossing over happens at random segments of the DNA, the gametes formed are almost always different than the millions of others produced.

M.C. Question: In what way does the process of Meiosis contribute to genetic diversity?

A) It splits the sister chromatids unevenly, allowing for some gametes to have more genetic material than others

B) Homologous chromosomes exchange DNA in a process called crossing over in Meiosis 1

C) Gametes quickly exchange chromatids before they split apart in meiosis 2

D) Gametes form tight junctions between each other and exchange sections of chromosomes

Learning Log/ FRQ-style Question:

A)Explain how the Duplication, rearrangement, and reduction

of genetic material during meiosis contributes to genetic

Diversity within an organism.

B)Give an example of how an error in meiosis can lead to

Damaging traits in an organisim.


Explanation Meiosis and mitosis are two very similar processes, which both involve replication, duplication, and division of certain cells in the body. Meiosis differs from mitosis in the way that this process divides gamete cells, sperm cells in males, and egg cells in females. Mitosis is a process that occurs in all body cells, except for gamete cells which are used for sexual reproduction purposes. Meiosis is the main way that genes can be passed from genetic parents down to their offspring. When the two gametes of each sex come together, or fertilize, the genes are mixed and are expressed in different ways in their offspring. Many genes are expressed either dominantly or recessively in the offspring, but this depends on the parents genes that are passed on. An example would be if you have received a dominant trait for widows peak from both parents, then you will receive that trait. This principle can also apply to someone who receives a dominant and recessive geneforthis one trait from each of the parents, but if given both recessive genes then trait will not be expressed.

LO 3.11 The student is able to evaluate evidence provided by data sets to support the claim that heritable information is passed from one generation to another generation trough mitosis, meiosis, followed by fertilization

  • M.C. Question Based on what you know about mitosis and meiosis, which of the following is false concerning these two processes?
  • Meiosis is the process of dividing a nucleus of the cell into two cells who each have half the number of chromosomes as the 1st phase.
  • Mitosis is a way for the body to repair tissues and fibers.
  • Meiosis is a process where cells are split two separate times, with chances of chromosomal mixing.
  • Mitosis is an asexual, six step process that replicates cell information to make a cell of equal standards.

SP 5.3 The student can evaluate the evidence provided by data sets in relation to a particular scientific question.

FRQ-style Question: If you have chromosomal deficiencies in your cells, is that a problem with the meiosis or mitosis process? Why? In what ways could a negative altercation of mitosis become worse than a negative altercation of meiosis?


LO 3.12 The student is able to construct a representation that connects the process of meiosis to the passage of traits from parent to offspring.

  • SP 1.1 The student can create representations and models of natural or man-made
  • phenomena and systems in the domain.

Explanation: Meiosis is the process by which gametes, or sex cells are produced from diploid parent cells to create haploid cells in order to facilitate the fusion with a haploid of the opposite sex and produce genetically different offspring. During interphase, homologous pairs of chromosomes line up in the cell, these chromosomes represent DNA that was received from the parent organism. Crossing over can occur at the chiasmata of homologous nonsister chromosomes during prophase I. This crossing over allows for increased genetic variability as genes from different chromosomes are able to be exchanged. After crossing over the homologous chromosomes are pulled to opposite poles by microtubules attached at the centromere. After telophase I and cytokinesis, the two diploid cells then have the sister chromosomes, which contain the alleles that determine genetic and phenotypic traits of the offspring, separated and the cells undergo cytokinesis once more to create four haploid cells that are genetically different from the parent. These gametes have only half of the alleles for each parental trait, increasing the genetic possibilities for the offspring.

M.C. Question: Which of the following statements is true regarding meiosis?

A) Meiosis involves the duplication and separation of genetically identical cells.

B) Meiosis allows for increased genetic diversity by producing four gametes that have differing genetic material from the parent cell, thus enabling the offspring to differ from the two parent organisms.

C) Epidemics can move through a population with greater ease if the species’ reproductive system uses meiosis due to the resulting decrease in genetic variability.

D) Meiosis is a more efficient way to reproduce as it requires less steps and energy than simple mitosis.

Free Response Question:Suppose an organism has an unknown adaption due to the allele AaBb. Create a labeled diagram to trace the passage of the allele from the parent to its offspring. Why is the use of meiosis more beneficial to the species as a whole? What is one potential problem that the process of meiosis could cause for the offspring?


LO 3.13 The student is able to pose questions about ethical, social or medical issues surrounding human genetic disorders.

The student can pose scientific questions.

Explanation: There are many different genetic disorders that can affect the human body. Most of them can affect that person for the rest of their lives. One of the disorders is called Turner’s Syndrome it is a mutation in the genome that stops a protein from forming correctly thus not removing waste from the nerve cells.

MC Question

If a patient is suspected mentally handicapped. What would be the most likely method for Turner’s syndrome testing.

A) test for a gene for coding for an enzyme that breaks down waste in the brain.

B) A extraction of a sample cell to test for waste.

C) Use X Rays to look at the entire body

D) Remove the affected cells of the patient

In this picture the doctor is extracting the amniotic fluid from the womb, the doctor could then test the fluid for various genetic disorders. The parents then could decide weather to keep the baby or not. This raises many ethical issues


Describe the four different genetic disorders from the list and explain the consequences of having the disorder in molecular level as well as in life in general.

Tourette Syndrome , Colorblindness, Huntington's disease,  sickle-cell anemia.


LO 3.14: The student is able to apply mathematical routines to determine

Mendelian patterns of inheritance provided by data sets.

SP 2.2: The student can apply mathematical routines to quantities that describe natural


Explanation: You can use rules of probability to determine the chances of a certain coupling to reproduce an offspring with a certain genotype. For example, if you cross a male with the genotype AaBb with a heterozygous female with the same genotype and you want to figure out the probability of them producing an offspring with a genotype AABB, you would multiply ½ x ½ because there is a ½ chance of producing AA from AaxAA and a ½ chance of producing BB from BbxBB.

M.C. Question: If you do the cross AABBxAaBb, what are the chances of an offspring with the genotype AaBb being produced?

A) 1/2

B) 1/4

C) 1/64

D) 1/8

E) 1/16

FRQ: Describe the three types of genetic dominance and provide an

example of each, making sure to explain the effects on the

phenotype of an offspring.


LO 3.15 :The student is able to explain deviations from Mendel’s model of the inheritance of traits.

SP 6.5: The student can evaluate alternative scientific explanations.

Explanation: The inheritance pattern of many traits can be explained by simple Mendelian genetics. Many traits are products of multiple genes or various physiological processes that don’t occur naturally. Traits that don’t follow Mendel’s laws can be identified when resulting phenotypic ratios differ statistically from predicted ratios and results. Some traits are sex linked and determined by genes on the sex chromosome (X Chromosome in humans.) In mammals and flies, females are XX and males are XY, the Y Chromosome is small and carries few genes, therefore X-linked recessive traits are always expressed in males. Some traits are sex limited and expression depends on specific sex; examples being milk production in females and pattern baldness in males. Some traits result from nonnuclear inheritance such as with chloroplasts and mitochondria which are randomly assorted to gametes and daughter cells; thus, traits determined by chloroplasts and mitochondrial DNA don’t follow Mendelian rules. In animals, mitochondrial DNA is transmitted by the egg instead of the sperm therefore all mitochondrial-determined traits are inherited from the mother.

