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

What is the full form of DNA?

  1. Do Not Ask!

  2. Deoxyribonucleic acid

  3. Diochomonic acid

  4. Danny Newton Asher
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA stands for Deoxyribonucleic acid, which is the molecule that carries genetic instructions for the development and functioning of living organisms.

Multiple choice botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

Read (i) to (v) and find the correct option
(i) Nitrogen base is linked to pentose sugar through N-glycosidic linkage
(ii) Phosphate group is linked to 5 - OH of a nucleoside through phosphoester linkage
(iii) Two nucleosides are linked through 3' -5' N-glycosidic linkage
(iv) Negatively charged DNA is wrapped around positively charged histone octamer to form nucleosome
(v) Chromatin that is more densely packed and stains dark is called euchromatin

  1. i, ii, iii wrong

  2. iv alone is wrong

  3. iii and v are wrong

  4. i alone is wrong

  5. i, ii and iv are wrong
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Statement (iii) is wrong because nucleosides are linked by phosphodiester bonds, not N-glycosidic linkages. Statement (v) is wrong because densely packed chromatin is heterochromatin, not euchromatin.

Multiple choice biology inherited changes linkage and crossing over linkage and recombination genetics: inheritance

A DNA molecule measures 204 nm in length; 35% of the molecule has AT base pairs. Find out the number of H-bonds existing between the two strands of DNA.

  1. 1590

  2. 159

  3. 1410

  4. 141
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA length 204 nm = 600 base pairs (0.34 nm/bp). 35% AT = 210 AT pairs (2 H-bonds each = 420). 65% GC = 390 GC pairs (3 H-bonds each = 1170). Total = 420 + 1170 = 1590.

Multiple choice biology inherited changes linkage and crossing over linkage and recombination genetics: inheritance

Assume that the occurrence of nitrogen bases in adjacent positions in a DNA strand is random. Identify the minimum number of nucleotides in a DNA strand where GAAT can occur once on the basis of probability

  1. 512

  2. 256

  3. 4096

  4. 1024
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The probability of a specific 4-nucleotide sequence occurring at any position is (1/4)^4 = 1/256. To expect this sequence to occur once, you need 256 positions. Thus, 256 nucleotides are required.

Multiple choice polarisation of light polarisation wave optics optics physics

The helical structures of nucleic acids can be studied by using :

  1. Interference phenomenon

  2. Diffraction pattern

  3. Polarised light

  4. Photoelectric effect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Polarised light is used to studied helical structures of nucleic acids using different methods such as optical rotatory dispersion. In this method due to refractive indices of the medium for left and right circularly polarised light reflects the structural details of such molecular complexes.

Multiple choice polarisation of light polarisation wave optics optics physics

Consider the following statements A and B. Identify the correct statements.
(A) Polarized light can be used to study the helical structure of nucleic acids.
(B) Optical axis is a direction and not any particular line in the crystal.

  1. A and B are correct

  2. A and B are wrong

  3. A is correct and B is wrong

  4. A is wrong and B is correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nucleic acid is an optically active medium. When circularly polarized light passes through an absorbing optically active medium, the speeds between right and left polarizations differ as well as their wavelengths. This can be used to study the helical structure of nucleic acids.
An optical axis is a line along which there is some degree of rotational symmetry in an optical system. Thus it is a particular direction and not any
random line.

Multiple choice zoology respiration in organisms active transport and passive transport types of plant transport atp

In which molecule is energy stored in the body?

  1. RNA

  2. DNA

  3. ADP

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

Adenosine triphosphate is a nucleotide also known as the energy currency of the cell that stores the energy in the form of phosphate bonds. When this bond breaks energy releases.

DNA and RNA are the genetic material of the living organism.
So the correct option is 'ATP'.

Multiple choice zoology respiration in organisms active transport and passive transport types of plant transport atp

In ATP, high energy bond is present between 

  1. Nucleoside and phosphate group

  2. Sugar and phosphate group

  3. Base and phosphate group

  4. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
ATP is known as energy currency of the cell. It has three phosphate out of which one is directly attached to the ribose with phosphate ester bond and it is low energy bond. The bond between two phosphate groups is a phosphoanhydride bond which is considered as high energy bond. So ATP has two high energy phosphoanhydride bonds.
So, the correct answer is option D.
Multiple choice

Which of the following is a component of a nucleotide?

  1. Adenine

  2. Ribose

  3. Phosphate

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

A nucleotide consists of a nitrogenous base (adenine, thymine, guanine, cytosine, or uracil), a pentose sugar (ribose or deoxyribose), and a phosphate group.

Multiple choice

What is the difference between DNA and RNA?

  1. DNA contains deoxyribose, while RNA contains ribose.

  2. DNA has a double-stranded structure, while RNA has a single-stranded structure.

  3. DNA contains thymine, while RNA contains uracil.

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

DNA differs from RNA in several ways: DNA contains deoxyribose sugar, while RNA contains ribose sugar; DNA has a double-stranded structure, while RNA has a single-stranded structure; DNA contains thymine, while RNA contains uracil.

Multiple choice

What is a codon?

  1. A sequence of three nucleotides that codes for a specific amino acid.

  2. A sequence of three nucleotides that codes for a specific protein.

  3. A sequence of three nucleotides that codes for a specific RNA molecule.

  4. A sequence of three nucleotides that codes for a specific DNA molecule.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A codon is a sequence of three nucleotides that codes for a specific amino acid, the building blocks of proteins.

Multiple choice

What is an anticodon?

  1. A sequence of three nucleotides that is complementary to a codon.

  2. A sequence of three nucleotides that is identical to a codon.

  3. A sequence of three nucleotides that is unrelated to a codon.

  4. A sequence of three nucleotides that is the reverse complement of a codon.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An anticodon is a sequence of three nucleotides in a transfer RNA (tRNA) molecule that is complementary to a codon in messenger RNA (mRNA), allowing for the specific recognition and binding of tRNA to mRNA during protein synthesis.