BIOLOGY EOC PRACTICE TEST

1. BIOLOGY EOC PRACTICE TEST April 24, 2012

2. Yes, yes it is. 

3. 1. Prokaryotes are considered by the scientific community as the most ancient life-forms on Earth. Yet, these primitive cells share many common characteristics with the more modern eukaryotes. However, one significant difference between these two cell types is that only eukaryotes contain The correct answer is • A membrane-bound compartments to carry out specialized functions • B a selectively-permeable cell membrane to maintain homeostasis • C deoxyribonucleic acid to serve as a template to produce proteins • D a rigid cell wall which provides structure and support

4. EXPLANATION: Prokaryotic cells do not have any membrane organelles, which includes the nucleus. WORD PARTS: pro – before karyo - nucleus Choices B and C identify structures common to ALL cells. Choice D names a structure that only some cells have.

5. 2. What is the most likely cause of the potato core gaining mass when placed in the 0M sucrose solution? The correct answer is • A Sucrose moved into the potato core from the solution. • B Sucrose moved from a region of higher concentration to a region of lower concentration. • C Water moved down its concentration gradient. • D Water concentrations stayed the same inside and outside the potato core.

6. EXPLANATION C is the correct answer because • Only water is assumed to be able to move across a cell membrane (negating A and B) • Water moves down its concentration gradient (from high water concentration to low water concentration) so D cannot be correct • 0M sucrose means there is no sucrose, so A cannot be correct • If only water can move and mass went up, A can’t be correct, B can’t be correct, and D can’t be correct Potato core 0M solution

7. 3. The isotonic point in this potato core experiment is closest to • A 0M sucrose because sucrose moved into the potato core causing it to gain mass • B 0.2M sucrose because water didn’t move into or out of the potato core • C 0.2M sucrose because equal amounts of water moved into and out of the potato core • D 1M sucrose because the potato core lost the most mass due to water loss

8. EXPLANATION • Isotonic means that the concentration of the solution inside the cell (in this case potato cells) is the same as the concentration of the solution outside the cell (in this case the sucrose solution in the beaker). • When solutions are isotonic, there is no net movement of water (or solutes) and therefore the mass of the potato cores (cells) won’t change. • The only place the mass didn’t change is with the 0.2M solution WORD PARTS: iso – same hyper – above hypo – below tonic -

9. 4. Viruses are considered non-living because they lack the machinery to reproduce on their own and must rely on a cellular host cell to survive. Structures common to both cells and viruses include • A protein capsid • B nucleic acids • C cell wall • D nucleus

10. EXPLANATION • The answer is B nucleic acid because, as you can see on the chart above, viruses and cells both have DNA. A cell doesn’t have a protein capsid and a virus doesn’t have a cell wall. No viruses and only some cells have a nucleus.

11. 5. Differences between prokaryotes and eukaryotes which are readily observable through the light microscope includeI. prokaryotes are much smaller than eukaryotesII. ribosomes are smaller in prokaryotesIII. prokaryotes lack nuclei The correct answer is • A I only • B II only • C I and II only • D I and III only

12. EXPLANATION • The answer is D, I and III only because you can view the cells under the light microscope and see that the average prokaryotic cell is smaller than the average eukaryotic cell, as well as that there are nuclei in the eukaryotic cells but not in the prokaryotic cells. • You can not see ribosomes under the light microscope (and they wouldn’t appear different if you viewed them under an electron microscope even though they are slightly different…)

13. 6. Cells often need to take in materials from their environment, many of which are found in lower concentrations outside the cell compared to inside the cell. In order to do this, cells must use the energy from ATP to move these materials The correct answer is • A against the concentration gradient through active transport • B with the concentration gradient through active transport • C against the concentration gradient through passive transport • D with the concentration gradient through passive transport