M.C. Question: Albinism is a lack of pigmentation in humans caused by

an autosomal recessive gene. What is the probability that two parents

with normal pigment have 3 children in a row that all suffer from






Learning Log/FRQ-Style Question:

State the conclusions reached by Mendel in his work on

the inheritance of characteristics. Explain how each of the

following deviates from these conclusions:

A. Autosomal linkage

B. Sex-linked (X-linked) inheritance

C. Polygenic (multiple-gene) inheritance


LO 3.16: The student is able to explain how the inheritance patterns of many traits cannot be accounted for by Mendelian genetics.SP 6.3: The student can articulate the reasons that scientific explanations and theories are refined or replacedExplanation: The patterns in which traits are inherited, cannot all be accounted for by Mendelian genetics. Mendel has set laws, but not all traits fall onto the path these lead. Some observed phenotypic ratios can statistically differ from the predicted outcomes. Along with this, some genes can be passed down on sex chromosomes. An example of a sex-chromosome-linked trait would be colorblindness. This is a recessive allele found on the x-chromosome, affecting males more frequently. Mendelian genetics do not account for sex linked traits, therefor ot accounting for the colorblind allele. Another example of sex linked traits, would be milk production and pattern baldness. Mendel stated that different traits are inherited independently of each other, so there is no relation, but this is only true for traits that are not linked to each other. In some cases, with the use of Mendel’s laws, incomplete dominance would occur. Incomplete dominance is when the dominant allele does not seem as apparent. For example, a red flower and a white flower are crossed, and a pink flower is the product, the pink flower is a mixture showing incomplete dominance. Another circumstance like incomplete dominance is co-dominance. In this scenario, a red flower and white flower would come out with a flower that is speckled both red and white. Now, Mendel’s laws of genetics have been modified into what we call “modern genetics” where most of his ideas are still relevant. Multiple Choice: Colorblindness is sex-linked and recessive in humans. A woman with normal vision but whose father was color blind marries a man with normal vision whose father was also color blind. What type of allele can be expected of their four offspring?A) both sons being colorblind, both daughters carriersB) one daughter and one son colorblind, and one daughter and one son carriersC) one son normal, one daughter normal, one son colorblind, and one daughter a carrierD) one son colorblind, one son carrier, and both daughter carriersFree Response Question:Draw and label a pedigree showing the passage of the sex-linked allele of colorblindness. Make sure to describe all factors contributing to the outcomeand why it happened.


LO 3.17: The student is able to describe representations of an appropriate example of inheritance patterns that cannot be explained by Mendel’s model of the inheritance of traits.

SP 1.2: The student can describe representations and models of natural or man-made phenomena and systems in the domain.

Explanation: Mendel’s model of inheritance is based on the idea that each parent contributes one of two possible alleles for a trait. If the genotype of the two parents is known, the distribution of phenotypes expected for the population of offspring can be determined. The unusual inheritance patterns are incomplete dominance, codominance, multiple alleles, epistasis, pleiotropic, polygenic, and linked genes. Incomplete dominance is the idea that two phenotypes are blended rather than showing two different possibilities. Before Mendel, it was believed that organisms underwent incomplete dominance and therefore the blended parental traits could not be separated in later generations. Codominance is when both alleles are expressed at the same time. Multiple alleles is when there are more than two alleles. Blood type is controlled by three alleles: A, B and O. AB blood type is an example of codominance.Epistasis is when a gene at one location affects or alters the expression of a gene at another location. Pleiotropy is the ability of a single gene to exert influence on several characteristics, meaning that they have multiple effects on the phenotype of the species (many arise from genes whose products are involved in signaling and regulation pathways). Polygenic inheritance is when a phenotype is determined by two or more genes. Linked genes are genes that stay together during assortment and move as a group. Sex linked traits (X-linked) are carried on sex chromosomes, and if the allele is defective on the X chromosome it will show up on males much more than females because women have Barr bodies.

M.C. Question:

Which of the following statements concerning sex-linked traits is true?

A female offspring's expression of a sex-linked trait is determined by the genotype of her mother.

A female offspring's expression of a sex-linked trait is determined by the genotype of her father.

Male and female offspring have the same probability for the expression of a sex-linked trait.

d. A male offspring’s expression of a sex-linked trait is determined by the father.

B and D

Learning Log/FRQ-style question:

Look at the picture below and explain the phenotypic ratio of the first and second generations of offspring. Explain the inheritance principle that allows pink flowers to be made. Use punnett squares in your explanation.






Transcription unit

Start point

RNA polymerase

Initiation. After RNA polymerase binds to

the promoter, the DNA strands unwind, and

the polymerase initiates RNA synthesis at the

start point on the template strand.

Template strand of DNA





Elongation. The polymerase moves downstream, unwinding the

DNA and elongating the RNA transcript 5 3 . In the wake of

transcription, the DNA strands re-form a double helix.





Termination. Eventually, the RNA

transcript is released, and the

polymerase detaches from the DNA.

LO 3.18: The student is able to describe the connection between the regulation of gene expression and observed differences between different kinds of organisms.SP 7.1: The student can connect phenomena and models across spatial and temporal scales.

Explanation: Gene regulation accounts for some of the phenotypic differences between organisms with similar genes. Gene expression is controlled by an inducer and inhibited by a repressor. Regulatory proteins inhibit gene expression by binding to DNA and blocking transcription. They stimulate gene expression by binding to DNA and stimulating transcription or binding to repressors to inactivate repressor functions. The combination of transcription factors binding to regulatory regions determine how much of the gene product will be produced.

Stages of Transcription:

M.C. Question: In prokaryotes, gene expression involves:

A) regulatory genes

B) transcription factors

C) Regulatory elements











Learning Log/FRQ-style Question: Organisms share a high quantity of DNA. Give phenotypic evidence of different organisms sharing similar DNA.













Completed RNA transcript


LO 3.19: The student is able to describe the connection between the regulation of gene expression and observed differences between individuals in a population.

SP 7.1: The student can connect phenomena and models across spatial and temporal scales.

Explanation: The regulation of genes in a population effects the expression of genes and the overall appearance of the population. The differences in the expression of certain genes changes physical appearances caused by either the activation or repression of the gene. Regulatory genes can be influenced by environmental factors that could, for example, effect wing shape in fruit flies. The repressors are activated to stop processes like the growth of harmful cells to keep the body healthy. Regulatory genes work by binding or unbinding to a gene to stimulate or repress the transcription of it.

MC Question: What would not be an instance when gene regulation would be used?

Stopping the growth of a tumor

Genetic changes in the body color of a fruit fly

The shift in a population toward larger animals

The building of certain proteins used in RNA

FRQ Question:

Regulatory genes regulate protein activity.

Discuss TWO specific mechanisms of

protein regulation in eukaryotic cells.


