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

Assume that the occurrence of nitrogen bases in adjacent positions in a DNA strand is random. Identify the minimum number of nucleotides in a DNA strand where GAAT can occur once on the basis of probability

  1. 512

  2. 256

  3. 4096

  4. 1024
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The probability of a specific 4-nucleotide sequence occurring at any position is (1/4)^4 = 1/256. To expect this sequence to occur once, you need 256 positions. Thus, 256 nucleotides are required.

Multiple choice polarisation of light polarisation wave optics optics physics

The helical structures of nucleic acids can be studied by using :

  1. Interference phenomenon

  2. Diffraction pattern

  3. Polarised light

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

Polarised light is used to studied helical structures of nucleic acids using different methods such as optical rotatory dispersion. In this method due to refractive indices of the medium for left and right circularly polarised light reflects the structural details of such molecular complexes.

Multiple choice polarisation of light polarisation wave optics optics physics

Consider the following statements A and B. Identify the correct statements.
(A) Polarized light can be used to study the helical structure of nucleic acids.
(B) Optical axis is a direction and not any particular line in the crystal.

  1. A and B are correct

  2. A and B are wrong

  3. A is correct and B is wrong

  4. A is wrong and B is correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nucleic acid is an optically active medium. When circularly polarized light passes through an absorbing optically active medium, the speeds between right and left polarizations differ as well as their wavelengths. This can be used to study the helical structure of nucleic acids.
An optical axis is a line along which there is some degree of rotational symmetry in an optical system. Thus it is a particular direction and not any
random line.

Multiple choice biology health and diseases non-infectious diseases non infectious diseases categories of diseases

Which protein is called "guardian of genome"?

  1. $P$ $53$
  2. Cyclin $D$
  3. $CDK$ $4$
  4. $Rb$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

p53 is a protein is known as  "guardian of genome" because it regulates cellular apoptosis and cellular growth to maintain the integrity of the human genome. It is also known as policeman of oncogenes because it suppresses the mutation and prevents oncogenesis.

So, the correct answer is option A.

Multiple choice biology health and diseases non-infectious diseases non infectious diseases categories of diseases

Genes involved in cancer are 

  1. Cancer genes

  2. Oncogenes

  3. Tumour genes

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

An oncogene is a gene that has the potential to cause cancer. In tumour cells, they are often mutated or expressed at high levels. Activated oncogenes can cause those cells designated for apoptosis (programmed cell death) to survive and proliferate instead. Most oncogenes began as proto-oncogenes which are normal genes involved in cell growth and proliferation or inhibition of apoptosis.

So, the correct answer is 'Oncogenes'.

Multiple choice biology health and diseases non-infectious diseases non infectious diseases categories of diseases

Cancer is caused due to activation of ......to .......and /or inactivation of

  1. Oncogene,tumour suppressor gene,protooncogene

  2. Tumour suppressor gene,oncogene protooncogene

  3. Protooncogene ,oncogene,tumour suppressor gene

  4. Oncogene,protooncogene,tumour suppressor gene
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. A proto-oncogene is a normal gene that could become an oncogene due to mutations and cancer. Proto-oncogenes code for proteins that help to regulate cell growth and differentiation. A tumour suppressor gene or antioncogene is a gene that protects a cell from one step on the path to cancer. Cancer develops due to inactivation of a tumour suppressor gene.

So, the correct answer is 'Protooncogene, oncogene, tumour suppressor gene'.

Multiple choice biology health and diseases non-infectious diseases non infectious diseases categories of diseases

Which of the following statements in not true for cancer cells in relation to mutations :-

  1. Mutations inhibits production of telomerase

  2. Mutations in proto-oncogenes accelerate the cell cycle

  3. Mutations destroy telomerase inhibitor

  4. Mutations inactivate the cell control
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cancer cells typically maintain or increase telomerase activity to achieve immortality, allowing them to divide indefinitely. Inhibiting telomerase production would stop cancer cell proliferation, not promote it.

Multiple choice zoology respiration in organisms active transport and passive transport types of plant transport atp

In ATP, high energy bond is present between 

  1. Nucleoside and phosphate group

  2. Sugar and phosphate group

  3. Base and phosphate group

  4. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
ATP is known as energy currency of the cell. It has three phosphate out of which one is directly attached to the ribose with phosphate ester bond and it is low energy bond. The bond between two phosphate groups is a phosphoanhydride bond which is considered as high energy bond. So ATP has two high energy phosphoanhydride bonds.
So, the correct answer is option D.
Multiple choice

Which of the following is a component of a nucleotide?

  1. Adenine

  2. Ribose

  3. Phosphate

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

A nucleotide consists of a nitrogenous base (adenine, thymine, guanine, cytosine, or uracil), a pentose sugar (ribose or deoxyribose), and a phosphate group.

Multiple choice

What is the difference between DNA and RNA?

  1. DNA contains deoxyribose, while RNA contains ribose.

  2. DNA has a double-stranded structure, while RNA has a single-stranded structure.

  3. DNA contains thymine, while RNA contains uracil.

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

DNA differs from RNA in several ways: DNA contains deoxyribose sugar, while RNA contains ribose sugar; DNA has a double-stranded structure, while RNA has a single-stranded structure; DNA contains thymine, while RNA contains uracil.

Multiple choice

What is a codon?

  1. A sequence of three nucleotides that codes for a specific amino acid.

  2. A sequence of three nucleotides that codes for a specific protein.

  3. A sequence of three nucleotides that codes for a specific RNA molecule.

  4. A sequence of three nucleotides that codes for a specific DNA molecule.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A codon is a sequence of three nucleotides that codes for a specific amino acid, the building blocks of proteins.

Multiple choice

What is an anticodon?

  1. A sequence of three nucleotides that is complementary to a codon.

  2. A sequence of three nucleotides that is identical to a codon.

  3. A sequence of three nucleotides that is unrelated to a codon.

  4. A sequence of three nucleotides that is the reverse complement of a codon.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An anticodon is a sequence of three nucleotides in a transfer RNA (tRNA) molecule that is complementary to a codon in messenger RNA (mRNA), allowing for the specific recognition and binding of tRNA to mRNA during protein synthesis.

Multiple choice

What discovery unlocked the secrets of DNA?

  1. DNA Structure

  2. Genetic Code

  3. DNA Replication

  4. Gene Editing
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The discovery of the DNA structure by James Watson and Francis Crick in 1953 laid the foundation for understanding genetics and revolutionized the field of biology.