Question 1

Which of the following best explains how alternative splicing increases protein diversity in eukaryotic cells?

Accepted Answer

By allowing different combinations of exons to be joined together, producing multiple mRNA transcripts from a single gene.

Question 2

A mutation changes a codon from $$\mathrm{GAG} ($$glutamic acid) to $$\mathrm{GUG} ($$valine) in the hemoglobin gene. What type of mutation is this, and what is a likely consequence?

Accepted Answer

Missense mutation; it may alter the protein's function, as seen in sickle cell anemia.

Question 3

During meiosis, homologous chromosomes fail to separate during anaphase I. What is the most likely result in the gametes produced?

Accepted Answer

Some gametes will have an extra chromosome (n+1), and some will have one less (n-1), leading to aneuploidy.

Question 4

Which of the following statements about the Central Dogma of molecular biology is correct?

Accepted Answer

DNA is transcribed into mRNA, which is then translated into protein.

Question 5

Which of the following best describes the difference between a gene and an allele?

Accepted Answer

A gene is a region of DNA that codes for a protein, while an allele is a variant form of that gene.

Question 6

Which of the following is a key difference between mitosis and meiosis?

Accepted Answer

Mitosis produces two genetically identical diploid cells, while meiosis produces four genetically diverse haploid cells.

Question 7

A point mutation in a gene does not change the amino acid sequence of the resulting protein. What is this type of mutation called, and why does it occur?

Accepted Answer

Silent mutation; due to the redundancy of the genetic code.

Question 8

Which experimental result from the Miller-Urey experiment provided evidence for the chemical evolution of life?

Accepted Answer

The formation of amino acids such as glycine from simple gases and electrical energy.

Question 9

Which of the following best explains why sexual reproduction can be advantageous in changing environments?

Accepted Answer

It increases genetic variation through recombination and independent assortment, allowing populations to adapt more rapidly.

Question 10

Which of the following is true regarding the structure of DNA as described by Watson and Crick?

Accepted Answer

DNA consists of two antiparallel strands forming a double helix, with complementary base pairing between purines and pyrimidines.

Question 11

A cell is observed to have 46 chromosomes at the start of mitosis. After mitosis and cytokinesis, how many chromosomes will each daughter cell have?

Accepted Answer

46 chromosomes

Question 12

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

Accepted Answer

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

Question 13

Which of the following chromosomal rearrangements is most likely to result in a gene dosage imbalance and potentially severe phenotypic effects?

Accepted Answer

Duplication

Question 14

A diploid organism has a genotype Aa for a particular gene. Which of the following statements is correct?

Accepted Answer

The organism is heterozygous at that gene locus.

Question 15

Which of the following best explains why a frameshift mutation is often more severe than a point mutation?

Accepted Answer

A frameshift changes the reading frame, altering every amino acid downstream of the mutation.

Question 16

Which of the following is a direct result of independent assortment during meiosis?

Accepted Answer

Gametes with different combinations of maternal and paternal chromosomes.

Question 17

Which of the following is NOT a function of DNA in living organisms?

Accepted Answer

Catalyzing metabolic reactions as an enzyme.

Question 18

Which of the following best describes the evolutionary significance of mutations?

Accepted Answer

They introduce new genetic variation into populations, which can be acted upon by natural selection.

Question 19

Which of the following best explains why the number of genes does not directly correlate with organismal complexity?

Accepted Answer

Alternative splicing and differential gene expression allow for greater protein diversity from a limited number of genes.

Genetic Variation, DNA Structure, and the Molecular Basis of Inheritance

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