LO 3.20 The student is able to explain how the regulation of gene expression is essential for the process and structures that support efficient cell function. [see SP 6.2] SP 6.2 The student can construct explanations of phenomena based on evidence produced through scientific practices.Explanation: Gene expression is necessary for cells to function properly; it allows cells to differentiate into different organs. The same genes can be expressed in an array of ways from the same DNA.Multiple Choice: Why may a set of identical twins each have a feature that slightly appears to differ from his/her sibling?A )They aren’t really identical.B) There has been a mutation of genes in one of the twins.C) The code for that particular gene may be expressed in a variety of ways depending on how the body translates/reads it.D) There has been a deletion of insertion.E) Both a and d are correct.FRQ:Gene expression regulates efficient cell function in many ways. Explain how the following contributes to this:a) cell differentiationb) role of proteinsc) DNA methylation


LO 3.21 The student can use representations to describe how gene regulation influences cell products and function.SP 1.4 Gene regulation accounts for some of the phenotypic differences between organisms with similar genes.Explanation: Regulation of gene expression refers to the control of the amount and timing of appearance of the functional product of a gene. Control of expression is vital to allow a cell to produce the gene products it needs when it needs them; in turn this gives cells the flexibility to adapt to a variable environment, external signals, damage to the cell, etc. Some simple examples of where gene expression is important are: control of Insulin expression so it gives a signal for blood glucose regulation X chromosome inactivation in female mammals to prevent an "overdose" of the genes it contains. Cyclin expression levels control progression through the eukaryotic cell cycle, more generally gene regulation gives the cell control over all structure and function, and is the basis for cellular differentiation, morphogenesis and the versatility and adaptability of any organism. Any step of gene expression may be modulated, from the DNA- RNA transcription step to post-translational modification of a protein. The stability of the final gene product, whether it is RNA or protein, also contributes to the expression level of the gene - an unstable product results in a low expression level. In general gene expression is regulated through changes in the number and type of interactions between molecules that collectively influence transcription of DNA and translation of RNA.

Which of the following statements correctly describes promoters in E. coli?

A) A promoter may be present on either side of a gene or in the middle of it. B)Every promoter has a different sequence, with little or no resemblance to other promoters. C) Many promoters are similar and resemble a consensus sequence, which has the highest affinity

for RNA polymerase holoenzyme. D) Promoters are not essential for gene transcription, but can increase its rate by two- to three-fold.

Describe and contrast positive regulation and negative regulation of gene expression.


LO 3.22: The student is able to explain how signal pathways mediate gene expression, including how this process can affect protein production.

SP 6.2: The student can construct explanations of phenomena based on evidence produced through scientific practices.

Explanation: Signals can be transmitted between cells through paracrine, local signaling, or endocrine, long distance signaling, pathways using signal molecules called ligands. These ligands bind to receptor proteins either on the surface of the plasma membrane, or inside the cell. Steroid hormones are lipids, so they are hydrophobic and can travel through the plasma membrane, so they attach to receptors inside the cell, creating a hormone-receptor complex, which travels to the nucleus and activates certain genes to be transcripted into RNA and then translated into specific proteins. Protein ligands are hydrophilic and cannot pass through the plasma membrane, so they bind to receptors in the extra-cellular-matrix and can allow certain genes to be transcripted and/or cause other responses within the cell. When a ligand binds to a Tyrosine-Kinase receptor, the two separate halves form a dimer, which phosphorylates using ATP and initiates relay proteins. Once a ligand binds to a G-Protein-Linked receptor, the receptor phosphorylates a G-protein using GTP. The G-protein then phosphorylates an enzyme. Ligand gated ion channels either open when the

ligand attaches to let ions pass freely between the cytosol and extracellular fluid

or close when the ligand attaches to cease the flow of ions.

  • M.C. Question: Explain why a steroid hormone binds to receptors inside the cell when protein ligands bind to receptors in the extra-cellular matrix.
  • Steroid hormones mediate gene expression, so they have to bind to their receptors while they are in the nucleus.
  • Protein ligands only bind to ligand-gated-ion channels, which must be embedded in the plasma membrane.
  • Steroid hormones can travel through protein channels across the plasma membrane to enter the cell and protein ligands cannot.
  • Steroid hormones are hydrophobic, so can travel through the plasma membrane and protein ligands are hydrophilic, so they cannot.
  • Learning Log/FRQ-style Question: Explain how a signal can be transmitted from one cell to another cell resulting in a physical response by the cell and the alteration of gene expression in the receptor cell. Include in your explanation two types of receptor proteins and describe how they function.

LO 3.23: The student can use representations to describe mechanisms of the regulation of gene expressionSP 1.4: The student can use representations and models to analyze situations or solve problemsqualitatively and quantitatively

Explanation: In cells, gene regulation is necessary to regulate the production of gene products. In DNA, demethylation occurs to prevent transcription from occurring. Acetylation unwinds DNA for simple transcription to take place. In RNA, small interfering RNA or siRNA, targets and degrades mRNA.  In DNA, the promoter reigon increases RNA polymerase binding while the Enhancer increases transcription. DNA packaging tightens or loosens the chromatin to inhibit or promote transcription.

M.C. Question: Which of the following is not involved in gene regulation?

a) RNA processing

b) Apoptosis

c) Degredation of mRNA

d) Cleavage and Transport

FRQ: Cancer is caused by mutations and errors in regulation. Describe the factors necessary for cancerous cells to develop.


LO 3.24: The student is able to predict how a change in genotype, when expressed as a phenotype,

provides a variation that can be subject to natural selection.

SP 7.2: The student can connect concepts in and across domain(s) to generalize or extrapolate

in and/or across enduring understandings and/or big ideas.

Explanation: Mutations, random changes in DNA sequences, are the most common cause of genetic variation. When DNA sequences (genotypes) are altered, the phenotype of an organism may be altered as well due to changes in protein production, and depending on the environment and natural selection, such altered phenotypes may be beneficial to organisms (as genetic variation often is). In a population of bacteria, for example, a few individual bacteria may develop (by mutation) antibiotic-resistance genes. If this happens, then the mutated bacteria will survive and produce offspring that is completely resistant to the antibiotic. In this way, small changes in the genotypes of just a few individuals can lead to the evolution of an entire population.

M.C. Question: Which of the following is true?

A) Nondisjunction of chromosomes is always fatal to an organism.

B) A chromosomal point mutation generally causes more drastic changes in genotype than a chromosomal deletion.

C) Females with trisomy X are phenotypically indistinguishable from normal XX females.

D) Evolutionary forces always select against mutated organisms.

Learning Log/FRQ-style Question: The antibiotic-resistance gene developed by the bacteria described above is one example of a beneficial mutation. Provide another. Also, describe some of the mechanisms by which mutations are prevented during or after DNA replication.


LO 3.25: The student can create a visual representation to illustrate how changes in a DNA nucleotide sequence can result in a change in the polypeptide produced.

SP1.1: The student can create representations and models of natural or man-made phenomena and systems in the domain.

Explanation: Nucleotides are known as the basic building block for the construction of polypeptide chains, most commonly known as proteins. They consist of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group. There are four nitrogenous bases included in DNA: adenine, thymine, cytosine, and guanine. In RNA the thymine is replaced with uracil. Nucleotides are read in intervals of three and represent a codon. If a single nucleic acid is changed, then the specified codon would also be different. Codons, in turn, are translated into amino acids that form peptide chains. The most common type of mutation is a point mutation. In point mutations, a single base-pair is changed. There are 3 kinds of single base-pair mutations: base-pair substitutions, insertions, and deletions. A base-pair substitution is the replacement of one nucleotide and its partner with another pair of nucleotides. It may lead to silent, missense, or nonsense mutations. If no change is made to the amino acid sequence, then the mutation is silent. Most substitution mutations are missense mutations; the altered codon still codes for an amino acid and thus makes sense, although not necessarily the right sense. If a change in the nucleotide results in the premature ending of the polypeptide chain, it is known as a nonsense mutation. Insertions and deletions are additions or losses of nucleotide pairs in a gene. Such a change can cause the reading frame, codons, to change. Such a mutation, called a frameshift mutation, will occur whenever the number of nucleotides inserted or deleted is not a multiple of three. The following codons will then be incorrect. In turn, the entire polypeptide chain after that point will also be incorrect.

