AP®︎ Biology: Unit 7 Practice Test
Prepare for your quiz, test, or the AP exam with focused practice questions on Unit 7 of AP Biology – Natural Selection.
Questions List
Unit 7 (All Topics)
Question 1 Topic 7.1Easy
This question tests the following: EVO-1.C
Which of the following best defines evolution?
What You’re Being Tested On:
Explore the learning objectives taken directly from the College Board’s AP® Biology Curriculum. Ensure you’re prepared for the exact topics covered on the AP® exam, in-class tests, and quizzes, and gain confidence in your mastery of the material.
Unit 7: Natural Selection
How populations change over time through natural selection, genetic drift, and speciation.
Topic 7.1: Introduction to Natural Selection
Learning Objective: 7.1.A
Describe the causes of natural selection.
Essential Knowledge: 7.1.A.1
Natural selection is a major mechanism of evolution.
Essential Knowledge: 7.1.A.2
According to Darwin’s theory of natural selection, competition for limited resources results in differential survival. Individuals with more favorable phenotypes are more likely to survive and produce more offspring, thus passing on those favorable traits to subsequent generations.
Learning Objective: 7.1.B
Explain how natural selection affects populations.
Essential Knowledge: 7.1.B.1
Evolutionary fitness is measured by reproductive success.
Essential Knowledge: 7.1.B.2
Biotic and abiotic environments can fluctuate, affecting the rate and direction of evolution. Different genetic variations can be selected in each generation.
Topic 7.2: Natural Selection
Learning Objective: 7.2.A
Describe the importance of phenotypic variation in a population.
Essential Knowledge: 7.2.A.1
Natural selection acts on phenotypic variations in populations.
Essential Knowledge: 7.2.A.2
Environments change and apply selective pressures to populations. Illustrative examples: Flowering time in relation to global climate change.
Essential Knowledge: 7.2.A.3
Some phenotypic variations can increase or decrease the fitness of an organism in particular environments. Illustrative examples: Sickle cell anemia; DDT resistance in insects.
Learning Objective: 7.2.B
Explain how variation in molecules within cells connects to the fitness of an organism.
Essential Knowledge: 7.2.B.1
Variation in the number and types of molecules within cells can provide populations a greater ability to survive and reproduce in different environments.
Topic 7.3: Artificial Selection
Learning Objective: 7.3.A
Explain how humans can affect diversity within a population.
Essential Knowledge: 7.3.A.1
Through artificial selection, humans affect variation in other species.
Topic 7.4: Population Genetics
Learning Objective: 7.4.A
Explain how random occurrences affect the genetic makeup of a population.
Essential Knowledge: 7.4.A.1
Evolution is also driven by random occurrences. i. Mutation is a random process that adds new genetic variation to a population. ii. Genetic drift is a change in allele frequencies attributable to a nonselective process occurring in small populations. iii. The bottleneck effect is a type of genetic drift that occurs when a population size is reduced to a small number of individuals for at least one generation. iv. The founder effect is a type of genetic drift that occurs when a population is separated from other members of the population. The frequency of genes and traits will shift based on the genes in this new founder population. v. Migration can result in gene flow (the addition or removal of alleles from a population).
Learning Objective: 7.4.B
Describe the role of random processes in the evolution of specific populations.
Essential Knowledge: 7.4.B.1
Random processes can lead to changes in allele frequencies in a population. i. Mutations result in genetic variation, which provides phenotypes on which natural selection acts. ii. Genetic drift can allow a small population to diverge from other populations of the same species. iii. Gene flow between two populations prevents them from diverging into separate species.
Learning Objective: 7.4.C
Describe the change in the genetic makeup of a population over time.
Essential Knowledge: 7.4.C.1
Changes in allele frequencies provide evidence for the occurrence of evolution in a population.
Topic 7.5: Hardy–Weinberg Equilibrium
Learning Objective: 7.5.A
Describe the conditions under which allele and genotype frequencies will change in populations.
Essential Knowledge: 7.5.A.1
The Hardy–Weinberg Equilibrium is a model for describing and predicting allele frequencies in a non-evolving population. Conditions for a population or an allele to be in Hardy–Weinberg equilibrium are: i. A large population size ii. No migration iii. No new mutations iv. Random mating v. No natural selection These conditions are never met, but they provide a valuable null hypothesis.
Essential Knowledge: 7.5.A.2
Allele frequencies in a nonevolving population can be calculated from genotype frequencies. Hardy–Weinberg Equation— p^2 + 2pq + q^2 = 1, and p + q = 1, where: p = frequency of allele 1 in the population q = frequency of allele 2 in the population. Illustrative examples: Graphic analysis of allele frequencies in a population.
Topic 7.6: Evidence of Evolution
Learning Objective: 7.6.A
Describe the types of data that provide evidence for evolution.
Essential Knowledge: 7.6.A.1
Evolution is supported by scientific evidence from many disciplines (geographical, geological, physical, biochemical, and mathematical data).
Learning Objective: 7.6.B
Explain how morphological, biochemical, and geological data provide evidence that organisms have changed over time.
Essential Knowledge: 7.6.B.1
Molecular, morphological, and genetic evidence from extant and extinct organisms adds to our understanding of evolution. i. Fossils can be dated by a variety of methods. These include 1) the age of the rocks where a fossil is found; 2) the rate of decay of isotopes including carbon-14; and 3) geographical data. ii. Morphological homologies, including vestigial structures, provide evidence of common ancestry.
Essential Knowledge: 7.6.B.2
A comparison of DNA nucleotide sequences and protein amino acid sequences provides evidence for evolution and common ancestry.