14. EXPLANATION • A is the only correct answer. The question describes moving a material into the cell that is in lower concentration outside the cell. You should recognize this description as being AGAINST the concentration gradient (low to high) • Just like pushing a ball up a hill (from low to high) ENERGY is required. By definition, this makes it ACTIVE transport. DOWN/WITH, NO energy, PASSIVE UP/AGAINST, ENERGY, ACTIVE

15. 7. The cellular organelle most directly involved in maintaining homeostasis is the? The correct answer is • A plasma membrane • B cell wall • C chloroplast • D mitochondria

16. EXPLANATION • The correct answer is A plasma membrane because the primary role of the plasma membrane is to regulate what comes in to and goes out of a cell. As the environment changes, so does what goes in and out. • The primary functions of the other structures are support/shape, photosynthesis, and cellular respiration, respectively

17. 8. Viruses are able to infect cells because they share a common genetic code and are able to use host cell enzymes to carry out protein synthesis. There are some structures which are unique to viruses and not found in cells. These includeI. Protein capsidII. Nucleic acidsIII. Cell wall The correct answer is • A I only • B II only • C I and II only • D II and III only

18. EXPLANATION • The correct answer is protein capsid only. Both cells and viruses have nucleic acids. Only cells have cell walls.

19. 9. During an infection, some viruses remain inside the cell but do not cause symptoms of disease. The graphic depicts the The correct answer is • A lytic cycle and the host cell is destroyed by rapidly reproducing viral particles • B lytic cycle and the viral nucleic acid inserts into the host cell chromosome • C lysogenic cycle and the viral nucleic acid inserts into the host cell chromosome • D lysogenic cycle and the viral nucleic acid replicates independently of the host cell chromosome

20. EXPLANATION • The diagram on the top shows the cycle from the question. The diagram on the bottom shows the other possibility. It is important that you note that both A and D should be immediately eliminated because the cell is not destroyed and the nucleic acid is not replicating independently in the diagram. • That narrows your choices to B and C – lytic or lysogenic. One way you can remember it is that it takes much longer to go through the lysogenic cycle, and it’s the longer word.

21. 10. The stage of the cell cycle pictured may be best described as The correct answer is • A Cytokinesis: the cytoplasm of the cell is divided • B S phase: DNA is copied, resulting in identical sister chromatids • C G2 phase: the cell grows in size and prepares to divide the nucleus • D Mitotic phase: the nucleus is divided

22. EXPLANATION 2 nuclei 1 nucleus • The answer is D because it is showing the division of the nucleus. • It is not A because it has not divided into 2 cells yet. It is not B because the S phase happened before these pictures and is not shown. It is not C because the nucleus is actively dividing and the cell is not resting and growing

23. Laugh break!

24. 11. Leaves are plant organs specialized for photosynthesis. Through the light microscope, which organelle would be expected to be seen in greater numbers? The correct answer is • A mitochondrion. • B chloroplast. • C Golgi. • D vesicle

25. EXPLANATION • The key to this question is the phrase “ in greater numbers”. • The cells of the leaf of a plant are going to have all 4 structures mentioned. The mitochondrion is for cellular respiration, the Golgi is involved in protein manufacture and transport. The vesicle is involved in transport around the cell. • However, because it is a leaf cell and the leaf is the organ of photosynthesis, you would expect the cells to have a lot of chloroplasts relative to other cells.

26. 12. Each of the following statements describes the importance of the cell cycle and mitosis to an organism EXCEPT? The correct answer is • A The cell cycle and mitosis are important to produce identical new cells so that a multi-cellular eukaryote can grow larger. • B The cell cycle and mitosis are important to produce identical new cells so that a unicellular eukaryote can reproduce. • C The cell cycle and mitosis are important to produce identical new cells so that a multi-cellular eukaryote can repair damaged tissue. • D The cell cycle and mitosis are important to produce identical new cells so that a multi-cellular eukaryote can reproduce.