M.C. Question: Which of the following changes to the DNA sequence, AGC-GCT-TAA-CGC-AGT-ATT-CGA-GCT, would have the greatest effect when being translated into amino acids?

a. The guanine in the first triplet is replaced with a thymine nitrogenous base.

b. The guanine in the fourth triplet is replaced with a cytosine nitrogenous base.

c. The guanine of the eighth triplet is replaced with a adenine nitrogenous base.

d. The guanine of the seventh triplet is replaced with a thymine nitrogenous base.

Learning Log/FRQ-style Question: Information flow can be altered by mutation. Describe three different types of mutations and their effect on protein synthesis.


LO 3.26: The student is able to explain the connection between genetic variations in organisms and phenotypic variations in populations.

SP 7.2: The student can connect concepts in and across domain(s) to generalize or extrapolate in and/or across enduring understandings and/or big ideas.

Explanation: Random changes in a DNA sequence, or mutations, create genetic variations that in turn alter the consequent phenotypes in a positive, negative, or neutral manner depending on external environmental factors. Such a change can be caused by errors in DNA replication or repair mechanisms. For example, a deletion of a segment of DNA causes the entire strand to be transcribed differently, as is the same with an insertion of a segment in the middle of a strand. Mistakes in meiosis or mitosis, where a cell divides, can also result in DNA variation and thus, change the individual’s phenotype. In a nondisjunction, the members of a pair of homologous chromosomes don’t move apart properly during meiosis I or sister chromatids fail to separate during meiosis II. Because of this, one gamete will receive two of the same chromosome while the other gamete receives none. An example of this aneuploidy condition is down syndrome, where there is an extra chromosome in chromosome 21. This mutation causes both developmental and physical phenotypes that would not occur normally. Changes in genetic variation that cause a detrimental phenotype in the individual will have a negative effect. Only genetic changes that enhance survival will be carried to the offspring to remain circulating within the population.

M.C. Question: Multiple crosses involving genes known to occur on the same chromosome produce frequencies of phenotypes that suggest there is a high rate of crossover between these two genes. Which of the following is the most likely explanation for the phenotypic frequencies observed due to crossing over?

(A) The two genes are far apart from one another.

(B) The two genes are both recessive.

(C) The two genes have incomplete dominance.

(D) The two genes are both located far from the


Learning Log/FRQ-style Question: A change in an individual’s

DNA may result in a phenotype that is affected by natural

selection. Describe and explain a situation in which a change

in an organism’s DNA may be beneficial for that organism’s

survival and one in which the mutation would be detrimental.


LO 3.27: The student is able to compare and contrast processes by which genetic variation is produced and maintained in organisms from multiple domains.

SP 7.2: The student can connect concepts in and across domain(s) to generalize or extrapolate in and/or across enduring understandings and/or big ideas.

Explanation: Genetic variation within a population is a shared characteristic among organisms that ensures efficient evolutionary changes. The DNA within a eukaryote must be proofread and the reparation technique of DNA polymerase further increases the chance of variation among genes. Among an organism’s chromosomes, independent assortment occurs in Metaphase I of Meiosis, producing a random pairing of chromosomes. The crossing over of chromosomes in Prophase I ensures genetic variation by creating new chromosome combinations, leading to random fertilization. In contrast, transformation in prokaryotes leads to recombinant DNA as external DNA is assimilated into the plasmid, changing the cell’s genotype and phenotype. Transduction along with conjugation lead to genetic recombination as genetic material is transferred from one cell to the other. Transposition also creates variations as sections of DNA are moved to different places due to exon shuffling. Reproduction processes that increase genetic variation are essential for organisms to maintain a population and ensures the success of that population through natural selection.

M.C. Question: What is the role of exon shuffling in providing genetic diversity to a population?

It allows transposons on a section of RNA to copy and paste itself elsewhere, thus creating different proteins.

It causes bacteria to have a recombinant plasmid.

It causes new genes to evolve as sections of DNA are moved to different places.

It randomly assorts chromosomes along the Metaphase plate during Metaphase I of Meiosis.

Learning Log/FRQ-style Question: Suppose you were an expert in DNA technology and were given the task to insert a gene of interest into the plasmid of a bacterial cell and clone it. Describe how the transformation process works. Describe three additional ways in which bacterial cells become genetically recombinant.


LO 3.28:The Student is able to construct an explanation of the multiple processes that increase variation within a population.SP 6.2: The student can construct explanations of phenomena based on evidence producedthrough scientific practices

Explanation: Mutations that naturally occur in DNA replication can change or alter the DNA for future organisms. The movement of DNA that can take place in Transformation(the taking of raw DNA), Transduction(the taking in of Viral DNA), Transposition(the movement within it's own sequence of DNA), or Conjugation(the movement between cells). Sexual reproduction involving random fertilization, crossing over during the Metaphase of Meiosis, and the random assortment of the chromosomes during the Metaphase, where the line up across the middle in any order.

MCQ: Which of the following is NOT a way that organisms are assisted in genetic diversity?

A. A disease that was contracted as a child

B. The contraction of a virus

C. Reproduction with a 12th cousin, twice removed

D. Changes in the DNA that occur before birth.

FRQ: Harry contracted a virus as a child which altered DNA,

please explain in detail how this virus altered DNA and

explain how, if so, this would increase diversity if he mated.


LO 3.29: The student is able to construct an explanation of how viruses introduce

genetic variation in host organisms.6.2 The student can construct explanations of phenomena based on evidence produced through scientific practiceExplanation: Viruses can introduce genetic variation into bacterial cells via transduction. There are two different types of transduction: generalized, and specialized. Generalized is done when a phage infects a cell and makes copies of itself using part of that cells DNA, this is the “donor” cell. Then phages produced from this cell carry DNA and infect other cells, bringing along the DNA and transferring it into those cells to make the recombinant cell. In specialized the prophage collects some genetic material as it exits the chromosome and takes it to a new cell. This is more efficient, but only works for genes adjacent to the prophage site.

M.C. Question: Which one of these statements is false about Transduction?A) Transduction can only occur in bacterial cells.B) Only one cell needs to be infected in order for genetic variation to happen.C) Specialized transduction happens during the lysogenic cycle.D) Transduction is not a 100% way to get a certain gene transferred.Learning Log/FRQ-style Question: While many see viruses as bad, theythrough transduction can be used to quickly spread genetic material fromone organism to another. Suppose you are researching which bacteria areresistant to a virus, using your knowledge of transduction, design anexperiment to find out.


LO 3.30: The student is able to use representations and appropriate models to describe how viral replication introduces genetic variation in the viral population.







Entry of phage DNA and degradation of host DNA.


Phage assembly

Synthesis of viral genomes and proteins.


Tail fibers



SP 1.4: The student can use representations and models to analyze situations or solve problems

qualitatively and quantitatively.

Explanation: Genetic variation can be introduced in a viral population through mutations during viral replication. For example, phage viruses replicate via a component assembly model allowing one virus to produce many progeny via the lytic cycle. Here phages attach to a host cell and phage DNA is injected. The cell’s DNA is hydrolyzed, and phage DNA commandeers production of phage proteins and copies of the phage genome using host enzymes and components already within the cell. Sets of proteins assemble to compose phage heads, tails, and tail fibers. The newly completed phages are released when the phage produces an enzyme to damage the host cell wall, allowing fluid to enter and causing the cell to burst. Between 100 and 200 phage particles are released with each lysis. As potential bacterial hosts evolve to possess receptor sites unattractive to phages or develop restriction enzymes that cut up foreign viral DNA, mutations among phages to resist certain enzymes are favored by natural selection and persist in succeeding generations. Genetic variation can also occur by way of mutations in RNA viruses that lack error-checking mechanisms and by combination/recombination of genetic material when related viruses attack the same host cell.

