Question 1

A plant with genotype $$Tt ($$where $$T is $$dominant for tall and $$t is $$recessive for short) is crossed with another plant with genotype $$Tt. $$What is the expected phenotypic ratio of their offspring?

Accepted Answer

3 tall : 1 short

Question 2

Which of the following best describes the law of independent assortment?

Accepted Answer

Each pair of alleles segregates independently of other pairs during gamete formation.

Question 3

A woman who is a carrier for an X-linked recessive disorder (genotype $$X^N X^n) $$and a man who is unaffected ($$X^N Y) $$have a son. What is the probability that their son will have the disorder?

Accepted Answer

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

Question 4

Which of the following scenarios is an example of incomplete dominance?

Accepted Answer

A red-flowered plant crossed with a white-flowered plant produces pink-flowered offspring.

Question 5

Which chromosomal abnormality results from the failure of homologous chromosomes to separate during meiosis?

Accepted Answer

Nondisjunction

Question 6

A person with Down syndrome has three copies of chromosome 21. This condition is best described as:

Accepted Answer

Trisomic

Question 7

Which of the following best describes the semiconservative model of DNA replication?

Accepted Answer

Each new DNA molecule consists of one old strand and one new strand.

Question 8

During DNA replication, which enzyme is responsible for adding nucleotides to the growing DNA strand?

Accepted Answer

DNA polymerase

Question 9

Which of the following statements about telomeres is correct?

Accepted Answer

Telomeres are repetitive DNA sequences at the ends of chromosomes that protect them from degradation.

Question 10

Which process involves the synthesis of an RNA molecule from a DNA template?

Accepted Answer

Transcription

Question 11

A mutation changes the codon $$UAC ($$which codes for tyrosine) to $$UAA (a $$stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 12

Which of the following best describes an operon?

Accepted Answer

A cluster of genes under the control of a single promoter and operator.

Question 13

Which of the following is true about histone acetylation?

Accepted Answer

It relaxes chromatin structure, promoting gene expression.

Question 14

A repressible operon is typically:

Accepted Answer

Turned on unless a corepressor is present.

Question 15

Which of the following best describes a frameshift mutation?

Accepted Answer

A mutation that results from the insertion or deletion of nucleotides not in multiples of three, altering the reading frame.

Question 16

Which of the following is a function of non-coding RNA?

Accepted Answer

Regulating gene expression at the transcriptional and post-transcriptional level.

Question 17

A point mutation in a gene changes the codon $$GAA ($$glutamic acid) to $$GAG ($$also glutamic acid). What type of mutation is this?

Accepted Answer

Silent mutation

Question 18

Which of the following best explains why DNA methylation is important in eukaryotic cells?

Accepted Answer

It is involved in the regulation of gene expression by silencing genes.

Question 19

A child is born with a deletion of a segment of chromosome 5, resulting in a genetic disorder. Which type of chromosomal alteration does this represent?

Accepted Answer

Deletion

Question 20

During translation, which molecule brings amino acids to the ribosome?

Accepted Answer

tRNA

Genetics and Molecular Biology: Key Concepts for Final Exam

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