27. EXPLANATION • Mitosis has 3 important functions: • growth • repair • asexual reproduction of unicellular organisms • Multicellular organisms can not reproduce asexually through mitosis • only cells can undergo mitosis, not an organism • asexual reproduction in multicellular organisms is referred to by other names such as fragmentation & vegetative propagation

28. 13. According to the illustration, adult stem cells extracted from bone marrow tissue may be cultured to produce different types of differentiated cells, such as liver cells, nerve cells, and heart muscle cells. Which of the following statements can best explain this result? The correct answer is • A There are different genes in each of the individual stem cells that are cultured. • B Environmental conditions influence which genes are expressed. • C Each stem cell contains only the DNA required to make one cell type. • D DNA can move from one stem cell to another through the culture media.

29. EXPLANATION • This diagram shows adult stem cells from bone marrow producing a wide variety of cells, including muscle, nerve, and liver. The key to answering this question correctly is not to get hung up on “can they do that?” but to think about how different kinds of cells are created. • ALL cells have the entire set of chromosomes with all of the genes present; however, not all of the genes are expressed in every cell. • Stem cells retain the ability to change which genes are being expressed based on the signals received from outside the cell and therefore can become different types of cells.

30. 14. When harmful mutations occur in genes that contain the information to make cell cycle regulatory proteins, this may result in accelerated cell division. The result of these mutations is most likely The correct answer is • A cancer • B slower cell growth • C a halt in mitosis • D entry into G0 phase

31. EXPLANATION • Your book explains the functioning of the cell cycle checkpoints using the analogies of a stuck accelerator and having no brakes. • If a signal molecule that tells the cell “divide” gets produced too much, it’s like having the accelerator stuck • If another protein is supposed to stop or slow down cell division, it’s like having no brakes. CANCER – is when cells divide uncontrollably.

32. 15. Which of the illustrations depicts a nucleotide, the building block of DNA? The correct answer is • A guanine base only. • B thymine base only. • C nucleotide. • D phosphate group.

33. EXPLANATION • A nucleotide has 3 parts; if it doesn’t have all 3 parts, it’s not a nucleotide • 5-carbon sugar (either ribose or deoxyribose) • Nitrogen base (thymine, adenine, cytosine, guanine, uracil) • Phosphate group

34. 16. Which statement most accurately describes how deoxyribonucleic acid (DNA) carries the genetic code for building an organism? The correct answer is • A The order of nitrogen bases provides the genetic code • B The genetic code is based on the number of hydrogen bonds found between nitrogen bases • C The number of deoxyribose sugars along the sides of the DNA ladder is used to determine the genetic code • D The shape of the DNA molecule provides the genetic code

35. EXPLANATION • What you have learned about transcription and translation (protein synthesis/ gene expression) as well as mutations should be enough to remind you that the genetic code is in the sequence of the nucleotides of the DNA; i.e. • ATTCGGTAAATTGGCCC does NOT say the same thing as ATTGCCTAAATTGGCCC because CGG and GCC do not code for the same amino acid!

36. 17. Which of the following structures would pair with the nitrogen base adenine in a complementary strand of DNA? The correct answer is • A guanine • B thymine • C nucleotide. • D phosphate group.

37. EXPLANATION • The base-pairing rules, based on Chargoff’s research, are • A-T, G-C

38. 18. Restriction enzymes isolated from various bacterial species have been extensively used in the biotechnology laboratory for cutting human genes from DNA samples to insert into bacterial plasmids. This is made possible because The correct answer is • A Nitrogen bases form a common genetic code for all organisms. • B DNA is maintained in both bacterial and human cells within nuclear membranes. • C Small, circular pieces of DNA called plasmids are common to both humans and bacteria. • D Restriction enzymes cut at random sequences so it does not matter that humans and bacteria use a different genetic code.