  • M.C. Question: Lysogenic bacteriophages have the capacity to transfer a piece of cell DNA adjacent to the prophage to another cell. This is known as specialized:
  • A) Invagination
  • B) Endocytosis
  • C) Transduction
  • D) Transformation

Learning Log/FRQ-style Question: Consider the case of an RNA virus: Is genetic variation any more or less likely to occur than in a similar DNA virus? Explain. Draw and label a model of the RNA viral reproductive cycle and indicate where genetic variation is likely to occur.


LO 3.31: The student is able to describe basic chemical processes for cell communication shared across evolutionary lines of descent.

SP 7.2: The student can connect concepts in and across domain(s) to generalize or extrapolate

in and/or across enduring understandings and/or big ideas.

Explanation: Cells must be able to communicate with other cells in order to respond to their external environment and successfully thrive in a biological system. The basic chemical processes by which cells communicate are shared across evolutionary lines of descent, and communication schemes are the products of evolution because correct and appropriate signal transduction processes are generally under strong selective pressure. Cell communication can range anywhere from organ differentiation to whole organism physiological responses and behaviors, and these end results are usually achieved through cell-to-cell contact, plasmodesmata, or receptor-to-recognition protein interaction. Chemical signaling pathways in cells are determined by the properties of the molecules involved, the concentrations of signal and receptor molecules, and the binding affinities (fit) between signal and receptor. The signal can be a molecule or a physical or environmental factor, ultimately resulting in a change in gene expression, protein activity, or physiological state of the cell or organism, including cell death (apoptosis).

M.C. Question: Which of the following statements concerning cell communication is/are true?

A)The use of pheromones can trigger reproduction and developmental

pathways through cell communication.

B)Apoptosis, programmed cell death, is achieved through a signal cascade that

alters active genes.

C)A signal cascade is initiated when a ligand binds to DNA.

D)Both A and B

Learning Log/FRQ-style Question: Why is it important for cell-to-cell

communication to function quickly and effectively? Why do you think cell

communication in many species functions in very similar ways, and what do

you think would happen to an organism that has dysfunctional signal cascade



LO 3.34: The student is able to construct explanations of cell communication through cell-to-cell direct contact or through chemical signaling.

SP.2:The student can construct explanations of phenomena based on evidence produced through scientific practices.

Explanation: Cells are responsible for communicating with other cells through cell-to-cell direct contact, or by chemical signaling. Communication occurs in various ways in animal cells, including interaction between immune cells and antigen-presenting cells, helper t-cells and killer t-cells. These living cells interact through endocrine and paracrine signaling, by using local regulators that target cells, such as Neurotransmitters. These neurotransmitters are responsible for carrying information from a neuron released by the nerve terminal to another neuron, by crossing a gap called a synapse that allows the next neuron to receive information at it’s receptor. In plants, the plasmodesmata is responsible for communicating information between plant cells that allow material to be transported from cell to cell. The plasmodesmata creates a channel in the cell wall of the plant cell that allows for information to be passed along to the “attached” cell. With endocrine signaling, insulin and glucagon work together in keeping blood glucose levels in line. The pancreas releases glucagon into the bloodstream when blood glucose levels are too low. On the other hand, high levels of blood glucose causes the body to stimulate insulin into the bloodstream to lower the levels.

M.C. Question: Which of the following is not

an example of endocrine signaling?

A: Parathyroid Glands and Calcium

B: Thyroid glands and iodine

C: Glucagon and Insulin

D: Growth Factors and Clotting factors

E: None of the above

FRQ Style Question: Blood glucose levels decrease in the bloodstream. Explain the process the body goes through in order to increase the level back to normal. If the blood glucose levels would have increased, what would be the difference?


Local signaling

Long-distance signaling




(a) paracrine signaling


(b) Synaptic signaling.

(c) Hormonal signaling.





LO 3.35: The student is able to create representation(s) that depict how cell-to-cell communication occurs by direct contact or from a distance through chemical signaling.

SP 1.1: The student can create representations and models of natural or man-made phenomena and systems in the domain

  • M.C. Question: What is the correct order in which a helper T communicates with a killer T cell?
  • 1. Killer T cells secrete perforin proteins.
  • 2. Killer T cells are activated
  • 3. Killer T cells initiate clone killer T cells
  • 4. Helper T cells activate & secrete cytokines
  • 5.Helper T cell binds to a molecule on a dendritic cell
  • 6. Helper T cells initiate clone helper T cells
  • A. 4,5,6,1,2,3 B 2,1,3,4,6,5
  • C. 5,4,6,2,3,1 D 5,6,4,2,3,1
  • E. 6,5,4,2,1,

Learning Log/ FRQ: Name 3 different glands of the endocrine system. Identify its signaling pathway . Name a hormone of each gland and what various responses it causes and what it affects

Explanation: Two types of cell to cell communications are illustrated in paracrine (local) and endocrine (long distance) signaling. The 3 stages in signaling are reception (the ligand or signal molecule binding to a receptor), transduction (converting the signal to a cell response by relay molecules) and a cell response. Direct cell communications can be illustrated by gap junctions in animals & plasmodesmata in plant cells, and cell-to-cell recognition. These cell junctions allow for molecules to pass through adjacent cells without crossing the plasma membranes. In cell-to-cell recognition, two cells may communicate by membrane-bound surface molecules. An example of cell-to-cell recognition is immune cells interacting by antigen-present cells (APCs) helper-T cells and killer-T cells. Local signaling use local regulators secreted by a cell to stimulate a target cell's response. Examples of local signaling are paracrine signaling: A secreting cell releases local regulators into into the extracellular fluid near target cells; and synaptic signaling” never cell releases neurotransmitters into synapses stimulating the target cell or neuron. Distant cell signaling can be illustrated by hormones and the endocrine system. An endocrine gland releases hormones in 3 different pathways: simple endocrine, simple neurohormone, and simple neuroendocrine. An illustration of simple endocrine is the pancreas releasing insulin as a result of low blood glucose. An example of simple neurohormone is suckling stimulating the hypothalamus and posterior pituitary to release Oxycontin An example of neuroendocrine is the hypothalamus releases a neural and hormonal response to the anterior pituitary to release another hormone to target cells.


LO 3.36: The student is able to describe a model that expresses the key elements of signal transduction pathways by which a signal is converted to a cellular response.

SP 1.5: The student can reexpress key elements of natural phenomena across multiple

representations in the domain.

Explanation: In cell communication, signal molecules such as hormones are received by cells to carry out a cellular response. The 3 stages of cell signaling are reception, transduction, and response. In reception, the ligand binds to a receptor; these receptors include intracellular receptors, G-protein-linked receptors, tyrosine kinase receptors, and ligand-gated ion channels , each creating a unique cell response. In transduction, the signal from reception is converted to a specific cellular response often by protein phosphorylations and then 2nd messengers that deliver the final cell response which may include enzyme activation or gene transcription.

M.C. Question: Which of the following statements concerning signal receptors is true?

An intracellular receptor may receive polar hormones.

ATP displaces ADP to activate the G-protein after reception.

