Lectures 1–4: Life, Evolution, & Selection
In certain coastal regions, individuals who carry one copy of the cystic fibrosis allele (CF) appear to have increased resistance to cholera, a severe diarrheal disease. Those with two normal alleles are more vulnerable to infection, while those with two CF alleles develop cystic fibrosis, a life-threatening genetic disorder.
Which type of natural selection does this scenario best represent?
A. Directional selection
B. Stabilizing selection
C. Heterozygote advantage
D. Disruptive selection
C. Heterozygote advantage
A diploid human skin cell has 46 chromosomes.
How many chromosomes will be in each daughter cell after mitosis?
How many chromosomes will be in each gamete after meiosis?
What is the benefit of independent assortment in meiosis?
46 chromosomes (identical diploid cells from mitosis) 2N -> 2N (two)
23 chromosomes (haploid gametes from meiosis) 2N -> 1N (four)
It increases genetic diversity by randomly distributing maternal and paternal chromosomes into gametes.
In a newly discovered single-celled eukaryote, researchers observe an organelle that produces methane and has DNA highly similar to that of certain archaea. This organelle also divides independently from the rest of the cell.
What does this discovery most likely support?
A. The theory of abiogenesis
B. The role of cyanobacteria in oxygen production
C. The concept of ecological succession
D. The endosymbiotic origin of specialized organelles
D. The endosymbiotic origin of specialized organelles
A plant species in a sunny, dry environment shows thick waxy leaves, deep roots, and produces seeds that are carried by wind. Which combination of adaptations does this plant most likely represent?
A. Aquatic plant adaptations
B. Land plant adaptations to light stress and water loss
C. Fungal mutualism with decomposers
D. A plant lacking chloroplasts and pigments
B. Land plant adaptations to light stress and water loss
Which process occurs when a gene in DNA is copied into mRNA?
A. Replication
B. Transcription
C. Translation
D. Transgenesis
B. Transcription
Which of the following best illustrates a tradeoff caused by human bipedalism and how natural selection acted on genetic diversity to address it?
A. The human pelvis widened to allow upright walking, resulting in easier childbirth.
B. A narrowed pelvis for bipedalism made childbirth more difficult, leading to earlier birth and longer brain development outside the womb.
C. Bipedalism allowed humans to develop darker skin as a protective barrier.
D. Folate breakdown due to UV radiation caused human pelvis shapes to change.
B. A narrowed pelvis for bipedalism made childbirth more difficult, leading to earlier birth and longer brain development outside the womb.
What structure in the human cell cycle is responsible for halting division if DNA damage is detected?
A. Ribosome
B. Centrosome
C. p53
D. Actin
C. p53
Which term describes when one species benefits and the other is unaffected?
A. Parasitism
B. Commensalism
C. Mutualism
D. Competition
B. Commensalism
A small bird picks insects off the back of a buffalo. The bird gets food, and the buffalo gets rid of pests.
What type of relationship is this?
A. Parasitism
B. Mutualism
C. Commensalism
D. Competition
B. Mutualism
A medical researcher thinks a new drug might reduce anxiety in mice. She gives one group of mice the drug and another group a placebo, then measures how much time each group spends exploring an open field.
What is the hypothesis in this scenario?
A. Mice are mammals that can experience anxiety.
B. The new drug will reduce anxiety-related behaviors in mice.
C. Measuring time in the open field can show anxiety levels.
D. Placebos have no effect on anxiety.
B. The new drug will reduce anxiety-related behaviors in mice.
During a period of significant climate change in early hominin habitats, individuals who were more behaviorally flexible and had slightly larger brains were more likely to survive and reproduce.
Which evolutionary concept does this best illustrate?
A. Directional selection
B. Variability selection hypothesis
C. Stabilizing selection
D. Convergent evolution
B. Variability selection hypothesis
Which process leads to the production of 4 haploid gametes?
A. Mitosis
B. Meiosis
C. Binary fission
D. Cytokinesis
B. Meiosis
What is biodiversity's role in ecosystem health?
