Question 1

Which of the following best explains why meiosis, but not mitosis, leads to increased genetic variation in sexually reproducing organisms?

Accepted Answer

Meiosis includes processes such as independent assortment and crossing over, which shuffle genetic material.

Question 2

A patient is diagnosed with a tumor that does not invade surrounding tissues and does not spread to other parts of the body. Which term best describes this tumor?

Accepted Answer

Benign

Question 3

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

Accepted Answer

S phase; each chromosome is duplicated to form sister chromatids.

Question 4

A cell with a diploid number of 8 ($$2n = 8) $$undergoes mitosis. How many chromosomes will each daughter cell have after division?

Accepted Answer

$$8$$

Question 5

Which of the following scenarios best illustrates Mendel’s Law of Segregation?

Accepted Answer

A plant with genotype $$Aa$$ produces gametes with either $$A or$$ $$a$$ alleles, but not both.

Question 6

A woman who is heterozygous for a recessive genetic disorder ($$Dd) $$and a man who is homozygous dominant ($$DD) $$have a child. What is the probability that their child will be a carrier of the disorder?

Accepted Answer

$$50\%$$

Question 7

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

Accepted Answer

DNA contains thymine, while RNA contains uracil.

Question 8

A mutation changes the DNA sequence from $$	ext{ATG CCA TGA} to$$ $$	ext{ATG CCA TAA}. $$What type of mutation is this, and what is its likely effect?

Accepted Answer

Substitution; may result in a premature stop codon.

Question 9

Which of the following best explains why nondisjunction during meiosis can lead to Down syndrome?

Accepted Answer

Nondisjunction results in gametes with an abnormal number of chromosomes, such as three copies of chromosome 21.

Question 10

In a dihybrid cross between two heterozygous pea plants ($$RrYy 	imes RrYy$$), what is the expected phenotypic ratio among the offspring, according to Mendel’s Law of Independent Assortment?

Accepted Answer

$$9:3:3:1$$

Question 11

Which of the following events occurs during anaphase of mitosis?

Accepted Answer

Sister chromatids are pulled apart toward opposite poles.

Question 12

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 for this trait?

Accepted Answer

Autosomal dominant

Question 13

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

Accepted Answer

tRNA carries amino acids to the ribosome and matches them to the mRNA codons.

Question 14

A cell loses control of its cell cycle checkpoints and begins to divide uncontrollably. Which of the following is the most likely consequence?

Accepted Answer

The cell may form a tumor, potentially leading to cancer.

Question 15

Which of the following is an example of codominance in human genetics?

Accepted Answer

A person with type AB blood expresses both A and B antigens equally.

Question 16

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 17

A geneticist is studying a trait controlled by multiple genes, each contributing a small effect to the phenotype. Which inheritance pattern does this describe?

Accepted Answer

Polygenic inheritance

Question 18

Which of the following statements about crossing over is correct?

Accepted Answer

Crossing over occurs during prophase I of meiosis and increases genetic diversity.

Question 19

A DNA strand has the sequence $$5'	ext{-ATCGGTA-}3'. $$What is the complementary RNA sequence produced during transcription?

Accepted Answer

$$5'	ext{-UAGCCAU-}3'$$

Question 20

A frameshift mutation is most likely to result from which of the following changes to a DNA sequence?

Accepted Answer

The insertion or deletion of a nucleotide

Cell Division, Genetics, and DNA: Study Guide for General Biology

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