Tyrosine kinase receptors form a phosphorylated dimer to activate relay proteins.

Ligand-gated ion channels allow ions to flow against the concentration gradient.

Learning Log/FRQ-style Question: Describe in detail the process by which epinephrine triggers a cell response. Be sure to include reception, transduction, and cell response.


LO 3.38 The student is able to describe a model that expresses key elements to show how change in signal transduction can alter cellular response.SP 1.5 The student can reexpress key elements of natural phenomena across multiplerepresentations in the domain.

  • Explanation:
  • Signal transduction is defined as the ability of a cell to change behavior in response to a receptor-ligand interaction. The ligand is the primary messenger. As the result of binding the receptor, other molecules or second messengers are produced within the target cell. Second messengers relay the signal from one location to another (such as from plasma membrane to nucleus). Often a cascade of changes occur within the cell which results in a change in the cell’s function or identity. The signal transduction pathway can act to amplify the cellular response to an external signal. Messenger molecules may be amino acids, peptides, proteins, fatty acids, lipids, nucleosides or nucleotides. Hydrophilic messengers bind to cell membrane receptors. Hydrophobic messengers bind to intracellular receptors which regulate expression of specific genes. So, changes in signal transduction will completely alter the cellular response.
  • Multiple choice:
  • In signal transduction, if the receptor is altered, which of the following will happen? a) the cellular response will go on as normal b) there will be a different cellular response c) the cell will stop all functions d) the cell will burst.
  • FRQ:
  • A) Describe the basic principles of signal transduction.
  • B) Think of 3 examples of signal transduction receptors.
  • C) Compare and contrast 2 of the examples of signal transduction receptors.

LO 3.39: The Student is able to construct an explanation of how certain drugs affect signal reception and, consequently, signal transduction pathways.SP 6.2: The student can construct explanations of phenomena based on evidence produced through scientific practices.

Explanation: Certain drugs such as opiates mimic the shapes of ligands, which bind to the specific ligand receptors. This mimicry prevents the naturally produced neurotransmitters from binding to the receptor site. As more and more of the opiate is absorbed the body stops making the natural chemical which leads to addiction and withdrawal when the artificial chemical is no longer absorbed.

M.C. Question: Suppose a healthy individual who has never used a morphine based drug decided to inject themselves with heroin. How would the body react to the initial injection?

A.) The individual would receive the instant gratification of a high with few residual symptoms.

B.) The individual would experience nausea and vomiting due to the sudden chemical imbalance in the nervous system.

C.) The individual would experience cross tolerance and would feel little to no effect from the drug.

D.) The morphine ligand would not be able to bind to the receptor site and would have no effect on the individual.

E.) The drug would immediately show inhibitory effects causing the individual to feel sluggish and uncaring.

Learning Log/FRQ Question: In the body natural endorphin acts as a natural stimulant and pain reliever. Endorphins can inhibit neurons from firing and create a natural analgesic affect or excite the neurons which gives the organism a feeling of euphoria. In a recently recovering heroin addict, how would the body be affected if the person went through a vigorous workout?


Moist site under leaf

Dry open area

(a) Kinesis increases the chance that a sow bug will encounter and stay in a moist environment.

Direction of


(b) Positive rheotaxis keeps trout facing into the current, the direction from which most food comes.

  • LO 3.40- The student is able to create a representation that describes how organisms exchange information in response to internal changes and external cues, and which can result in changes in behavior.
  • SP 1.1- The student can analyze data to identify patterns or relationships.
  • Explanation: Behavior is everything an animal does and how it does it. It is separated into two categories for causes: proximate(nature) and ultimate(nurture). Breeding times, physiological adaptations to environments and more are all proximate observations. Specific behaviors such as fixed action patterns (red stimuli induces attacks in male stickleback fish), imprinting (young geese during a critical period follow initial stimuli of an organism moving away),and communication (round and waggle dances in honeybees) are characterized as innate, or strongly-genetically induced. Learned behaviors are responses to environmental stimuli, as is seen in operant , where responses are voluntary, and classical conditioning, where responses are involuntary. Consider Pavlov’s bell experiment and the navigation of mice through a maze, respectively. The dog salivated subconsciously after associating the bell ring with food and the mice after multiple trials-and-errors, learned to consciously locate the food at the end of a maze.

Which of the following is a behavioral pattern resulting from an ultimate cause?A) A male robin attacks a red tennis ball because it resembles the breast of another male.B) A male robin attacks a red tennis ball because hormonal changes in spring increase its aggression.C) A male robin attacks a red tennis ball because a part of its brain is stimulated by red objects.D) A male robin attacks a red tennis ball because several times in the past red tennis balls have been thrown at it, and it has learned that they are dangerous.E) A male robin attacks a red tennis ball because it confuses it with an encroaching male who will steal his territory.


Without adaptive behaviors, animals would not survive.

(a) Describe what innate and learned behaviors are. Explain the adaptive value of each of these two categories of behavior to an individual animal.

(b) During mating season, male snakes exhibit tracking behavior when they follow chemical pheromone trails deposited on the ground by females. Design a controlled experiment to determine whether a male garter snake will track only a female of his species or will also follow the female of a related species.


SP 1.1 The student can create representations and models of natural or man-made phenomena and systems in the domain.

LO 3.41 The student is able to create a representation that describes how organisms exchange information in response to internal changes and external cues, and which can result in changes in behavior.

MC: How is the distance to a food source communicated

by a dancing honeybee?

A)by the direction it waggles its abdomen

B)by how far it moves during the straight run portion

of the dance

C)by which direction it turns after making the straight run

D)by the tempo or degree of vigor of the dance

E)none of the above - bees can't communicate the distance

Explanation: Responses are dependent upon or influenced by underlying genetic information, and decoding in many cases is complex and affected by external conditions. For example, biological rhythms, mating behaviors, flowering, animal communications and social structures are dependent on and elicited by external signals and may encompass a range of responses and behaviors. Organ systems have evolved that sense and process external information to facilitate and enhance survival, growth and reproduction in multicellular organisms. These include sensory systems that monitor and detect physical and chemical signals from the environment and other individuals in the population and that influence an animal’s well-being. Individual behavior influences population behavior, and both are the products of information recognition, processing and transmission. Communication among individuals within a population may increase the long-term success of the population. Responses to information and communication of information are vital to natural selection and evolution.

Animals use many forms of communication to indicate dominance, find food, establish territory and ensure reproductive success. Describe how an animal can use audible, and chemical signals to transfer information. Include two examples in your answer.


LO 3.42: The student is able to describe how organisms exchange information in response to internal changes or environmental cues.

SP 7.1: The student can connect phenomena and models across spatial and temporal scales.

Explanation: Organisms exchange information by the traveling of neurons across the synapses. A neuron has a cell body, axons and dendrites. Axons are long threadlike parts of the nerve cell where impulses are carried. Many axons have a cover over them called a myelin sheath that acts as an electrical insulator. The myelin sheaths are made of cells called Schwann Cells. There are gaps in the myelin sheath called the Nodes of Ranvier. This is where the signal bounces from node to node. When Na+ ions come into the cell, the cell becomes less negative. When the cell becomes less negative it is called depolarized. The action potential is when more Na+ ions enter the cell and the nerve impulse is started. When K+ ions leave the cell, the cell becomes more negative. When the cell becomes less negative it is called hyperpolarization. The normal charge of a neuron is -70 mV; when the action potential is met and the threshold is achieved, the charge is -55 mV. After the threshold has been reached and the nerve impulse has finished, the sodium potassium pumps open and restore the system back to -70 mV by active transport.

