Question 1

Which of the following best explains why males are more likely than females to express recessive X-linked genetic disorders, such as hemophilia?

Accepted Answer

Males have only one X chromosome, so a single recessive allele will be expressed.

Question 2

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

Accepted Answer

$$\frac{1}{2}$$

Question 3

Which chromosomal mutation is most likely to result in a gene being present in two copies on the same chromosome, potentially leading to overexpression?

Accepted Answer

Duplication

Question 4

During DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

Ligase

Question 5

A scientist observes that after several rounds of DNA replication, each DNA molecule consists of one old and one new strand. Which model of replication does this observation support?

Accepted Answer

Semi-conservative replication

Question 6

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Question 7

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 8

Which process occurs in the nucleus and results in the production of a complementary RNA strand from a DNA template?

Accepted Answer

Transcription

Question 9

Which of the following modifications is added to the 5’ end of a eukaryotic mRNA during processing?

Accepted Answer

5’ cap

Question 10

Which of the following is NOT evidence supporting Darwin’s theory of evolution by natural selection?

Accepted Answer

Perfect adaptation of all organisms to their environment

Question 11

A population of beetles is exposed to a pesticide. Over several generations, most beetles are resistant to the pesticide. Which type of selection is most likely occurring?

Accepted Answer

Directional selection

Question 12

Which equation represents the Hardy-Weinberg equilibrium for allele and genotype frequencies in a population?

Accepted Answer

$$p^2 + 2pq$$ + $$q^2 = 1$

Question 13

Which of the following is NOT a condition required for Hardy-Weinberg equilibrium?

Accepted Answer

Small population size

Question 14

A small group of finches colonizes a new island, and their allele frequencies differ from the original population. This is an example of:

Accepted Answer

Founder effect

Question 15

Which of the following best describes the role of telomeres in eukaryotic chromosomes?

Accepted Answer

They protect chromosome ends from degradation.

Question 16

A patient’s karyotype shows a segment of chromosome 5 attached to chromosome 15. This is an example of which chromosomal mutation?

Accepted Answer

Translocation

Question 17

Which of the following best explains why a Barr body is found in the nuclei of female mammals but not males?

Accepted Answer

Females have two X chromosomes, and one is inactivated as a Barr body.

Question 18

Which of the following scenarios best illustrates gene flow?

Accepted Answer

Individuals from one population migrate and breed with another population, introducing new alleles.

Question 19

Which of the following is the correct sequence of events in the central dogma of molecular biology?

Accepted Answer

DNA → RNA → Protein

Question 20

A mutation causes a shift in the reading frame of the genetic code. What type of mutation is this?

Accepted Answer

Frameshift mutation

Chromosomal Inheritance, DNA Replication, Gene Expression, and Evolution: Study Notes

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