Biology

DNA and Genetics

1,095 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

Which of the following statements are FALSE regarding mycoplasmas? P. Discovered by Nocard and Roux. Q. Genetic material is a single stranded molecule of DNA without nuclear envelope. R. Mycoplasma cells do not contain cholesterol and cholesterol esters. S. Mycoplasmas are not affected by penicillin.

  1. Only P and Q

  2. Only P and S

  3. Only Q and R

  4. Only Q and S

  5. Only R and S
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Genetic material is present in the form of nucleoid,  which consists of a single circular double stranded molecule of DNA without nuclear envelope. Mycoplasma cells contain cholesterol and cholesterol esters, which are characteristics of animal cells and not found in true bacteria.

Multiple choice

Function of DNA topoisomerase II is to

  1. cut the single strand of DNA

  2. cut both the strands of DNA

  3. stabilize both the strands

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DNA topoisomerase II functions by creating a transient double-strand break in the DNA helix to allow another segment of DNA to pass through, thereby relieving supercoiling.

Multiple choice

Plasmid is a/an

  1. plastid

  2. extrachromosomal DNA

  3. starch granules

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

 A plasmid is a small DNA molecule within a cell that is physically separated from a chromosomal DNA and can replicate independently. They are most commonly found in bacteria as small circular, double-stranded DNA molecules; however, plasmids are sometimes present in archaea and eukaryotic organisms.

Multiple choice

Which of the following programs did Pearson and Lipman searched for similarity between a protein query sequence and any group of nucleotide sequences?

P. FastA Q. TFastA R. FastX S. TFastX

  1. Only P and Q

  2. Only P and S

  3. Only Q and R

  4. Only Q and S

  5. Only R and S
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Yes, it is correct. TFastA does a Pearson and Lipman search for similarity between a protein query sequence and any group of nucleotide sequences. TFastX does a Pearson and Lipman search for similarity between a protein query sequence and any group of nucleotide sequences, taking frameshifts into account.

Multiple choice

In which of the following cases, it is preferable to use BLASTX?

  1. If the input sequence is a protein-encoding DNA sequence.
  2. If one is looking for protein homologs encoded in newly sequenced genomes.
  3. If a DNA sequence is to be used as the query.

  1. Only 1 and 2

  2. Only 1 and 3

  3. Only 2 and 3

  4. All of these

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Yes, both are correct. If the input sequence is a protein-encoding DNA sequence, it is preferable to use BLASTX, which translates it in six open reading frames before sequence comparisons are carried out. If a DNA sequence is to be used as the query, a protein-level comparison can be done with TBLASTX. However, both programs are very computationally intensive and the search process can be very slow.

Multiple choice

Which of the following statements is/are TRUE?

  1. Praline is more accurate than Clustal.
  2. Alignment at the protein level is more sensitive than at the DNA level.
  3. Sequence alignment at the protein level is much more informative for functional and evolutionary analysis.

  1. Only 1

  2. Only 2

  3. Only 3

  4. All of these

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Yes, this is the correct answer. Praline is profile based and has the capacity to restrict alignment based on protein structure information, and is thus much more accurate than Clustal. Alignment at the protein level is more sensitive than at the DNA level. Sequence alignment directly at the DNA level can often result in frameshift errors because in DNA alignment gaps are introduced irrespective of codon boundaries. Sequence alignment at the protein level is much more informative for functional and evolutionary analysis.

Multiple choice

Which of the following are consensus-based gene prediction programs?

  1. GenomeScan
  2. EST2Genome
  3. SGP-1
  4. GeneComber
  5. DIGIT

  1. Only 1, 2 and 3

  2. Only 2 and 4

  3. Only 3 and 4

  4. Only 3, 4 and 5

  5. Only 4 and 5
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Consensus-based gene prediction programs Because different prediction programs have different levels of sensitivity and specificity, it makes sense to combine results of multiple programs based on consensus. GeneComber is a web server that combines HMMgene and GenScan prediction results. DIGIT is another consensus-based web server. It uses prediction from three ab initio programs – FGENESH, GENSCAN, and HMMgene.

Multiple choice

Which of the following statements is/are correct?

  1. LrgA and CidA are homologous holin and anti-holin proteins, respectively.
  2. CidA/LrgA holin family includes putative murine hydrolase exporters from a wide range of algae.
  3. CidA/LrgA holin regulates and influences biofilm formation by releasing DNA from lysed cells.

  1. Only 1

  2. Only 2

  3. Only 3

  4. Only 1 and 2

  5. Only 2 and 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct. CidA/LrgA holin regulates and influences biofilm formation by releasing DNA from lysed cells.

Multiple choice

Which of the following statements is/are false?

  1. In sequence assembly, k-mers are normally used during the construction of De Bruijn graphs.
  2. The choice of the k-mer size has many different effects on the sequence assembly.
  3. A lower k-mer size will increase the amount of edges stored in the graphs and decrease the amount of space required to store DNA sequence.

  1. Only 1

  2. Only 2

  3. Only 3

  4. Only 1 and 2

  5. Only 2 and 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct. A lower k-mer size will decrease the amount of edges stored in the graphs and decrease the amount of space required to store DNA sequence.