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Quizzes > High School Quizzes > Science

AP Bio Unit 6 MCQ Practice Quiz

Engage with diverse units MCQs for exam success

Difficulty: Moderate
Grade: Grade 12
Study OutcomesCheat Sheet
Colorful paper art promoting AP Bio MCQ Blitz quiz for advanced high school biology students.

What is the primary mechanism of natural selection?
Genetic drift over time
Differential survival and reproduction of individuals
Random mutations that always increase fitness
Gene flow from one population to another
Natural selection is driven by differences in individuals' ability to survive and reproduce in a given environment. Over time, favorable traits become more common because they enhance fitness.
Which of the following best defines an adaptation?
A feature that helps an organism interact with its environment regardless of its impact on fitness
A random mutation with no impact on an organism's survival
A heritable trait that increases an organism's survival and reproduction
A learned behavior passed from one generation to the next
Adaptations are inherited traits that help organisms survive and reproduce in their specific environments. These beneficial traits are shaped by natural selection and passed down through generations.
Which of the following is considered evidence for evolution?
Cultural traditions
Homologous structures
Mythological stories
Random weather events
Homologous structures in different species indicate a common ancestry, which supports the theory of evolution. These anatomical similarities result from evolutionary modifications over time.
What defines speciation?
The formation of a new allele within a single population
The migration of individuals from one population to another
The change in frequency of alleles over time
The process through which one species splits into two or more separate species
Speciation is the evolutionary process by which populations evolve to become distinct species. It typically occurs when genetic differences accumulate, often due to isolation, leading to reproductive barriers.
Which mechanism causes random changes in allele frequencies, particularly in small populations?
Natural selection
Mutation
Genetic drift
Gene flow
Genetic drift refers to random fluctuations in allele frequencies due to chance events, especially in small populations. Unlike natural selection, it is not driven by differences in fitness.
Which of the following is NOT a condition required for Hardy-Weinberg equilibrium?
Non-random mating
No migration
No mutation
Large population size
Hardy-Weinberg equilibrium assumes random mating, so non-random mating disturbs the equilibrium. The other options are essential conditions for maintaining equilibrium.
Which factor is least likely to cause evolutionary change in a population?
Random mating
Nonrandom mating
Mutations
Genetic drift
Random mating is one of the conditions for Hardy-Weinberg equilibrium and does not alter allele frequencies by itself. The other factors can lead to changes in allele frequencies over time.
Which best describes genetic drift?
A process where alleles are passed preferentially to offspring
The non-random reproduction of individuals with high fitness
A random change in allele frequencies that is more pronounced in small populations
Migration of individuals between populations
Genetic drift is a random process that leads to fluctuations in allele frequencies, particularly in small populations. This randomness distinguishes it from other evolutionary forces like natural selection.
Which event is most likely to lead directly to the formation of new species?
Natural selection in a monomorphic population
Genetic drift in a stable environment
Mutation within a large, panmictic population
Allopatric speciation due to geographic isolation
Allopatric speciation occurs when populations become geographically isolated, which prevents gene flow and allows divergent evolution. Over time, these isolated populations accumulate differences that result in new species.
How does gene flow influence the genetic diversity of populations?
It has no impact on genetic diversity.
It reduces genetic diversity by eliminating rare alleles.
It always leads to genetic drift.
It increases genetic diversity by introducing new alleles.
Gene flow involves the transfer of genetic material from one population to another, which can introduce new alleles and increase genetic diversity. This process reduces differences among populations by homogenizing allele frequencies.
During natural selection, how does differential reproductive success affect allele frequencies?
The allele frequencies remain constant due to balanced selection.
Unfavorable alleles dominate due to random chance.
Allele frequencies become unpredictable as a result of mutations.
Favorable alleles become more common in the population over time.
Individuals with traits that enhance survival and reproduction pass those advantageous alleles to their offspring at a higher rate. Over many generations, this selective pressure increases the frequency of beneficial alleles in the population.
Which process can counteract the effect of natural selection by homogenizing differences between populations?
Sexual selection
Gene flow
Genetic drift
Mutation
Gene flow involves the exchange of genetic material between populations, which tends to reduce genetic differences by mixing alleles. This process can counterbalance the diversifying effects of natural selection when populations interbreed.
What role do mutations play in evolution?
They introduce new genetic variations into a population.
They are balanced by natural selection and do not affect evolution.
They remove alleles from a gene pool.
They always result in harmful effects that lower fitness.
Mutations are changes in the genetic material that create new alleles, providing the essential raw material for evolutionary processes. While many mutations are neutral or deleterious, some confer advantages that can be favored by natural selection.
Which scenario is an example of convergent evolution?
The backbone in fish and mammals
Camera-like eyes in vertebrates and cephalopods
Forelimb structures in mammals and birds
Beak shapes in different species of finches
Convergent evolution occurs when unrelated species independently evolve similar traits in response to similar environmental pressures. The development of camera-like eyes in both vertebrates and cephalopods is a classic example, as these structures evolved independently.
How can environmental changes influence the evolution of a species?
They can create new selective pressures that favor different traits.
They have no impact since evolution is solely driven by genetic drift.
They only affect the behavior, not the genetics of a species.
They always lead to extinction without any evolutionary adaptation.
Environmental changes can alter the selective pressures acting upon a species, favoring traits that improve survival in the new conditions. These new pressures can drive evolutionary change as populations adapt over time.
How does sexual selection differ from natural selection?
Sexual selection only operates in mating rituals, whereas natural selection only influences physical traits.
Sexual selection is driven by predators, whereas natural selection is driven by mates.
Sexual selection results in random changes in allele frequencies, unlike natural selection.
Sexual selection focuses on traits that enhance mating success, while natural selection focuses on overall survival and reproduction.
Sexual selection specifically targets traits that improve an individual's ability to attract or compete for mates, which may not necessarily improve survival. In contrast, natural selection encompasses all traits that enhance overall fitness, including both survival and reproduction.
In a small, isolated population, what effect does the founder effect have on genetic diversity?
It maintains high genetic diversity by preventing inbreeding.
It has no impact on genetic diversity.
It decreases genetic diversity due to limited alleles being represented.
It increases genetic diversity by introducing many new alleles.
The founder effect occurs when a small group of individuals establishes a new population, carrying only a subset of the genetic variation from the original population. This bottleneck can lead to decreased genetic diversity and may increase the frequency of rare alleles.
What does the Hardy-Weinberg equation imply about an ideal, non-evolving population?
Allele frequencies change rapidly in response to environmental pressures.
Allele and genotype frequencies remain constant from generation to generation.
Allele frequencies increase due to constant mutation rates.
Genotype frequencies are unpredictable and fluctuate widely.
The Hardy-Weinberg equilibrium model predicts that in an ideal population - one without evolutionary influences such as mutation, selection, or drift - allele and genotype frequencies remain steady over time. This principle serves as a baseline for detecting when evolution is occurring.
How can a beneficial mutation become fixed in a population despite genetic drift?
By random chance in very large populations where drift is negligible.
Through positive selection where the mutation confers a significant fitness advantage.
Due solely to the overwhelming effect of gene flow.
Because beneficial mutations automatically spread to every individual.
A beneficial mutation that provides a strong fitness advantage is likely to increase in frequency through positive selection, eventually becoming fixed in the population. While genetic drift can influence allele frequencies, the selective advantage plays a dominant role in this scenario.
Which scenario best illustrates disruptive selection?
A gradual change in beak size over generations toward a moderate size.
An isolated population where a single trait becomes uniformly common due to random factors.
A population of insects where all individuals converge on a similar size due to environmental constraints.
A population of birds with both very small and very large beaks, where birds with intermediate beaks are less common.
Disruptive selection favors individuals at both extremes of a trait distribution while selecting against those with intermediate values. This can lead to a bimodal distribution within the population and may eventually result in speciation.
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Study Outcomes

