Biology

Molecular Biology and Genetics

717 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

How are base pairs of nucleotides held together?

  1. sugar phosphate backbone

  2. hydrogen bonds

  3. their complementary pairing

  4. ionic bonds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The two strands of the DNA double helix are held together by hydrogen bonds between the complementary nitrogenous bases.

Multiple choice

What makes up a nucleotide?

  1. phosphate group

  2. nitrogen base

  3. 5-carbon sugar

  4. All of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A nucleotide consists of three components: a phosphate group, a 5-carbon sugar (deoxyribose or ribose), and a nitrogenous base.

Multiple choice

Which of the nitrogenous bases are classified as purines?

  1. adenine and guanine

  2. adenine and thymine

  3. cytosine and guanine

  4. cytosine and thymine
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Purines are double-ring nitrogenous bases, which include adenine and guanine. Pyrimidines are single-ring bases, which include cytosine and thymine.

Multiple choice evs - i constituents of food dietary sources of proteins types of nutrients calorific value of nutrients

Which statement is correct for biomolecules

  1. DNA is a polymer of ribonucleotides

  2. All carbohydrates break down into glucose

  3. RNA is single stranded and contain different purine

    base than DNA

  4. Sequence of amino acids determine primary structure

    of proteins
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The shape, size, structure and biological functions of proteins are determined by the number, type and arrangement of amino acids.

Multiple choice biochemical polymers polymerisation chemistry

Nucleic acids are the polymers of __________

  1. nucleosides

  2. nucleotides

  3. bases

  4. sugars
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nucleic acids are made up of individual monomers called nucleotides

Multiple choice biochemical polymers polymerisation chemistry

Which of the following is correxect bonding in nucleotide?

  1. $A - T, \ G - C$
  2. $A - G,\ T - C$
  3. $G - T,\ A - C$
  4. $A - A,\ T - T$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The correct bonding pairs in Nucleotide are Adenine- Thymine, Guanine- Cytosine where Adenine, Thymine, Guanine, Cytosine are bases which form in pairs to build up Nucleotides.

Multiple choice biochemical polymers polymerisation chemistry

A unit in nucleic acid which contains 'base-sugar phosphate' unit is called ?

  1. nuleotide

  2. nucleoside

  3. phosphotide

  4. polypeptide
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Nucleotides are composed of three sub-unit molecules: a nitrogenous base, a five-carbon sugar (ribose or deoxyribose), and at least one phosphate group.
Multiple choice biochemical polymers polymerisation chemistry

Which of the following bases is not present in DNA?

  1. Adenine

  2. Thymine

  3. Cytosine

  4. Uracil
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
In DNA, four bases have been found. They are adenine (A), guanine (G), cytosine (C) and thymine (T).
Uracil is present in RNA.
Multiple choice biochemical polymers polymerisation chemistry

The $AT/GC$ ratio in human beings is: (where $A=$adenine,$T=$thymine,$G=$Guanine,$C=$cytosine)

  1. $1$
  2. $1.52$
  3. $9.3$
  4. $2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A-T/G-C ratio is human beings is equal to 1.52

where A=Adenine T-Thymine, G-Guanine, C-Cytosine

Multiple choice biochemical polymers polymerisation chemistry

A nucleotide consists of

  1. carbon sugar

  2. nitrogen containing base

  3. phosphoric acid

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A nucleotide is made up of the following
Sugar ring, base (adenine, guanine, cytosine, thymine/uracil), phosphate molecule.
The sugar ring is made up of carbon atoms. The bases are nitrogenous. So, all of these are true.

Multiple choice biochemical polymers polymerisation chemistry

Which among the following sequence defines Ribonucleotide?

  1. Ribose sugar $+$ Nitrogenous base
  2. Ribose sugar $+$ Protein
  3. Ribose sugar $+$ Phosphoric acid
  4. Ribonucleoside $+$ Phosphate group
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice biochemical polymers polymerisation chemistry

A nucleotide is made up of:

  1. a base and sugar

  2. a base and phosphate unit

  3. a sugar and phosphate unit

  4. a sugar, a base and a phosphate unit
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sugar + Base + a phosphate unit constitute one nucleotide.
This is the definition of a nucleotide.