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 bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

Find out the correct answers out of the following discoveries
1. Griffith-Transformation
2. Gamow-Triplet code
3. Miescher-Nucieic acid

  1. 1, 2 and 3 correct

  2. 1 and 2 correct, 3 false

  3. 1 correct, 2 and 3 false

  4. 1 and 3 correct, 2 false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Griffith discovered transformation, Gamow proposed the triplet nature of the genetic code, and Miescher first isolated nucleic acids (nuclein). All are correct.

Multiple choice bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

In a 3.2K bp long piece of DNA, 820 adenine bases were found. What would be the number of cytosine bases

  1. 1480

  2. 740

  3. 560

  4. 780
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In double-stranded DNA, A pairs with T and G pairs with C. If there are 820 adenine bases, there must be 820 thymine bases, totaling 1640 bases. The remaining bases are 3200 - 1640 = 1560, which are split equally between G and C, so 1560 / 2 = 780 cytosine bases.

Multiple choice bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

Teminism is

  1. Central dogma reverse

  2. Central dogma of molecular biology

  3. Circular flow of hereditary information

  4. Effect of cytoplasm on functioning of DNA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Teminism refers to the reverse of the central dogma - the flow of information from RNA back to DNA via reverse transcription. Howard Temin's work on retroviruses showed that the dogma was not unidirectional. Option B is the standard central dogma, C refers to something else, and D is unrelated.

Multiple choice dna replication replication and protein synthesis nucleic acids and protein synthesis heredity biology

DNA replication is

  1. Conservative and discontinuous

  2. Semiconservative and semidiscontinuous

  3. Semiconservative and discontinuous

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

DNA replication is semiconservative, and because the two strands are antiparallel, one strand (leading) is synthesized continuously while the other (lagging) is synthesized discontinuously in Okazaki fragments.

Multiple choice biology breeding and biotechnology method of plant breeding for crop improvement plant breeding for food production biotechnology

Mutation is a

  1. Radioactive mutagens

  2. Chemical mutagens

  3. Radiation mutagens

  4. Change in base sequence
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 A mutation is a permanent change in the sequence of DNA. Mutations can be caused by external (exogenous) or endogenous (native) factors, or they may be caused by errors in the cellular machinery. Physical or chemical agents that induce mutations in DNA are called mutagens and are said to be mutagenic. Exogenous factors: environmental factors such as sunlight, radiation, and smoking can cause mutations. Endogenous factors: errors during DNA replication can lead to genetic changes as can toxic by-products of cellular metabolism.

Multiple choice expression of gene inherited changes biology

Eucaryotic genome differs from procaryotic genome in

  1. DNA is circular arid single-stranded in procaryotes

  2. Intervening sequences are present in eucaryotic DNA

  3. DNA is coinplexed with histones in procaryotes

  4. DNA is organised into operons in eucaryotes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Eukaryotic genes are characterized by split gene organization, meaning they contain non-coding intervening sequences called introns that are removed during RNA processing. Prokaryotic genomes generally lack these introns.

Multiple choice expression of gene inherited changes biology

Choose the correct answers from the alternatives given.
The prokaryotic genetic system contains:       

  1. either DNA or histones

  2. neither DNA nor histones

  3. DNA and histones

  4. DNA but no histones
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The prokaryotic genetic system does not have a nucleus in their cell but the genome in a prokaryote is held within a DNA in the cytosol called nucleoid.

Eukaryotes have DNA wrapped around the histones but prokaryotes do not contain histones.
Hence, the correct answer is, 'DNA but no histones'.

Multiple choice zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

The two polynucleotide strands of DNA are held together by 

  1. Hydrogen bonds

  2. Covalent bonds

  3. Metallic bonds

  4. Ionic bonds

  5. Polar covalent bonds
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Two polynucleotide chains of DNA are wound around the same axis and are held together by complementary base pairing between nitrogenous bases of two strands in the same plane. Adenine of one strand forms two hydrogen bonds with thymine of other strand and guanine forms three hydrogen bonds with cytosine.  The two bases forming hydrogen bonds to joins the polynucleotide strands together are present in the same plane. Thus, the correct answer is A.

Multiple choice zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

Which of the following bonds link the base of one chain and the base of other chain of DNA?

  1. Hydrogen bonds

  2. Covalent bonds

  3. Ionic bonds

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

As per Watson and Crick standard base pairing rules, adenine forms double hydrogen bond with thymine and guanine forms triple hydrogen bond with cytosine. Hence, content of adenine is equal to content of thymine and content of guanine is equal to content of cytosine.

Multiple choice zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

The distance between two nucleotide pairs of DNA is

  1. 0.34 nm
  2. 34$\mathring A$
  3. $3.4 \:\mu $m

  4. 34 nm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nucleotides are organic molecules that serve as the monomers, or subunits, of nucleic acids like DNA and RNA. The building blocks of nucleic acids, nucleotides are composed of a nitrogenous base, a five-carbon sugar-ribose or deoxyribose, and at least one phosphate group. Thus, a nucleoside plus a phosphate group yields a nucleotide. The distance between two nucleotide pairs in DNA is 0.34nm.

Multiple choice zoology structure of chromosome, cell cycle and cell division structure of dna nucleic acid heredity and inheritance

Which of the following is not present in genetic material?

  1. Cytosine

  2. Thymine

  3. Arginine

  4. Guanine

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

RNA and DNA are genetic materials. Cytosine, Thymine, Guanine, and Uracil are all nitrogenous bases. They are present in RNA. Uracil is replaced by adenine in DNA. Arginine is an amino acid which is basic in nature. It is the building block of protein. 

Hence, 'Arginine' is the right answer.