Topic 7.7: Common Ancestry
Learning Objective: 7.7.A
Describe structural and functional evidence on cellular and molecular levels that provides evidence for the common ancestry of all eukaryotes.
Essential Knowledge: 7.7.A.1
Structural and functional evidence indicates common ancestry of all eukaryotes. This evidence includes: i. Membrane-bound organelles ii. Linear chromosomes iii. Genes that contain introns
Topic 7.8: Continuing Evolution
Learning Objective: 7.8.A
Explain how evolution is an ongoing process in all living organisms.
Essential Knowledge: 7.8.A.1
All species have evolved and continue to evolve. Examples include: i. Genomic changes over time ii. Continuous change in the fossil record iii. Evolution of resistance to antibiotics, pesticides, herbicides, or chemotherapy drugs iv. Pathogens evolving and causing emergent diseases
Topic 7.9: Phylogeny
Learning Objective: 7.9.A
Describe the types of evidence that can be used to infer an evolutionary relationship.
Essential Knowledge: 7.9.A.1
Phylogenetic trees and cladograms show hypothetical evolutionary relationships among lineages that can be tested.
Essential Knowledge: 7.9.A.2
Phylogenetic trees show the amount of change over time calibrated by fossils or a molecular clock, whereas cladograms do not show time scale or the evolutionary difference between groups.
Essential Knowledge: 7.9.A.3
Traits that are either gained or lost during evolution can be used to construct phylogenetic trees and cladograms. The out-group represents the lineage that is least closely related to the remainder of the organisms in the phylogenetic tree or cladogram. i. Shared derived characters can be present in more than one lineage and indicate common ancestry. These are informative for the construction of phylogenetic trees and cladograms. ii. Molecular data typically provide more accurate and reliable evidence than morphological traits in the construction of phylogenetic trees or cladograms.
Learning Objective: 7.9.B
Explain how phylogenetic trees and cladograms can be used to infer evolutionary relatedness.
Essential Knowledge: 7.9.B.1
Phylogenetic trees and cladograms can be used to illustrate speciation that has occurred. The nodes on a tree represent the most recent common ancestor of any two groups or lineages.
Essential Knowledge: 7.9.B.2
Phylogenetic trees and cladograms can be constructed from morphological similarities of living or fossil species and from DNA and protein sequence similarities.
Essential Knowledge: 7.9.B.3
Phylogenetic trees and cladograms represent hypotheses that are constantly being revised based on evidence.
Topic 7.10: Speciation
Learning Objective: 7.10.A
Describe the conditions under which new species may arise.
Essential Knowledge: 7.10.A.1
Speciation occurs when two populations become reproductively isolated from each other.
Essential Knowledge: 7.10.A.2
The biological species concept provides a commonly used definition of a species for sexually reproducing organisms. It states that species can be defined as a group capable of interbreeding and exchanging genetic information to produce viable, fertile offspring.
Learning Objective: 7.10.B
Describe the rate of evolution and speciation under different ecological conditions.
Essential Knowledge: 7.10.B.1
Punctuated equilibrium is when evolution occurs rapidly after a long period of stasis. Gradualism is when evolution occurs slowly over hundreds of thousands or millions of years.
Essential Knowledge: 7.10.B.2
Divergent evolution occurs when adaptation to new habitats results in phenotypic diversification. Speciation rates can be especially rapid during times of adaptive radiation as new habitats become available.
Essential Knowledge: 7.10.B.3
Convergent evolution occurs when similar selective pressures result in similar phenotypic adaptations in different populations or species.
Learning Objective: 7.10.C
Explain the processes and mechanisms that drive speciation.
Essential Knowledge: 7.10.C.1
Sympatric speciation occurs in populations with geographic overlap. Allopatric speciation occurs in populations that are geographically isolated. Illustrative examples: Hawaiian Drosophila; Caribbean Anolis; Apple maggot Rhagoletis
Essential Knowledge: 7.10.C.2
Various pre-zygotic and post-zygotic mechanisms can maintain reproductive isolation and prevent gene flow between populations.
Topic 7.11: Variations in Populations
Learning Objective: 7.11.A
Explain how the genetic diversity of a species or population affects its ability to withstand environmental pressures.
Essential Knowledge: 7.11.A.1
The level of variation in a population affects population dynamics. i. The ability of a population to respond to changes in the environment is influenced by genetic diversity. Species and populations with little genetic diversity are at risk of decline or extinction. ii. Genetically diverse populations are more resilient to environmental perturbation because they are more likely to contain individuals that can withstand the environmental pressure. iii. Alleles that are adaptive in one environmental condition may be deleterious in another because of different selective pressures. Illustrative examples: California condors; Black-footed ferrets; Prairie chickens; Potato blight; Corn rust; Genetic diversity and selective pressures; Antibiotic resistance in bacteria (not all individuals in a diverse population are susceptible to a disease outbreak).
Topic 7.12: Origins of Life on Earth
Learning Objective: 7.12.A
Describe the scientific evidence that supports models of the origin of life on Earth.
Essential Knowledge: 7.12.A.1
The origin of life on Earth is supported by scientific evidence. i. Geological evidence reinforces models of the origin of life on Earth. ii. Earth formed approximately 4.6 billion years ago (bya). The environment was too hostile for life until about 3.9 bya, and the earliest fossil evidence for life dates to 3.5 bya. Taken together, this evidence provides a plausible range of dates for the origin of life.
Essential Knowledge: 7.12.A.2
The RNA world hypothesis proposes that RNA could have been the earliest genetic material. There are three assumptions: i. At some point in time, genetic continuity was assured by the replication of RNA. ii. Base-pairing is necessary for replication. iii. Genetically encoded proteins were not involved as catalysts.
