exam 3 asu bio 182 Questions And Answers Graded A

exam 3 asu bio 182 Questions And Answers Graded A
 Course
 BIO 182

Question 1:

Which of the following processes directly contributes to genetic variation in
populations?

 A) Mitosis
 B) Binary fission
 C) Independent assortment
 D) Apoptosis

Answer: C) Independent assortment
Rationale: Independent assortment during meiosis allows chromosomes to segregate
randomly, leading to genetic variation among gametes. Mitosis and binary fission produce
identical cells, and apoptosis is programmed cell death.



Question 2:

What is the primary role of DNA polymerase in DNA replication?

 A) Unwind the DNA double helix
 B) Join Okazaki fragments
 C) Add nucleotides to a growing DNA strand
 D) Seal gaps between DNA fragments

Answer: C) Add nucleotides to a growing DNA strand
Rationale: DNA polymerase is the enzyme responsible for adding nucleotides to the 3' end
of a growing DNA strand, ensuring accurate DNA replication. Other enzymes, like helicase
and ligase, assist with unwinding and joining fragments.



Question 3:

In natural selection, the survival and reproductive success of an individual is
determined by:

 A) Random chance
 B) Genetic drift
 C) Selective pressures
 D) Mutation rate

,Answer: C) Selective pressures
Rationale: Natural selection depends on selective pressures in the environment, such as
predators, climate, and competition, which favor organisms with advantageous traits.



Question 4:

Which of the following best describes a keystone species?

 A) A species that is the most numerous in a community
 B) A species that has a disproportionate impact on its environment
 C) A species with the highest reproductive rate
 D) A species that preys on other species in its community

Answer: B) A species that has a disproportionate impact on its environment
Rationale: Keystone species play a critical role in maintaining the structure of an ecological
community. Their removal leads to significant changes, often decreasing biodiversity.



Question 5:

In the Calvin cycle, carbon fixation initially produces a 3-carbon molecule known as:

 A) Pyruvate
 B) Glyceraldehyde-3-phosphate (G3P)
 C) Phosphoglycerate (PGA)
 D) RuBP

Answer: C) Phosphoglycerate (PGA)
Rationale: During carbon fixation, CO₂ is attached to RuBP, producing a short-lived 6-
carbon intermediate that splits into two molecules of 3-phosphoglycerate (PGA).



Question 6:

Genetic drift is most likely to affect which type of population?

 A) Large populations with high genetic diversity
 B) Small populations with low genetic diversity
 C) Populations undergoing gene flow
 D) Populations with selective mating

Answer: B) Small populations with low genetic diversity
Rationale: Genetic drift has a stronger effect in small populations due to the random
fluctuation of allele frequencies, which can lead to significant changes in genetic composition
over time.

,Question 7:

Which of the following is NOT a form of symbiosis?

 A) Parasitism
 B) Predation
 C) Mutualism
 D) Commensalism

Answer: B) Predation
Rationale: Symbiosis refers to close, long-term interactions between species. Predation is not
considered symbiosis because it involves a predator killing prey rather than a prolonged
interaction.



Question 8:

The movement of alleles between populations through migration is known as:

 A) Genetic drift
 B) Gene flow
 C) Natural selection
 D) Mutation

Answer: B) Gene flow
Rationale: Gene flow is the transfer of alleles between populations, which occurs when
individuals migrate, introducing new genetic material into a population and potentially
changing allele frequencies.



Question 9:

Which structure is directly involved in translation in the cytoplasm?

 A) Mitochondria
 B) Nucleus
 C) Ribosome
 D) Golgi apparatus

Answer: C) Ribosome
Rationale: The ribosome facilitates translation by reading mRNA and synthesizing proteins
based on the encoded genetic information. Other cell structures are involved in different
cellular functions.

, Question 10:

What type of selection favors individuals at both extremes of a trait distribution?

 A) Directional selection
 B) Stabilizing selection
 C) Disruptive selection
 D) Balancing selection

Answer: C) Disruptive selection
Rationale: Disruptive selection occurs when extreme phenotypes are favored over
intermediate ones, which can lead to a bimodal distribution of traits in a population.

Question 11:

In meiosis, crossing over occurs during which phase?

 A) Prophase I
 B) Metaphase I
 C) Anaphase II
 D) Telophase I

Answer: A) Prophase I
Rationale: Crossing over, where homologous chromosomes exchange genetic material,
occurs during Prophase I of meiosis. This process increases genetic diversity in gametes.



Question 12:

Which term describes a relationship where one organism benefits and the other is
unaffected?

 A) Mutualism
 B) Parasitism
 C) Commensalism
 D) Predation

Answer: C) Commensalism
Rationale: In commensalism, one organism benefits without harming or helping the other.
For example, barnacles on whales gain mobility without affecting the whale.



Question 13:

What is the main function of chloroplasts in plant cells?

 A) ATP production through cellular respiration