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 structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

In relation to double helical bacterial DNA, match list-I(Parameter) with List-II(Value) and select the correct answer using the codes given the lists.

List-I List-II
a. Diameter of the helix $1$. $34A'$
b. Distance between two adjacent bases $2$. $20A'$
c. Distance between two complete turns $3$. $3A'$
d. Length of the hydrogen bond $4$. $3.4A'$
  1. A-$1$, B-$3$, C-$2$, D-$4$
  2. A-$2$, B-$3$, C-$1$, D-$4$
  3. A-$1$, B-$4$, C-$2$, D-$3$
  4. A-$2$, B-$4$, C-$1$, D-$3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

In aqueous solution, the alcidine molecules bind to DNA by inserting themselves between adjacent base pairs. The process is called ______________.

  1. Depreciation

  2. Substitution

  3. Mutation

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

Intercalation is the process where planar molecules slip between adjacent base pairs in the DNA double helix, causing distortion and frameshift mutations during replication. Depreciation, substitution, and mutation are unrelated or broader terms.

Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

Which of the following pairs is/are correctly matched?
a. E.coli - Circular DNA
b. Tobacco Single - Stranded RNA mosaic virus
c. Reo virus - Double-stranded RNA
Select the correct answer using the codes given.

  1. $1$ alone
  2. $1, 2$ and $3$
  3. $1$ and $3$
  4. $2$ and $3$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

All three given statements are correct. E. coli contains circular double-stranded DNA, tobacco mosaic virus possesses single-stranded RNA, and reoviruses are known for having a double-stranded RNA genome.

Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

The genetic material in the virus $fX _{174}$ is?

  1. Single-stranded RNA

  2. Double-stranded RNA

  3. Single-stranded DNA

  4. Double-stranded DNA
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Bacteriophage fX174 is a classic model organism known for having a single-stranded DNA genome. Most other common viruses feature double-stranded DNA or single/double-stranded RNA.

Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

If the sequence of bases in coding strand of DNA is ATTCGATG, then the sequence of bases in mRNA will be

  1. TAAGCTAC

  2. UAAGCUAC

  3. ATTCGATG

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

mRNA strand is complementary to template strand of DNA, while coding strand has same sequence as RNA (except thymine at the place of uracil). Hence, the sequence of bases in mRNA will be AUUCGAUG.

Multiple choice structure of dna and rna nucleic acids and polynucleotides nucleic acids and protein synthesis molecular biology biology

If one strand of DNA has the base sequence AAGCAA, the complementary strand has which of the following sequences?

  1. UUCGUU

  2. TTCGTT

  3. AAGCM

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

The DNA (Deoxyribonucleic acid) molecules have four nucleotide bases along with sugar and phosphate backbone, these four bases are adenine, guanine, thymine, and cytosine. Adenine and thymine are bonded together by two hydrogen bonds while guanine and cytosine are bonded by three hydrogen bonds.

So, the correct option is 'TTCGTT'.

Multiple choice zoology global environmental change causes of greenhouse effect global warming adaptation in animals

Ultraviolet light causes

  1. Destruction of hydrogen bonds between complementary DNA strands

  2. Photodynamic action

  3. Sticky metaphases

  4. Formation of pyrimidines
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
DNA is one of the prime molecules and provides stability for proper functioning and existence of all living systems. Ultra-violet radiations are power molecules whose exposure breaks the hydrogen bonds of dna and thus altering its structure and affecting the genomic stability.
So, the correct answer is option A.
Multiple choice biology biodiversity and classification monera five kingdoms of living organisms biodiversity and need of classification

Choose the correct answers from the alternatives given:
All monerans

  1. lack an endoplasmic reticulum

  2. contain DNA and RNA

  3. demonstrate a long circular strand of DNA not found enclosed in a nuclear membrane

  4. all of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Monera is a kingdom that contains unicellular organisms with a prokaryotic cell organization such as bacteria. They are single-celled organisms with an absence of membrane-bound organelles. The nucleus and endoplasmic reticulum, as well as other organelles, are absent. 
  • Hence, the correct answer is 'All of the above'.
Multiple choice biology biodiversity and classification monera five kingdoms of living organisms biodiversity and need of classification

All monerans ___________________.

  1. Contain $DNA$ and $RNA$
  2. Demonstrate a long circular strand of $DNA$, not formed enclosed in a nuclear membrane

  3. Are bacteria

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

Monerans are prokaryotes, meaning they lack a membrane-bound nucleus (they have a nucleoid with circular DNA). They are not exclusively bacteria (they include archaea), but the options provided are often grouped in general biology contexts.

Multiple choice botany the world of microbes bacteria - introduction, shape and structure bacteria: types and structure bacteria; benefits and harmful effects non cellular organism : virus world of virus

Bacterial genome consist of 

  1. Circular, ssRNA

  2. Circular, dsDNA

  3. Linear, triple stranded DNA

  4. zig-zag DNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bacterial genome as that of a bacteria E.coli consists of Double-stranded DNA (ds DNA) which is circular which means it doesn't have ends like eukaryotic chromosomes. E.coli consists of 4.6 x 10$^6$ base pairs(bp).

So, the correct answer is 'Circular, dsDNA'.

Multiple choice botany the world of microbes bacteria - introduction, shape and structure bacteria: types and structure bacteria; benefits and harmful effects non cellular organism : virus world of virus

DNA of Escherichia coli is

  1. dsDNA and circular

  2. dsDNA and linear

  3. ssDNA and linear

  4. ssDNA and circular.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Escherichia coli is a Gram-negative, facultatively anaerobic bacteria. It is found in the intestine of warm-blooded organisms. It has one circular chromosome. The chromosome contains double-stranded DNA. It may contain some circular plasmids as well as extrachromosomal material.

Thus, the correct answer is option A.

Multiple choice botany option b: biotechnology and bioinformatics gram staining microbiology: organisms in industry cell wall and cell membrane

Bacteria were grown in a medium containing heavy isotope of nitrogen (N15) for many generations and all their DNA contained many heavy nitrogen only. A bacterium of this type was transferred to normal medium and allowed to duplicate. After two divisions of heavy DNA is likely to be that

  1. Only one daughter cell will have heavy DNA

  2. Two daughter cells have normal DNA and other two

  3. All daughter cells have heavy DNA

  4. Half daughter cells have heavy DNA and other half have normal DNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

After two divisions, four bacterial cells are formed in which two daughter bacterial cells have normal DNA and other two have both normal and heavy DNA because DNA replicates by semiconservative method in bacteria.

Multiple choice biology selection and evolution ethology animal behaviour natural selection

Which of the following codon does not justify degeneracy rule?

  1. UGG

  2. CUG

  3. GGG

  4. GAG.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Degeneracy is the rule in of genetic code which states that one amino acid can be produced by one or more codon. The example is UUU and UUG both code for same amino acid i.e phenylalanine.Tryptophan is only produced by UGG.
So the correct option is 'UGG'.