Question 1

Which of the following best describes the difference between a genotype and a phenotype?

Accepted Answer

Genotype is the combination of alleles an organism carries, while phenotype is the physical expression of those alleles.

Question 2

A plant with genotype RrTt is crossed with a plant with genotype RRTT. R = red petals, r = white petals, T = tall, t = short. What is the expected phenotypic ratio among the offspring?

Accepted Answer

All offspring will be tall with red petals.

Question 3

If the DNA template strand is TCG, what is the corresponding mRNA codon produced during transcription?

Accepted Answer

$$	ext{AGC}$$

Question 4

Which of the following best describes the function of tRNA during translation?

Accepted Answer

tRNA brings specific amino acids to the ribosome by matching its anticodon to the mRNA codon.

Question 5

A point mutation changes the DNA template from TCG to ACG. What type of mutation is this, and what is the likely effect on the amino acid sequence?

Accepted Answer

It is a point mutation, which may result in a different amino acid being incorporated.

Question 6

Which of the following is true about codominance?

Accepted Answer

Both alleles are expressed equally in the phenotype.

Question 7

Which process is responsible for the synthesis of mRNA from a DNA template?

Accepted Answer

Transcription

Question 8

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 9

Which of the following best describes the role of perforin in the immune response?

Accepted Answer

Perforin is a protein released by cytotoxic T cells that creates pores in target cell membranes.

Question 10

Which of the following is a characteristic of an autoimmune disease?

Accepted Answer

The immune system attacks the body's own tissues.

Question 11

Which of the following best distinguishes between B lymphocytes and T lymphocytes?

Accepted Answer

B lymphocytes produce antibodies as part of humoral immunity, while T lymphocytes are involved in cell-mediated immunity.

Question 12

Which of the following is an example of a mutagen?

Accepted Answer

Ultraviolet (UV) radiation

Question 13

Which of the following best describes recombinant DNA (rDNA)?

Accepted Answer

DNA that is formed by combining DNA from two different sources.

Question 14

A test cross is used to determine the genotype of an individual with a dominant phenotype. Which of the following best describes how this is done?

Accepted Answer

Cross the individual with a homozygous recessive individual.

Question 15

Which of the following is a key difference between DNA and RNA?

Accepted Answer

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

Question 16

Which of the following best describes the process of clonal selection in the immune system?

Accepted Answer

A specific lymphocyte is activated and proliferates in response to an antigen.

Question 17

Which of the following is a likely consequence of a frameshift mutation in a gene coding for a protein?

Accepted Answer

The reading frame of the gene will be altered, potentially resulting in a nonfunctional protein.

Question 18

Which of the following best describes humoral immunity?

Accepted Answer

It involves the production of antibodies by B cells to neutralize pathogens.

Question 19

A patient is diagnosed with HIV. Which component of their immune system is most directly affected by the virus?

Accepted Answer

Helper T cells

Question 20

Which of the following best explains why gene therapy can be used to treat genetic diseases?

Accepted Answer

Gene therapy introduces a functional copy of a gene to replace a defective one.

Unit 4 Biology Study Guide: Genetics, Protein Synthesis, and Immunology

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