  1. Analyze cellular structures and their functions in biological systems.
  2. Interpret genetic data and patterns of inheritance.
  3. Apply concepts of energy transformation and metabolism to biological scenarios.
  4. Evaluate experimental methodologies and data in biological research.
  5. Understand ecological interactions and evolutionary adaptations through applied problem-solving.

AP Bio Unit 6 MCQ Cheat Sheet

  1. DNA Double-Helix & Base Pairing - Picture your favorite twisted ladder: that's DNA's double-helix! The rungs are A pairing with T and G pairing with C, ensuring a perfect match every time for accurate information storage and replication. Learn-Biology AP Bio Guide
  2. Semi-Conservative DNA Replication - Every new DNA molecule keeps one old strand and one fresh strand, thanks to helicase unzipping the helix and DNA polymerase building new strands in the 5' to 3' direction. Don't forget ligase stitching up any gaps like a biological seamstress! Learn-Biology AP Bio Guide
  3. Transcription & Translation Workflow - In transcription, DNA scripts an mRNA copy; in translation, that mRNA is decoded by ribosomes into an amino acid chain. tRNA brings the right amino acids, turning genetic code into living proteins. Learn-Biology AP Bio Guide
  4. Prokaryotic Gene Regulation (Operons) - Bacteria use operons like on/off switches to control gene clusters - think of the lac operon flipping on when lactose shows up. This adaptive system saves energy and resources in changing environments. Learn-Biology AP Bio Guide
  5. Eukaryotic Gene Regulation - Eukaryotes fine-tune genes with transcription factors and epigenetic tags like DNA methylation or histone acetylation. These modifications can silence or spotlight genes without altering the underlying DNA letters. Learn-Biology AP Bio Guide
  6. Mutations & Their Impact - A single base swap can rewrite a whole story - like the point mutation in hemoglobin leading to sickle cell anemia. Understanding mutation types helps you predict how proteins might fold or malfunction. BioInteractive Resources
  7. Horizontal Gene Transfer - Bacteria borrow genes from neighbors through transformation, transduction, or conjugation, creating rapid genetic diversity. This microbial gene swap explains how antibiotic resistance can spread in a flash. Learn-Biology AP Bio Guide
  8. Biotechnology & CRISPR - Modern tools like CRISPR-Cas9 let scientists snip and rewrite DNA with surgical precision, opening doors to gene therapies and engineered crops. It's like having molecular scissors guided by a customizable GPS. Learn-Biology AP Bio Guide
  9. Virus Structure & Replication - Viruses are genetic pirates hijacking host cells to churn out new viral particles. Knowing capsid designs and replication tricks is critical for anti-viral strategies and vaccine development. Learn-Biology AP Bio Guide
  10. The Central Dogma - DNA → RNA → Protein sums up the flow of genetic information in every living cell. This elegant framework underlies everything from enzyme action to your brilliant brainpower. YouTube Summaries: Central Dogma
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