Common Ancestry

What is an adaptation?

• A trait that helps an organism survive and reproduce
• A random mistake in DNA
• The total number of organisms in an area
• A learned behavior

Answer explanation

Adaptations are heritable traits that improve survival or reproduction.

What is natural selection?

• The process where organisms with beneficial traits survive and reproduce more successfully
• Random mating between organisms
• Human influence on species
• A change in an individual’s lifetime

Answer explanation

Natural selection increases the frequency of advantageous traits in a population.

What does variation mean?

• Differences in traits among individuals in a population
• All members being exactly the same
• A sudden population increase
• Traits changing within one lifetime

Answer explanation

Variation is the raw material on which natural selection acts.

What is speciation?

• The formation of a new species when populations become isolated and evolve separately
• A sudden mutation in DNA
• Adaptation to a new environment
• Migration of a population

Answer explanation

Isolation + independent evolution can lead to new species.

What does common ancestry mean?

• Different species share a common ancestor from the past
• Species are unrelated
• Species never change
• Organisms only evolve once

Answer explanation

Different species branched from shared ancestors over time.

What are homologous structures?

• Structures with similar form but different function, showing a shared ancestor
• Structures with similar function but different form
• Structures that have identical DNA
• Unrelated body parts

Answer explanation

Homologous = same structure, different function → shared ancestry.

What are analogous structures?

• Structures with similar function but different form, showing no shared ancestor
• Structures with similar form and same function
• Identical DNA structures
• Shared embryonic development

Answer explanation

Analogous = same function, different structure → not from a shared ancestor.

What is the fossil record?

• Physical evidence showing how organisms have changed over time
• DNA found in living organisms
• Drawings of ancient life
• Structures in embryos

Answer explanation

Fossils provide a timeline of evolutionary change.

What does embryology show?

• Similar early development across species indicates shared ancestry
• Species evolve instantly
• Embryos are identical at all stages
• Mutations in adulthood cause evolution

Answer explanation

Early embryo similarities suggest common ancestry.

What is DNA evidence?

• Comparing DNA sequences shows how closely related species are
• Observing fossil bones
• Studying animal behavior
• Examining climate data

Answer explanation

More similar DNA = more recent common ancestor.