Biology

DNA and Genetics

985 Questions

DNA and genetics questions explore molecular biology, DNA replication, and genetic engineering techniques. These topics are essential for various competitive exams requiring a strong foundation in life sciences. Practice these questions to understand complex biological processes thoroughly.

DNA replication mechanismsGenetic engineering techniquesGene editing toolsPolymerase chain reactionDNA sequencing methods

DNA and Genetics Questions

Multiple choice

DNA is an example of 

  1. lipid

  2. carbohydrate

  3. protein

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

DNA stands for Deoxyribonucleic Acid, which classifies it as a nucleic acid. It is a polymer of nucleotides.

Multiple choice

An actively dividing culture of E. coli with radioactive THYMINE; daughter cells would have

  1. one daughter cell radioactive, not the other

  2. DNA in both daughter cells would be radioactive

  3. neither of the daughter cells would be radioactive

  4. all four bases of the DNA would be radioactive
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA replication is semi-conservative. Each daughter cell receives one original strand and one newly synthesized strand. Since the thymine in the medium is radioactive, the new strands in both daughter cells will incorporate it, making both cells radioactive.

Multiple choice

Continuous elongation of a new DNA strand along one strand of DNA

  1. requires the action of DNA ligase as well as polymerase

  2. occurs b/c DNA ligase can only elongate 3' → 5' direction

  3. occurs on the LEADING strand

  4. occurs on the LAGGING strand
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The leading strand is synthesized continuously in the direction of the replication fork movement, while the lagging strand is synthesized discontinuously.

Multiple choice

Transformation involves

  1. uptake of external genetic material, one bacteria to another

  2. creation of a strand of RNA from a DNA molecule

  3. infection of bacterial cells by phage

  4. replication of DNA along the lagging strand
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Transformation is the process by which a bacterium takes up naked DNA from its environment and incorporates it into its own genome.

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

The number of linkage group in E.coli is/are

  1. 4

  2. 2

  3. 1

  4. 5
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The number of linkage groups equals the number of chromosomes in the basic set. The number of linkage groups in an organism is equal to the haploid number of its chromosomes. Example - In Drosophila, the haploid number is n = 4, so linkage group is 4. But the number of linkage group is prokaryotes (bacteria, like E. coli) is one. This is because bacteria being prokaryotes have only a single circular chromosome.

So, the correct answer is '1'.

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

Which enzyme is responsible for linking the fragments of DNA?

  1. DNA polymerase III

  2. Endonuclease

  3. DNA polymerase I

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

DNA Ligase is the enzyme which helps in joining the fragments of DNA, basically, it acts as a glue. In the given options endonuclease helps in cutting the DNA into fragments it cleaves the polynucleotide chain by acting on the nucleotides by breaking the hydrogen bonds between them, whereas DNA polymerases synthesize the DNA molecule from deoxyribonucleotides. So, the correct answer is "DNA ligase".

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

If one chain of a DNP molecule has the base order $5$' ATTGACGT $3$'. Then the base order of its complementary chain will be.

  1. $3'$ATTGACGT$5'$
  2. $5'$TGCAGTTA$3'$
  3. $5'$TUUCTGCU$3'$
  4. $3'$TAACTGCA$5'$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA strands are antiparallel and complementary, with A pairing with T and G pairing with C. Given the 5' to 3' strand 5' ATTGACGT 3', the complementary strand must run in the 3' to 5' direction and have the matching bases: 3' TAACTGCA 5'.

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

Having become an expert on gel electrophoresis, you are asked to examine a gel for a colleague. Where would you find the smallest segments of DNA?

  1. Near the positive electrode, farthest away from the wells

  2. Near the negative electrode, close to the wells

  3. Near the negative electrode, farthest away from the wells

  4. Near the middle, they tend to slow down after the first few minutes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since DNA is itself negatively charged, it would move towards the positive electrode. In gel electrophoresis, DNA fragments are separated on the basis of charge and masses. Thus, smaller the DNA fragment farther it moves from the well.

So, the correct option is A.

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

Gel electrophoresis is used for

  1. Construction of recombinant DNA by joining with cloning vectors

  2. Isolation of DNA molecules

  3. Cutting of DNA into fragments

  4. Separation of DNA fragments according to their size
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Gel electrophoresis is used to separate macromolecules like DNA, RNA and proteins. DNA fragments are separated according to their size. 

So, the correct option is 'Option D' .