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Stuff you need to know…. Genetics. Meiosis- cell division that forms gametes (sex cells  sperm or egg ) Will form 4 genetically different cells Haploid- 1 copy of the chromosomes (gametes), human haploid #= 23

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  • Meiosis- cell division that forms gametes (sex cells sperm or egg)
    • Will form 4 genetically different cells
  • Haploid- 1 copy of the chromosomes (gametes), human haploid #= 23
  • Diploid- 2 copies of the chromosomes (all the rest of your cells), human diploid #= 46

Homologous pairs- one chromosome from mom and one from dad (PROPHASE I)

  • Crossing over- homologous pairs touch during meiosis and swap DNA, increases genetic diversity (PROPHASE I)

Gregor Mendel- Father of Modern genetics, known for his work with pea plants

  • Genes- sequences of DNA that code for proteins (Ex: flower color or hemoglobin)
  • Alleles- forms of the gene; specific instructions (Ex: “normal” hemoglobin or “mutated” hemoglobin; “A” or “a”)
  • Genotype- inherited genetic make-up (AA, Aa, or aa)
  • Phenotype- what you physically express (normal vs mutated; purple vs white flowers; tall versus short pea plants)

Homo = same

  • Homozygous dominant- AA
  • Homozygous recessive- aa
  • Hetero= different
  • Heterozygous- Aa
  • Punnett squares- uses parent’s gametes to predict probable genetic outcomes of offspring

Round (R) is dominant over wrinkled (r) seeds. Cross 2 heterozygous pea plants for seed shape.

  • What are the

chances the

offspring will

express the

recessive trait?


Dad is heterozygous and mom is homozygous recessive. What are the chances their offspring will express the dominant trait?


Sex-Linked Genes: genes that are on the X or Y chromosome

*because any gene on the Y chromosome will always affect males & only males, these problems only discuss genes on the X chromosome

*females have 2 X chromosomes & males have 1 therefore, males are more likely to exhibit recessive phenotypes from sex-linked genes


·EVOLUTION: cumulative change in the heritable characteristics of a population


·FITNESS: refers to traits and behaviors of organisms that enable them to survive and reproduce

·ADAPTATION: any inherited characteristic that enhances an organism’s ability to survive and reproduce in that particular environment

~based on variations randomly inherited (mutation & meiosis)

charles darwin s explanation on evolution six major ideas of darwin
Charles Darwin’s Explanation on Evolution (six major ideas of Darwin)

Not all organisms can survive

Overproduction occurs in nature

Variation occurs in all populations

Variations are inherited

Organisms with favorable variations survive and reproduce

Populations as a whole become FIT = evolved!

genetic drift
Genetic Drift

Changes in the gene pool (# or % of “A” allele vs “a” allele) of a small population due to chance; REDUCES VARIATION


-Bottleneck Effect: results from drastic decrease in population size

-Founder Effect: few individuals in a population colonize a new habitat


The origin of new species (the appearance of new species is the source of biological diversity)

  • Reproductive Isolation: barriers that prevent members of two species from producing viable, fertile hybrids
Geographic Isolation: Gene flow between gene pools is interrupted when a population is divided into two geographically isolated subpopulations
    • Ex: the water level in a lake decreases
    • Ex: a river splits a population into two
1 life is organized on many structural levels

1) Life is ORGANIZED on many structural levels:


Biological Molecules

Subcellular organelles




Organ Systems

Complex Organism

levels beyond the individual organism

Levels beyond the individual organism:






  • Definition: the number and variety of organisms found within a specified geographic region
    • affected by alterations of habitats.
fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.
    • Change in pop size = [B + I] – [D + E]
  • Autotrophs—capture energy from sunlight or chemicals and use that energy to produce food
    • AKA producers
      • Photosynthesis
        • Plants
      • Chemosynthesis
        • Bacteria
Heterotrophs (Consumers)
    • Herbivores
    • Carnivores
    • Omnivores
    • Detritivores
      • Feed on plant and animal remains (have a mouth; ingest food)
        • Mites, earthworms, snails
    • Decomposers
      • Break down organic matter
        • Bacteria and fungi
flow of energy
Flow of Energy

Energy flows through an ecosystem (a section of the biosphere) from the sun, to producers, to consumers


food chains
Food Chains
  • Food Chain—transfer of energy by eating and being eaten
food webs
Food Webs
  • Food Web—describes complex relationships of organisms in an ecosystem
    • A food web links together all the food chains in an ecosystem
energy pyramid
Energy Pyramid

Tertiary Consumers

Primary Consumers

  • each step of an organism eating another organism is called a trophic level (trophe means food in Greek)
  • Shows the relative amounts of energy contained within each trophic level in a food chain or food web
  • Only part of the energy that is stored in one trophic level is passed on…(10%)


Approximately 10% of the energy at one trophic level can be used by animals at the next trophic level
    • ex: 90% of produced/consumed energy is used in that organisms cellular respiration
    • Only 10% incorporated into tissues
More energy efficient to eat producers
  • Although energy moves in a one-way direction through an ecosystem, nutrients are recycled
  • series of changes in an ecological community that occur over time after a disturbance
    • Primary: have to make soil
    • Secondary: have soil; start from there

Fossils-Any preserved evidence of life from a past geological age (ex: impressions & remains of organisms embedded in stratified rocks; mineralized remains of an animal or plant

Fossils include shells, imprints, burrows, and organically-produced chemicals. The oldest fossils are of bacteria (prokarytotes) & they are 3.8 billion years old.