Unit 7 AP Bio

What is natural selection?

The process by which traits that enhance survival and reproduction become more common in successive generations.

What are the causes of natural selection?

Overproduction of offspring, variation among individuals, competition for resources, and differential survival and reproduction.

What role does phenotypic variation play in natural selection?

It provides the raw material for natural selection; individuals with traits better suited to the environment tend to survive and reproduce.

How do humans affect diversity in natural selection?

Through artificial selection, habitat destruction, pollution, and introduction of invasive species.

What is the effect of environmental changes on populations?

They apply selective pressures, changing allele frequencies in a population.

What factors change allele frequencies in populations over time?

Mutation, genetic drift, gene flow, and natural selection.

What is genetic drift, and how does it affect small populations?

A mechanism of evolution that has greater effects in small populations, including bottleneck and founder effects.

Define the bottleneck effect.

A drastic reduction in population size that causes loss of genetic diversity.

What is the founder effect?

A small group starts a new population with a different allele frequency than the original.

What are the conditions for Hardy-Weinberg equilibrium?

Large population, no migration, no mutations, random mating, and no natural selection.

What does the Hardy-Weinberg equation p² + 2pq + q² = 1 represent?

The frequencies of genotypes in a population: p² is the frequency of homozygous dominant, 2pq is heterozygous, and q² is homozygous recessive.

Which of the following supports the theory of common ancestry? (A) Similar climate tolerance, (B) Analogous traits, (C) Shared genetic code, (D) Different protein functions

(C) Shared genetic code.

What evidence supports evolution?

Fossil record, morphological homologies, and molecular homologies.

What is speciation?

The process when populations become reproductively isolated.

Differentiate between allopatric and sympatric speciation.

Allopatric speciation occurs due to physical barriers, while sympatric speciation involves genetic or behavioral isolation.

What are prezygotic barriers?

Prezygotic barriers prevent mating or fertilization, including habitat, temporal, behavioral, mechanical, and gametic barriers.

What are postzygotic barriers?

Postzygotic barriers occur after fertilization, including hybrid inviability and sterility.

What are the rates of speciation?

Gradualism (slow changes) and punctuated equilibrium (short bursts of change).

What can lead to extinction?

Environmental change, loss of genetic diversity, or human activity.

What is adaptive radiation?

Rapid speciation that occurs when niches open due to extinction or environmental changes.

What is the abiotic synthesis hypothesis?

The theory that early Earth had the conditions necessary to form organic molecules.

What is the RNA World Hypothesis?

The hypothesis that RNA was likely the first genetic material capable of storage, replication, and catalyzing reactions.

What evidence supports the origin of life theories?

Geological dating, the Miller-Urey experiment, and meteorites as probable sources of organic molecules.