39. EXPLANATION • A is correct because there is only one genetic code for all organisms and almost without exception, the same sets of 3 nucleotides (codons) code for the same amino acids, therefore human proteins can be produced by bacteria (we currently do this with insulin and human growth hormone) • The other answers are not correct because • bacteria do not have nuclear membranes • eukaryotic cells do not have plasmids • restriction enzymes do not cut at random places

40. 19. The model in the graphic illustrates translation, the latter part of the process of protein synthesis. Which other necessary components for translation are absent from the graphic? The correct answer is • A messenger RNA and transfer RNA • B ER membranes and ribosomes • C ribosomal RNA and DNA • D transfer RNA and ribosomes

41. EXPLANATION • The picture on the test (above) shows just a section of mRNA. For translation to occur, a ribosome must be present, as well as the tRNA molecules needed to bring the amino acids for the growing polypeptide. More like the picture below RIGHT: Translation in the cytoplasm at the ribosome (structure 3) Structure 1 - nuclear envelope Structure 2 – mRNA Structure 3 – ribosome Structure 4 – polypeptide (amino acid chain; protein) Structure 5 – tRNA with amino acid

42. 20. Which of the following statements is NOT correct regarding the process in the illustration? The correct answer is • A I must be complementary to an mRNA codon. • B This process occurs in the nucleus of a cell. • C III shows the first two amino acids of a growing polypeptide chain. • D The process shown is translation.

43. EXPLANATION • The question wants to know which statement is NOT true – this IS showing translation, Roman numeral I is pointing to the anticodon, which must be complementary to a codon, and Roman numeral III is pointing to the first 2 amino acids in the chain • HOWEVER, translation occurs in the cytoplasm at the ribosome, NOT in the nucleus. Transcription (DNA RNA) is in the nucleus

44. Ever feel this way?

45. 21. Bacterial species’ genomes are arranged somewhat differently than those of eukaryotes. Their circular chromosome contains clusters of genes which code for proteins that work together to accomplish a series of related tasks. In this way, groups of genes can be turned on when the gene product(s) are needed, and turned off when they aren’t needed. This confirms the fact that The correct answer is • A gene expression is a regulated process. • B genes are arranged similarly in prokaryotes and eukaryotes. • C eukaryotes have circular chromosomes. • D bacterial genomes are much larger than those of eukaryotes.

46. EXPLANATION • This is a tough question. The answer is that gene expression is a regulated process. You might have discussed the lac and trp operons in your Biology class and remembered that the genes that code for the breakdown of lactose or the synthesis of tryptophan can be turned on and off as the cell needs those things to be done. • If not, here are some other things you might have known: • Genes are on linear chromosomes in eukaryotes (like you); think about the karyotypes we looked at in the genetics unit • Bacterial genomes (the one big ring) are MUCH smaller than all of the chromosomes in a eukaryote combined, which is what a genome is – all of the genetic material in an organism

47. 22. Changes in DNA sequences are called mutations. Mutations may affect only one nitrogen base in the sequence,or may affect large regions of a chromosome. The particular type of gene mutation that is illustrated is called a The correct answer is • A point mutation • B insertion mutation • C frameshift mutation • D nonsense mutation

48. EXPLANATION • On this question, you must remember that you are looking for the BEST answer. • Frameshift mutation is the BEST answer because it is the most specific and accurate • It is a point mutation, but that is less specific • It is NOT an insertion, it’s the opposite, a deletion • It is not a nonsense mutation because it did not result in a premature stop codon that can be seen on the page

49. 23. The significance of this gene mutation is that The correct answer is • A A different amino acid sequence results which is likely to affect the functioning of the final protein product. • B A different amino acid sequence results which is not likely to affect the functioning of the final protein product. • C No protein product will be produced. • D The protein product is unaffected

50. EXPLANATION • This question refers to the same diagram we were just looking at. Let’s start with the WRONG answers. • D is clearly wrong because if you look at the 2 amino acid sequences, there is a change • C is wrong because a protein is forming (a chain of amino acids is a protein), it’s just not the same one • B is wrong because protein function is VERY closely related to protein structure and it is NOT LIKELY that you can make changes and it still function normally. Think about the one amino acid change that results in sickle cell anemia or how important enzyme structure is to enzyme function