M.C. Question: After the action potential of a neuron, which of the following restores the cell to -70 mV?

a) decrease in Na+ concentration

b) increase in K+ concentration

c) Aquaporins

d) Sodium potassium pumps

e) None of the above

Learning Log/ FRQ-style Question: Suppose you place a neuron in an aqueous solution containing free Na+ and K+ ions. Thresholds are reached and action potentials are created. Why does the action potential only travel in one direction? After the cell is restored to normal charge, how does a single neuron interpret multiple inputs?


AP Biology Exam Review: Learning Objective Focus

(A) LO 3.43: The student is able to construct an explanation, based on scientific theories and models, about how nervous systems detect external and internal signals, transmit and integrate information and produce responses.

(B) SP 6.2:  Student can construct explanations of phenomena based on evidenced produced through scientific practices

(C)Explanation: When an external or internal signal is received, sensory cells convert stimuli into action potentials. Nerve impulses/action potentials are received through the Dendrite of a pre-synaptic region of a neuron and transmitted to other cells through the axon of the neuron. At the end of the axon is called the axon terminals, this is where neuron may make contact with the dendrites of another neuron, with a receptor/effector. Receptors are sensory neurons in that receive stimuli from the external environment.The points of contact at which impulses are passed from one cell to another are known as the synaptic cleft, neurotransmitters are found inside. Neurotransmitters, chemical substances that are used to by one neuron to signal another. Nerve impulses are electrical as they move along the nerve and chemical as they travel over the synaptic cleft. After sensory neurons carry impulses they eventually reach the brain. The brain acts to interpret, sort, and process the incoming impulses and then produce on a response.

(D)Multiple choice:

•A women gets in a car accident and suffers from nerve damage in her right arm. After analyzing the injuries, the doctor concluded that a dendrite in her nerve cells  has been severed. What will  most likely be the  effect of this damage?

•A. There will  be no interruption of her nerve signaling and she will have full range of motion in her arm.

•B. There will be no longer term effects; the dendrite will  self-heal  after 1-2 weeks and she will regain full motion

•C. She will  permanently lose motion in her entire upper body; damage to one dendrite will interrupt signaling in her upper body region

•D. She will l permanently lose motion in her right arm, the damage to the dendrite will make it so that signals will be unable to travel through the right arm’s nervous system

•E. She will temporarily lose motion in her right arm; the damage to the dendrite will have a direct effect on the axon of nerve cells  in her right arm causing her nerve cells to be able to signal to other nerve cells temporarily

(E) FRQ-Suppose a ball is thrown toward your head and you react by catching the ball, describe the process of your body transmitting the signal (the sight of the ball flying towards you) and how your nervous system processes this information and produces a response to it.


LO 3.44: The student is able to describe how nervous systems detect external and internal signalsSP 1.2: The student can describe representations and models of natural or man-made phenomena and systems in the domain

Explanation: The sensory nerve system (SNS) acts as an input device, transmitting information from all parts of the body to the central nervous system (CNS) through signals. Afferent (sensory) neurons carry these sensory signals from end organs to the CNS for processing and integration, by conducting impulses into the brain or spinal cord. End organs include muscles, glands, specialized senses, and skins, all which contain afferent neurons. The CNS then acts as a processing unit, where information is received, processed, and commands are issued for the response. The signals issued by the sensory neurons are transmitted through electrical and chemical signals. A nerve cell membrane at rest measures -70 mV, so the electrical charge outside the membrane is positive when the cell membrane is unstimulated, creating a resting membrane potential. However, when a nerve impulse causes the of channel proteins and the flow of Na+ ions into the cell, while K ions remain outside the membrane, a threshold value of -50 mV is reached. This causes ion gates in the membrane to open, allowing Na+ to rush into the cell and create an action potential, so a signal is sent from the sensory neurons to the CNS.

Learning Log/FRQ-Style Question:Ouabain, a plant substance used in some cultures to poison hunting arrows, disables the sodium-potassium pump. What change in the resting membrane potential would you expect to see if you treated a neuron with ouabain? Why?

M.C. Question: Action potentials are normally carried in one direction from the axon hillock to the axon terminals. By using an electron probe, you experimentally depolarize the middle of the axon to threshold. What do you expect?

No action potential will be initiated.

An action potential will be initiated and proceed in the normal direction toward the axon terminal.

An action potential will be initiated and proceed back toward the axon hillock.

Two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock.

An action potential will be initiated, but it will die out before it reaches the axon terminal.


LO 3.45: The student is able to describe how nervous systems transmit information.

SP 1.2: The student can describe representations and models of natural or man-made phenomena and systems in the domain.

Explanation: Animals nervous systems are made up of Central Nervous System (CNS) and Peripheral Nervous System (PNS). A signal is usually detected by PNS and sent to CNS which provides a response to be carried out by PNS. A neuron is the basic structure of Nervous Systems. Action potentials propagate electrical impulses along neurons when they reach the threshold and depolarize the membrane. The impulse triggers the cell to release certain chemical messengers called neurotransmitters to the adjacent cell across the synapse to produce a response which is either inhibitory or stimulatory.

M.C. Question: Which of the following is the correct order of sequence?

A) Resting state – depolarization – Na+ influx – K+ efflux

B) Na+ influx – depolarization – K+ efflux – resting state

C) Resting state – K+ efflux – Na+ influx – depolarization

D) K+ efflux – resting state – Na+ influx – depolarization

Learning Log/FRQ-style Question: Describe in details what happens between a presynaptic cell and a postsynaptic cell using the following terms: voltage-gated Ca2+ channel, Ca2+, synaptic vesicles, Na+/K+, ligand-gated ion channels, and neurotransmitters.


LO 3.46: The student is able to describe how the vertebrate brain integrates information to produce a response.

SP 1.2:The student can describe representations and models of natural or man-made

phenomena and systems in the domain.

Explanation: The brain provides the integrative power that underlies the complex behavior of vertebrates. The spinal cord integrates simple responses to certain kinds of stimuli (such as the knee-jerk reflex) and conveys the information to and from the brain. When the brain receives information, it is immediately processed. Sensory neurons transmit information from sensors that detect external stimuli (light, sound, heat, smell, and taste) and internal conditions (such as blood pressure, blood carbon dioxide level, and muscle tension). The information is sent to the CNS, where interneurons integrate the sensory input. Motor output leaves the CNS via motor neurons, which communicate with effector cells (muscle cells or endocrine cells).When experiencing a reflex, for example, the information is first received by dendrites extending from the cell body of the neuron. The signal is then generated at the axon hillock and transmits down the axon itself. At the end of the neuron, there are synaptic terminals, where the information is passed from the transmitting neuron (the presynaptic cell) to the receiving cell (the postsynaptic cell) by means of chemical messengers called neurotransmitters throughout the brain. These neurotransmitters in the presynaptic neurons bind to receptors in the postsynaptic neurons, and pass the signal onward. The sensory neurons convey the information to the spinal cord. They then communicate with interneurons that both inhibit and signal certain motor neurons that convey signals to a specific body part, producing a response.

M.C. Question: If the axon of a neuron was to be severed, what would most likely be the effect?

A) The neuron would be unable to receive information from another neuron.

B) The neuron would be unable to transmit information to another neuron.

C) It would have no effect, depending on which side of the axon that was severed.

