bio unit 7

1. How do humans affect diversity in a population?

→ Through artificial selection, humans choose traits, reducing or increasing variation.

2. What is the relationship between environment changes and evolution?

→ Convergent evolution happens when different species develop similar traits due to similar environmental pressures.

3. How do random events affect evolution?

→ Mutation, genetic drift (in small populations), and migration (gene flow) change genetic makeup randomly.

4. What happens when genetic variation is reduced in a population?

→ Differences between populations increase, leading to greater diversity between them.

5. How does a population’s genetic makeup change over time?

→ Mutations create variation. Natural selection acts on these variations.

6. What are the conditions for Hardy-Weinberg Equilibrium?

→ No evolution happens if:

Large population

No migration

No mutations

Random mating

No natural selection

Equation:

p² + 2pq + q² = 1

p + q = 1

7. What happens if Hardy-Weinberg conditions are not met?

→ Evolution occurs — allele frequencies change, especially in small populations.

8. What evidence supports evolution?

→ Data from:

Fossils

Morphological similarities

DNA & protein comparisons

9. How do molecular and morphological data show evolution?

→ Fossils show changes over time. DNA/protein similarities show common ancestry.

10. What evidence supports common ancestry across life?

→ Shared molecular features:

Membrane-bound organelles

Linear chromosomes

Genes with introns (in eukaryotes)

11. How is evolution ongoing?

→ Populations evolve through:

Genomic changes

Fossil record evidence

Resistance to antibiotics/pesticides

Emerging diseases

12. What tools show evolutionary relationships?

→ Phylogenetic trees & cladograms — show common ancestors and evolutionary paths.

13. How does speciation occur?

→ When populations become reproductively isolated — can no longer produce fertile offspring together.

14. What are the rates of evolution?

→ Punctuated equilibrium = rapid change

Gradualism = slow, steady change

15. What drives speciation?

→ Sympatric (same area) or allopatric (different areas) isolation, with barriers preventing gene flow.

16. What causes extinction?

→ Environmental stress, human activity, loss of habitat, competition.

17. How does extinction affect ecosystems?

→ New niches open → adaptive radiation occurs (new species evolve to fill them).

18. How does genetic diversity affect survival?

→ High genetic diversity = better survival in changing environments.

Low diversity = higher risk of extinction.

19. What evidence supports the origin of life on Earth?

→ Earth formed ~4.6 billion years ago. Life likely began ~3.5-3.9 billion years ago from inorganic molecules or through meteorites carrying organic material.

  1. What is evolution characterized by?

A change in the genetic makeup of a population over time, supported by multiple lines of evidence.

  1. What is the major mechanism of evolution?

Natural selection.

  1. According to Darwin’s theory, what causes differential survival?

Competition for limited resources — individuals with more favorable traits are more likely to survive and reproduce.

  1. What is evolutionary fitness measured by?

Reproductive success.

24. How do biotic and abiotic environments affect evolution?

they can fluctuate, affecting the rate and direction of evolution. Different genetic variations can be selected in each generation.

  1. Why is phenotypic variation important in a population?

It allows natural selection to act on differences in traits within a population.

  1. how do environments affect populations?

Environments change and apply selective pressures to populations.

  1. What happens to phenotypic variations in certain environments?

Some variations significantly increase or decrease the fitness of an organism depending on the environment.