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 botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

Which of the following is an INCORRECT statement regarding genetic material?

  1. Genes are made up of DNA

  2. Chromatin is made up of DNA

  3. Histones are proteins to which chromatin is bound

  4. DNA is made up of genes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In biology, a gene is a sequence of DNA or RNA that codes for a molecule that has a function. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. However the inverse is incorrect. 

So the correct option is "DNA is made up of genes".

Multiple choice botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

Which of the following part of DNA contains genes?

  1. Junk DNA

  2. Coding DNA

  3. Whole DNA

  4. Any of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gene is present in the coding region of the DNA. In eukaryotes, gene is made up of both introns and exons. So, the correct option is "Coding DNA".

Multiple choice botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

Gene library or DNA library has collection of

  1. DNA and RNA

  2. Any one type of gene of Organism

  3. c DNA only

  4. All possible genes of all organisms
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • A Gene library or DNA library is a comprehensive collection of cloned DNA fragments from a cell, tissue, or organism.
  • DNA libraries can be used to isolate a specific gene of interest as they generally include at least one fragment that contains the gene.
  • Hence Gene library or DNA library has a collection of c DNA only.
  • So, the correct answer is 'c DNA only'.
Multiple choice biology cell-the basic unit of life number and shape of cells unicellular and multicellular organisms cell parameters diversity and classification in animals

Correct arrangement of the following in increasing size is
(i) Width of biological membrane.
(ii) Diameter of E.coli DNA
(iii) Human ribosome
(iv) Length of E.coli DNA
(v) Diameter of human liver cell.

  1. i, iii, ii, iv, v

  2. ii, i, iii, iv, v

  3. i, iii, ii, v, iv

  4. ii, iii, i, iv, v
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Answer :
i) Biological Membranes are typically 7.5–10 nm in thickness with two regular layers of lipid molecules.
ii) E coli cells are typically rod-shaped, and are about 2.0 μm long and 0.25–1.0 μm in diameter.
iii) Prokaryotic ribosomes are around 20 nm in diameter.
iv) E.coli chromosomes have about 4.7 x 10^6 base pairs which results in a length of 1.6 mm.
v) Diameter of human liver cell 50–100µm
So correct answer is option C. i, iii, ii, v, iv.

Multiple choice biomacromolecules biotechnology cell biology and biotechnology biomolecules biology

Which of the following is a false statements?

  1. DNA is chemically less reactive, as compared to RNA.

  2. RNA mutate at a faster rate, as compared to DNA.

  3. Guanyl transferase enzyme helps in capping process during splicing of hn-RNA.

  4. Sweetness index of saccharine is 10,000.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA is chemically less reactive as compared to RNA.
RNA mutate at a faster rate because from DNA, RNA is formed duirng transcription and there are more chances of mutation during this phase.
Saccharin is an artificial sweetener with effectively no food energy which is about 300-400 times as sweet as sucrose.
hnRNA is heterogenous nuclear RNA. Its processing includes addition of a cap. The cap is 5'methyl guanosine that is added immediately after the start of the transcription. This reaction is catalysed by guanylyl transferase.

Multiple choice biomacromolecules biotechnology cell biology and biotechnology biomolecules biology

Purine  base with methyl substituents occurring in plants are

  1. Caffeine

  2. Theophylline

  3. Theobromine

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

A number of purine bases containing methyl substituents occur in plants and plant products and many of them have pharmacological properties. For example Theophylline is chemically 1,3-dimethylxanthine. It is found in tea. Theobromine occurs in cocoa. It is chemically 3,7-dimethylxanthine. Caffeine is present in coffee. It is chemically 1,3,7-trimethylxanthine. 

Multiple choice bio-chemistry biochemical techniques manipulation of dna electrophoresis isolation and separation of dna

A mixture containing DNA fragments, A, B, C and D, with molecular weights of $A + B =C, A>B$ and $D>C$, was subjected to agarose gel electrophoresis. The positions of these fragments from cathode to anoe sides of the gel would be

  1. $D, C, A, B$
  2. $A, B, C, D$
  3. $C, B, A, D$
  4. $B, A, D, C$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gel electrophoresis is the techniques by which negatively charged DNA fragments separate according to their molecular mass and the principle says that lighter goes the maximum distance that means heavy DNA stops first as D is heavier it separates first while B at last.

So the correct option is 'D,C,A,B'.

Multiple choice bio-chemistry biochemical techniques manipulation of dna electrophoresis isolation and separation of dna

In gel electrophoresis, differential mobility of DNA depends upon

  1. Helical nature of DNA

  2. Double stranded nature of DNA

  3. Charge and size of DNA

  4. Hydrogen bonding between bases
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

DNA is negatively charged due to its phosphate backbone, so it moves toward the anode. The gel matrix acts as a sieve, where smaller fragments move more easily than larger ones, meaning separation depends on both charge and size.

Multiple choice bio-chemistry biochemical techniques manipulation of dna electrophoresis isolation and separation of dna

A correct pair of characteristics of molecular probe are:
a. Very long molecule
b. Double stranded
c. DNA or RNA
d. Complementary to a part of desired gene.

  1. a,b

  2. b,c

  3. c,d

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

A molecular probe is a single-stranded DNA or RNA molecule that is complementary to the target sequence of interest, allowing it to bind specifically to that sequence.

Multiple choice bio-chemistry biochemical techniques manipulation of dna electrophoresis isolation and separation of dna

When heated, the hydrogen bonds between the complementary strands of DNA break and the 2 strands separate in a process called melting. Which of the following pieces of DNA will require maximum temperature for melting?

  1. $3'\quad AAGGTATACAAT\quad 5'\\ 5'\quad TTCCATATGTTA\quad 3'$
  2. $3'\quad GAGCUAUCCGAG\quad 5'\\ 5'\quad CUCGAUAGGCUC\quad 3'$
  3. $3'\quad ACGTCCGCTGCG\quad 5'\\ 5'\quad TGCAGGCGACGC\quad 3'$
  4. $3'\quad ATTAGCTAGCAA\quad 5'\\ 5'\quad TAATCGATCGTT\quad 3'$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

DNA melting temperature is higher for sequences with more G-C base pairs because G-C pairs have three hydrogen bonds, while A-T pairs have only two. Option C contains the highest proportion of G-C pairs, requiring the most energy to separate.

Multiple choice biology concept of life theories of the origin of life origin of life the origin of cells and cell division

A novel species with double stranded genetic material consists of 5 bases namely P. Q. R. S. T. with percentages given below. 

P Q R S T
Percentage  22 28 22 12 16

Based on the above information, which ONE of the following infrences is NOT supported by the observation?

  1. S- base pairs with T, and Q base pairs with R

  2. S base pairs with Q,and T base pairs with Q

  3. P base pairs with R, and S base pairs with Q

  4. P base pairs with R, and T base pairs with Q
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

P and R have the same percentage hence they must bond with each other.

The total percentage of S and T is equal to the percentage of Q hence Q binds to both S and T.
So the correct answer is ' Sbase pairs with T, and Q base pairs with R'.