D) The myelin sheath would break and the transmittance would slow down.

Learning Log/FRQ-style Question: It’s Halloween night and you go to a haunted house. While you are there, a masked character runs out and scares you. Without thinking, you punch the character in the face. This is considered a type of reflex. How does your brain integrate the information of fright and produce a response? How is this response created through the pathway of neurons and neurotransmitters? Be specific.


LO 3.47 The student is able to create a visual representation of complex nervous systems to describe and explain how these systems detect external and internal signals, transmit and integrate information, and produce responses.

SP 1.1 The student create representations and models of natural or man-made phenomena and systems in the domain.

Explanation: The neuron is the basic structure of the nervous system. It is comprised of an axon, cell body, and dendrites. External and internal signals send nerve signals through neurons from the peripheral nervous system to the central nervous system. A signal arrives at the dendrites , passes through the cell body and, if the signal reaches action potential, passes through the axon hillock and finally goes to the axon so that it can carry on the signal to another neuron. A signal reaches action potential if the membrane of the neuron is depolarized. The membrane of a neuron becomes depolarized if, after receiving a stimulus, sodium gated channels powered by ATP allow sodium ions to enter and cause a rise in the membrane potential. As a result, the rapid influx of sodium ions allows the polarity of the neuron membrane to be reversed. Potassium channels powered by ATP are also activated and they flow out of the cell, allowing for the action potential to return to resting potential. This entire action potential process allows for a response to occur that could include the release of excitatory or inhibitory neurotransmitters like GABA or acetylcholine or the transferring of a message from one neuron to the other through the synaptic gap, which would, in the end, allow for a physical response through motor neurons in the peripheral nervous system.

M.C. Question: Why are action potentials usually conducted in only one direction along an axon?

The nodes of Ranvier can conduct potentials in only one direction.

The brief refractory period prevents reopening of voltage-gated Na+ channels.

The axon hillock has a higher membrane potential than the terminals of the axon.

Ions can flow in only one direction

Learning Log/FRQ Style Question: If all the Ca+2 in the fluid surrounding a neuron were removed, how would this affect the transmission of information within and between neurons? Why?


LO 3.48: The student is able to create a visual representation to describe how nervous systems detect external and internal signals.

SP 1.1: The student can create representations and models of natural or man-made

phenomena and systems in the domain.

Explanation: For survival, an animal’s nervous system must detect external stimuli, process, and then respond to such stimuli accordingly. Sensory systems within the body have developed the ability to monitor and detect chemical and physical signals from the environment. The NS then interacts with these sensory and internal body systems to produce appropriate responses, from alterations in metabolic rate to triggering respiration. Nervous systems receive external information via sensory neurons, associated with the 5 senses, which consist of dendrites, a cell body, and an axon. Electrical signals generate impulses within these neurons through the creation of action potentials, in which Na+ and K+ gated ion channels open, allowing the neuron to become temporarily depolarized. Information is transferred from one neuron to the next via the movement of neurotransmitters, chemical signals, across a synapse. Transmission of this information results in a response, directed by the brain, that will call for changes in the body, whether it be, for example, muscle movement or hormone release.

M.C. Question: Suppose you were to draw an image of a neuron that had just received an electrical impulse. Which of the following would not be included in your drawing? Why?

Neurotransmitters, because they are not involved in nerve signaling.

Nothing. It is a chemical signal that travels down a neuron, not an electrical one.

ATP synthase, because neurons are not directly responsible for energy production.

Mitochondrion, because neurons do not have the organelles that regular cells have.

FRQ: Explain how a gazelle is able to run when being chased by a cheetah in terms of the nervous system response, and draw and label a visual representation of a nerve cell involved in the response.


LLO 3.49 :The student is able to create a visual representation to describe how nervous systems transmit information. SP 1.1: The student can create representations and models of natural or man-made phenomena and systems in the domainExplanation: The basic structure and function in the nervous system is called the neuron. Neuron is a long cell that consists of a cell body, dendrites and axon. The nervous system consists of central nervous system and peripheral nervous system. PNS carries impulses between the CNS and body. The nerve cells can be divided into three main classes. There are sensory neurons, interneuron and motor neurons. For instance when the body receives a stimuli, the touch stimulates sensory receptors located in skin which send a sensory impulse that is carried to the spinal cord. Interneuron process incoming impulses and pass response to the motor neurons. Motor neurons carry the response away from the brain and spinal cord to a muscle or gland. However, the impulses need to be transmitted from one nerve cell to another for it to be interpreted into a response. When a stimulus excites a neuron, gated sodium channels in the membrane open up. This allows sodium ions to enter the cell. The buildup of positive sodium ions inside the membrane causes the cell to become more positively charged inside than outside. Therefore, this cell is depolarized. If threshold potential is reached, and action potential is triggered. This causes potassium channels to open slowly. Na and K pumps are powered by ATP. After a while, the sodium gates slowly closes and potassium rushes out causing depolarization. Then the potassium channels slowly close. The impulse then moves to the end of the axon. Here the calcium channels open, allowing calcium to enter the end of the axon, the calcium causes vesicles in the axon to fuse with the plasma membrane, releasing their chemicals (neurotransmitters) into the synaptic space. The neurotransmitters diffuse across the space to the dendrites of the next neuron, this signals receptor sites to open the ion channels. The open channels change the polarity in the neuron, starting a new impulse. Myelin sheath insulates the axons increasing the speed at which the signal travels. The transmission of the impulses through nerve cells will cause a response to be elicited.

M.C. Question : Transmission across a synapse is achieved mainly by adiffusion of neurotransmitter across the cleft which is triggered specifically by?

The depolarization of membrane

The influx of Ca+ into the axon of sending neuron

The initial resting potential of the neuron

The insulation of axons by Schwann cells

FRQ- style question : Determine the function(s) of CA2+ in the transmission of

signals between neurons. How would the removal of CA+ from the synaptic cleft affect the way the

signals are transmitted?


SP 1.1 The student can create representations and models of natural or man-made phenomena and systems in the domain.

LO 3.50: The student is able to create a visual representation to describe how the vertebrate brain integrates information to produce a response.

M.C. Question: Which of the following cells are involved after the information is transferred to the CNS?

A) The sensory cells are sent by the sensory neurons to transfer the information to be integrated by the interneurons

B) The sensory cells are sent by the sensory neurons to stimulate muscles after information is processed by interneurons

C) The effector cells are sent by the motor neurons to transfer the information to be integrated by the interneurons

D) The effector cells are sent by the motor neurons to stimulate muscles after the information has been processed by the interneurons

Explanation: The nervous system undergoes three stages controlled by specific neurons while processing information. The first stage involves sensory neurons which take the information from the body’s sensors that detect a stimulus. These neurons can be triggered by external sources such as light or sound or by internal sources such as blood pressure changes. This sensory input is then transferred to the interneurons which analyze and interpret the information by taking into account the present and past situations. Once integrated, motor neurons are activated which work with effector cells to provoke a response from muscles. Neurons stay in resting potential until a stimulus causes sodium ions to flow into the cell, thus causing the usually negative internal area to become more positive. The cell is then depolarized and it is in action potential. Once the threshold is met, the signal is sent from the neuron to a neighboring receiving neuron. Potassium ions then flood out of the cell to repolarize it back to resting potential.

Learning Log/FRQ-style Question: Suppose that a doctor’s patient got into an accident in which her sensory neurons were damaged. How would the entire integration process be effected? Would a response still be elicited from a stimulus?