Q: In a population, the frequency of allele $$A is$$ $$0.7$$ and allele $$a is$$ $$0.3. $$According to Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes ($$Aa$$)?

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

Question 1

Which of the following best describes the difference between DNA replication and gene expression in eukaryotic cells?

Accepted Answer

DNA replication occurs only during the S phase of the cell cycle, while gene expression can occur throughout the cell cycle.

Question 2

A mutation changes a codon from $$	ext{GAA} to$$ $$	ext{GAG}$$, both of which code for glutamic acid. What type of mutation is this, and what is its likely effect?

Accepted Answer

It is a silent mutation and likely has no effect on the protein.

Question 3

Which of the following best explains why a protein destined for secretion is synthesized differently than a cytoplasmic protein?

Accepted Answer

The mRNA for secreted proteins is translated by ribosomes bound to the rough endoplasmic reticulum, while cytoplasmic proteins are translated by free ribosomes.

Question 4

A woman who is heterozygous for a recessive X-linked disorder has children with a man who does not have the disorder. What is the probability that their son will have the disorder?

Accepted Answer

$$50\%$$

Question 5

Which of the following is NOT a requirement for a population to be in Hardy-Weinberg equilibrium?

Accepted Answer

Non-random mating

Question 6

In a population, the frequency of allele $$A is$$ $$0.7$$ and allele $$a is$$ $$0.3. $$According to Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes ($$Aa$$)?

Accepted Answer

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

Question 7

Which of the following best describes the process of gene cloning?

Accepted Answer

Chop the gene, amplify it, insert it into a vector, grow host cells, and identify those with the gene.

Question 8

Which of the following is an example of incomplete dominance?

Accepted Answer

A cross between red-flowered and white-flowered snapdragons produces pink-flowered offspring.

Question 9

Which mechanism of microevolution involves the random change in allele frequencies due to chance events, especially in small populations?

Accepted Answer

Genetic drift

Question 10

Which of the following statements about CRISPR technology is correct?

Accepted Answer

It allows for precise editing of specific DNA sequences in living organisms.

Question 11

A pedigree shows a trait that appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 12

Which of the following is a postzygotic reproductive barrier according to the biological species concept?

Accepted Answer

Hybrid offspring are sterile.

Question 13

Which of the following best describes adaptive radiation?

Accepted Answer

A single ancestral species rapidly diversifies into many new species, often following colonization of new habitats or mass extinction events.

Question 14

Which of the following is NOT a type of point mutation?

Accepted Answer

Duplication

Question 15

Which of the following best explains why prokaryotes can regulate gene expression more rapidly than eukaryotes?

Accepted Answer

Transcription and translation are coupled in prokaryotes, allowing immediate protein synthesis.

Question 16

Which of the following is an example of artificial selection?

Accepted Answer

Humans breeding dogs for specific traits such as size or coat color.

Question 17

Which of the following best describes a transgenic organism?

Accepted Answer

An organism that contains a gene from another species.

Question 18

Which of the following is a correct statement about epigenetic inheritance?

Accepted Answer

It involves heritable changes in gene expression that do not alter the DNA sequence.

Question 19

Which of the following is a correct interpretation of a phylogenetic tree?

Accepted Answer

Species that share a more recent common ancestor are more closely related.

Question 20

Which of the following is a mechanism by which sympatric speciation can occur?

Accepted Answer

Polyploidy in plants leading to reproductive isolation within the same geographic area.

Unit 3 Study Guide: Genetics, Molecular Biology, and Evolution

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