A. Decreases nutrient availability
B. Promotes instability
C. Increases resilience and function
D. Reduces productivity
C. Increases resilience and function
A species of fast-growing freshwater snail is introduced to a lake. It eats a wide range of plants, reproduces quickly, and has no predators in the area. After one year, native species begin to decline.
What is the best classification of this species and one reason for its success?
A. Native species; it balances the food web
B. Introduced species; it has a specialized diet
C. Invasive species; it reproduces rapidly and has no natural predators
D. Commensal species; it benefits the native plants
C. Invasive species; it reproduces rapidly and has no natural predators
Which structure insulates the axon and speeds up signal transmission?
A. Dendrite
B. Soma
C. Axon terminal
D. Myelin sheath
D. Myelin sheath
The Namib desert beetle collects drinking water from fog using bumps on its back that attract water droplets, which then slide into its mouth. Engineers studying this beetle have designed fog-catching nets and self-filling water bottles for use in arid regions. At the same time, certain desert plants have evolved similar surface structures to harvest water from air.
Which two concepts are best illustrated by these examples?
A. Artificial selection and migration
B. Genetic bottleneck and mutation
C. Convergent evolution and biomimicry
D. Speciation and coevolution
C. Convergent evolution and biomimicry
What evolutionary trait is linked to narrowed human pelvises and early childbirth?
A. Bipedalism
B. Tool use
C. Opposable thumbs
D. Thermoregulation
A. Bipedalism
The Namib desert beetle collects drinking water from fog using bumps on its back that attract water droplets, which then slide into its mouth. Engineers studying this beetle have designed fog-catching nets and self-filling water bottles for use in arid regions. At the same time, certain desert plants have evolved similar surface structures to harvest water from air.
Which two concepts are best illustrated by these examples?
A. Artificial selection and migration
B. Genetic bottleneck and mutation
C. Convergent evolution and biomimicry
D. Speciation and coevolution
C. Convergent evolution and biomimicry
Fertilizer runoff from farms leads to massive algal blooms in nearby lakes. After the algae die, decomposing bacteria use up the oxygen in the water, killing fish and aquatic organisms.
What is the term for this low-oxygen condition, and what human action contributes to it?
A. Ocean acidification; overfishing
B. Dead zone; excessive fertilizer use
C. Eutrophication; plastic pollution
D. Hypoxia; carbon dioxide emissions
B. Dead zone; excessive fertilizer use
What is the role of neurotransmitters in the nervous system?
A. Speed up blood flow
B. Transmit electrical signals
C. Store energy
D. Transmit chemical signals across synapses
D. Transmit chemical signals across synapses
What does the scientific method begin with?
A. Drawing conclusions
B. Performing an experiment
C. Making an observation
D. Forming a theory
C. Making an observation
Which term refers to cells with two sets of chromosomes?
A. Haploid
B. Diploid
C. Polyploid
D. Aneuploid
B. Diploid
In a species of birds, males display elaborate courtship dances with bright feathers to attract females. Meanwhile, males of a related species compete directly by fighting for control of nest sites that females need to lay eggs.
Which types of sexual selection are illustrated in these two bird species?
A. Both are examples of intrasexual selection
B. Both are examples of intersexual selection
C. The first is intersexual; the second is intrasexual
D. The first is intrasexual; the second is intersexual
C. The first is intersexual; the second is intrasexual
In a DNA strand, the base cytosine (C) will always pair with:
A. Adenine
B. Guanine
C. Thymine
D. Uracil
B. Guanine
A parasite infects a species of ant and alters its behavior so that the ant climbs to the top of a blade of grass and clamps its jaws shut until it's eaten by a grazing animal.
What concepts are best illustrated by this scenario?
A. Low virulence and direct transmission
B. High virulence and waterborne transmission
C. Parasitism and host manipulation to enhance transmission
D. Vector-borne transmission and intersexual selection
C. Parasitism and host manipulation to enhance transmission