Question 1

Which of the following best explains why single-celled organisms undergo cell division?

Accepted Answer

To reproduce and ensure survival of the species via mitosis

Question 2

During which phase of the cell cycle do chromosomes become most condensed and visible under a light microscope, and why is this important?

Accepted Answer

M phase; to facilitate accurate segregation of chromosomes

Question 3

Which of the following correctly describes the relationship between DNA, genes, and chromosomes?

Accepted Answer

A chromosome is composed of DNA and proteins, and contains many genes

Question 4

Which of the following best describes the role of histones in eukaryotic cells?

Accepted Answer

They regulate gene expression and package DNA into chromatin

Question 5

A human somatic cell contains 46 chromosomes. After mitosis and cytokinesis, how many chromosomes will each daughter cell contain, and what is their ploidy?

Accepted Answer

46 chromosomes, diploid

Question 6

Which process is responsible for the genetic variation observed in offspring produced by sexual reproduction, and when does it occur?

Accepted Answer

Crossing over during prophase I of meiosis

Question 7

A pea plant with genotype $$Yy ($$yellow seeds) is crossed with a $$yy ($$green seeds) plant. According to Mendel's law of segregation, what is the expected phenotypic ratio in the offspring?

Accepted Answer

1 yellow : 1 green

Question 8

In a dihybrid cross between two heterozygous pea plants ($$YyRr 	imes YyRr$$), what is the expected phenotypic ratio in the F2 generation according to the law of independent assortment?

Accepted Answer

9:3:3:1

Question 9

Which of the following statements about the semiconservative model of DNA replication is correct?

Accepted Answer

Each new DNA molecule consists of one parental and one new strand

Question 10

Which enzyme is responsible for synthesizing the new DNA strand during replication, and in which direction does it synthesize?

Accepted Answer

DNA polymerase; 5' to 3'

Question 11

Why is a primer required for DNA synthesis, and what is it made of?

Accepted Answer

It provides a 3' hydroxyl group for DNA polymerase; made of RNA

Question 12

Which of the following best describes the difference between leading and lagging strand synthesis during DNA replication?

Accepted Answer

Leading strand is synthesized continuously, lagging strand is synthesized in Okazaki fragments

Question 13

Which of the following codons has a dual function in translation, and what are its roles?

Accepted Answer

$$AUG$$; start codon and codes for methionine

Question 14

A woman with blood type $$AB$$ and a man with blood type $$O$$ have children. Which blood types are possible for their offspring?

Accepted Answer

A and B only

Question 15

Which of the following best explains why two genes are considered 'linked'?

Accepted Answer

They are located on the same chromosome and tend to be inherited together

Question 16

In a testcross between a dihybrid ($$YyRr) $$and a double recessive ($$yyrr$$), what phenotypic ratio is expected if the genes are unlinked?

Accepted Answer

1:1:1:1

Question 17

Which of the following is NOT a reason why the complete nucleotide sequence of a eukaryotic protein-coding gene cannot be deduced from the polypeptide sequence it encodes?

Accepted Answer

The sequence of the polypeptide determines the sequence of the gene

Question 18

Which of the following statements about tRNAs is correct?

Accepted Answer

tRNAs carry amino acids to the ribosome and have anticodons that pair with mRNA codons

Question 19

Which enzyme is responsible for attaching the correct amino acid to its corresponding tRNA, and how many types of this enzyme exist in cells?

Accepted Answer

Aminoacyl-tRNA synthetase; 20 types

Question 20

Which of the following best describes the chromosome theory of inheritance?

Accepted Answer

Genes are located on chromosomes, which segregate and independently assort during meiosis

Comprehensive Study Guidance for Cell Division, Genetics, and Molecular Biology

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