Q: A population is in Hardy–Weinberg equilibrium with $$p = 0.7$$ and $$q = 0.3. $$What is the expected frequency of heterozygotes ($$Aa) in $$the next generation?

$$2pq = 2 \times 0.7 \times 0.3 = 0.42$$

Question 1

A population of beetles is isolated on an island. Over several generations, the frequency of allele A increases from $$p = 0.4 to$$ $$p = 0.9$$ without any evidence of migration, mutation, or selection. Which evolutionary force most likely caused this change, and why is this force especially strong in small populations?

Accepted Answer

Genetic drift; because random sampling effects are stronger when population size is small

Question 2

A scientist observes that in a population of 1000 plants, the genotype frequencies are $$AA = 0.36$$, $$Aa = 0.48$$, and $$aa = 0.16. If$$ $$p is $$the frequency of allele $$A$$ and $$q is $$the frequency of allele $$a$$, which equation correctly describes their relationship under Hardy–Weinberg equilibrium?

Accepted Answer

$$p + q = 1$$

Question 3

In a population genetics simulation, you observe that allele frequencies in several replicate populations diverge widely over time, with some populations losing allele $$A$$ entirely and others fixing it. What does this pattern indicate about the evolutionary process at work?

Accepted Answer

Genetic drift is causing random changes in allele frequency

Question 4

A population is in Hardy–Weinberg equilibrium with $$p = 0.7$$ and $$q = 0.3. $$What is the expected frequency of heterozygotes ($$Aa) in $$the next generation?

Accepted Answer

$$2pq = 2 	imes 0.7 	imes 0.3 = 0.42$$

Question 5

A population of fish is exposed to a pollutant that kills individuals with genotype $$aa. $$Over time, what will happen to the frequency of allele $$a$$ and why?

Accepted Answer

Allele $$a$$ will decrease due to natural selection against $$aa$$

Question 6

A dialysis tubing bag containing starch and glucose is placed in a beaker of I$$_2KI $$solution. After one hour, the solution inside the bag turns blue-black, and the solution outside tests positive for glucose but not starch. What can you conclude about the permeability of the membrane?

Accepted Answer

Only glucose and I$$_2KI $$can cross the membrane; starch cannot

Question 7

A red blood cell is placed in a solution and begins to swell until it bursts. Which of the following best describes the tonicity of the solution and the direction of water movement?

Accepted Answer

The solution is hypotonic; water moves into the cell

Question 8

A plant cell is placed in a solution and its plasma membrane pulls away from the cell wall. What is the name of this process, and what does it indicate about the solution's tonicity?

Accepted Answer

Plasmolysis; the solution is hypertonic

Question 9

Which of the following best describes the movement of water during osmosis?

Accepted Answer

Water moves from low solute concentration to high solute concentration

Question 10

A student observes onion root tip cells under a microscope. In one cell, chromosomes are aligned at the center of the cell, each attached to spindle fibers from both poles. Which stage of mitosis is this?

Accepted Answer

Metaphase

Question 11

During which phase of the cell cycle does DNA replication occur, and what is the result for the chromosomes?

Accepted Answer

S phase; each chromosome consists of two sister chromatids

Question 12

A human somatic cell (2n = 46) undergoes mitosis and cytokinesis. How many chromosomes will each daughter cell have, and how does this compare to the parent cell?

Accepted Answer

46 chromosomes; identical to the parent cell

Question 13

In a population, the frequency of allele $$A is$$ $$p = 0.8$$ and allele $$a is$$ $$q = 0.2. If $$random mating occurs and no evolutionary forces act, what will be the frequency of genotype $$aa in $$the next generation?

Accepted Answer

$$q^2 = 0.04$

Question 14

A population is exposed to both strong directional selection for allele $$A$$ and a low but constant mutation rate converting $$A to$$ $$a. $$What is the most likely long-term outcome for allele $$A$$?

Accepted Answer

Allele $$A$$ will increase but may not reach 100% due to mutation

Question 15

Which structure is responsible for attaching spindle fibers to chromosomes during mitosis, and why is this attachment important?

Accepted Answer

Kinetochore; it allows spindle fibers to pull chromatids apart

Question 16

A plant cell is placed in a hypotonic solution. What is the expected outcome, and why is this state ideal for plant cells?

Accepted Answer

The cell becomes turgid due to water entering the vacuole, providing structural support

Question 17

During the cytogenetics exercise, why are dividing white blood cells treated with a chemical that stops spindle formation before karyotyping?

Accepted Answer

To allow chromosomes to condense and be counted without separating

Question 18

Which of the following best explains why the root tip of an onion is an excellent location to observe mitosis under a microscope?

Accepted Answer

Root tip cells are actively dividing, making mitotic stages easy to find

Question 19

A student observes a cell with chromosomes decondensing, two nuclei forming, and a cell plate developing between them. Which stage is this, and what process is occurring?

Accepted Answer

Telophase and cytokinesis; the cell is completing division

Question 20

In the context of diffusion and osmosis, which of the following statements is correct regarding the movement of molecules across a selectively permeable membrane?

Accepted Answer

Osmosis is the movement of water from low to high solute concentration

BIO 102-03 Lab Exam 2 Study Guide: Population Genetics, Diffusion & Osmosis, and Mitosis

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