Biology

Molecular Biology and Genetics

985 Questions

Molecular biology and genetics explore the structure and function of DNA, RNA, genetic mutations, and heredity. Understanding these building blocks of life is essential for most biology examinations. Review these practice questions to test your molecular genetics knowledge.

DNA structure and basesGenetic mutationsNucleic acids compositionDNA sequencing and replication

Molecular Biology and Genetics Questions

Multiple choice

What percentage of Human Genome has been sequenced properly till date (2011)?

  1. 50%

  2. 60%

  3. 94%

  4. 84%
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As of 2011, approximately 94% of the human genome had been properly sequenced and assembled into high-quality finished sequence. This represented significant progress from earlier drafts, though some heterochromatic regions remained challenging to sequence completely.

Multiple choice

Nucleotides are building blocks of nucleic acids. Each nucleotide is a composite molecule formed by

  1. base-sugar-OH

  2. base-sugar-phosphate

  3. sugar-phosphate

  4. (base-sugar-phosphate)n
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 A nucleotide is one of the structural components or building blocks of DNA and RNA. A nucleotide consists of a base (one of four chemicals: adenine, thymine, guanine, and cytosine) plus a molecule of sugar and one of phosphoric acid.

Multiple choice

___________ carries all the information about the organism.

  1. Platelets

  2. WBC

  3. RBC

  4. DNA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA carries all the genetic information about an organism - it contains the complete blueprint for building and maintaining that organism. Blood cells (RBCs, WBCs, platelets) do not contain DNA or carry the organism's genetic information - RBCs lack nuclei entirely in mammals.

Multiple choice

Loss of a purine base to form an apurinic site results into

  1. spontaneous mutation by deamination

  2. spontaneous mutation by depurination

  3. induced mutation

  4. errors introduced during DNA repair
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Loss of a purine base (A or G) to form an apurinic site (AP site) is depurination, which results into spontaneous mutation. AP site has neither a purine nor a pyrimidine base, either spontaneously or due to DNA damage.

Multiple choice

What happens in a tautomeric shift?

  1. Adenine and guanine are changed and can no longer form base pairs.

  2. The purines chemically get mutated to pyrimidines.

  3. Hydrogen atoms move from one position to another position.

  4. Carbon atoms move to form a base with altered properties.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In tautomeric shift, hydrogen atoms move from one position in a purine or pyrimidine to another position; for example, from an amino group to a ring nitrogen.

Multiple choice

A mutation that causes a change in a single nucleotide in DNA

  1. causes the codon to be correct, but the anti-codon to be incorrect

  2. causes protein synthesis to stop

  3. changes the corresponding nucleotide in mRNA, resulting in a different codon

  4. will have no effect on the resulting protein
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A change in a single nucleotide in DNA changes the corresponding nucleotide in mRNA, resulting in a different codon that codes for a different amino acid.

Multiple choice

UV radiations induce mutation by

  1. inversion of base pairs

  2. formation of pyrimidine hydrates

  3. formation of thymine dimers

  4. deletion of a base pair
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

UV radiations induce mutation by formation of thymine dimer. Dimers ultimately perturb the DNA double helix and interfere with accurate DNA replication.

Multiple choice

Match the following:

 
Family
Genetic material
1. Hepadnaviridae a. Partly double-stranded DNA
2. Adenoviridae b. Double-stranded DNA
3. Parvoviridae c. Single-stranded DNA
4. Picornaviridae d. Positive single-stranded RNA
  1. 1. Hepadnaviridae d. Positive single-stranded RNA
    2. Adenoviridae c. Single-stranded DNA
    3. Parvoviridae b. Double-stranded DNA
    4. Picronaviridae a. Partly double-stranded DNA
  2. 1. Hepadnaviridae a. Partly double-stranded DNA
    2. Adenoviridae b. Double-stranded DNA
    3. Parvoviridae c. Single-stranded DNA
    4. Picronaviridae d. Positive single-stranded RNA
  3. 1. Hepadnaviridae b. Double-stranded DNA
    2. Adenoviridae c. Single-stranded DNA
    3. Parvoviridae d. Single-stranded positive RNA
    4. Picronaviridae a. Partly double-stranded DNA
  4. 1. Hepadnaviridae c. Single-stranded DNA
    2. Adenoviridae d. Positive single-stranded RNA
    3. Parvoviridae a. Partly double-stranded DNA
    4. Picronaviridae b. Double-stranded DNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is the correct match. There is one family of partly double-stranded DNA virus: Hepadnaviridae; There is one family of single-stranded DNA virus that infect humans: Parvoviridae; Adenoviridae is a double-stranded DNA virus; Picronaviridae is a positive single-stranded RNA virus.