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 does DNA stand for?

  1. Dominant Nuclear Acid

  2. Daily Nursing Applejuice

  3. Deoxyribonucleic Acid

  4. Dino Nuggets Arithmetic
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

DNA is an acronym for Deoxyribonucleic Acid, which is the molecule that carries the genetic instructions for life.

Multiple choice

How can mutations in regulatory regions affect a gene

  1. How much the gene is transcribed

  2. Whether or not it is expressed at all

  3. Both

  4. Neither (no effect)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Regulatory regions control gene expression. Mutations here can change the rate of transcription (how much protein is made) or disrupt the binding sites entirely, preventing expression.

Multiple choice

Is DNA or RNA more susceptible to mutation?

  1. DNA

  2. RNA

  3. Same
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

RNA is more susceptible to mutation because it is single-stranded and lacks the robust error-correction machinery that double-stranded DNA uses during replication.

Multiple choice

In DNA, cytosine pairs with

  1. guanine

  2. thymine

  3. adenine
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the structure of DNA, the nitrogenous base cytosine (C) always forms a hydrogen bond with guanine (G) according to Chargaff's rules.

Multiple choice

the spiral staircase structure of DNA known as

  1. Crick and Watson’s ladder

  2. Chutes and Ladders

  3. genetic code

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

The double helix is the term used to describe the physical structure of the DNA molecule, which consists of two strands that wind around each other.

Multiple choice

DNA looks like a spiral staircase called a

  1. allele

  2. gene

  3. chromosome

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

The double helix is the term used to describe the twisted ladder or spiral staircase structure of the DNA molecule. The other options refer to genetic components or structures, not the shape of the molecule.

Multiple choice

DNA is packaged into threadlike structures called

  1. allele

  2. traits

  3. chromosome

  4. double helix
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chromosomes are threadlike structures made of DNA and proteins that are found in the nucleus of cells. DNA is coiled tightly around proteins to form these structures.

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

Number of linkage in a polynucleotide would be __________________.

  1. Same as number of nucleotides

  2. Twice the number of nucleotides

  3. One less than the number of nucleotides

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

In a linear polynucleotide chain, phosphodiester linkages connect adjacent nucleotides. For n nucleotides in a single chain, there are n-1 phosphodiester linkages joining them together.

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.