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 unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

The control of gene expression is more complex in eukaryotic cells because the ___________________.

  1. Gene expression differentiaties specialized cells

  2. The chromosomes are linear and more numerous

  3. Operons are controlled by more than one promoter region

  4. inhibitory or activating molecules may not help to regulate transcription
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eukaryotic gene expression is more complex because it must generate and maintain differentiated cell types (neurons vs. muscle vs. skin), each with specialized gene expression profiles. Option A correctly states this. The other options describe structural features, not regulatory complexity.

Multiple choice bio-chemistry unit of living - cell eukaryotic cell kinds of cell introduction to eukaryotic cell

Select the correct sequence of molecules in cell on the basis of molecular size from the smallest to the largest.

  1. Carbon dioxide$-$phospholipid$-$DNA polymerase$-$ribosome
  2. Phospholipid$-$DNA polymerase$-$ribosome$-$carbon dioxide
  3. Phospholipid$-$carbon dioxide$-$ribosome$-$DNA polymerase
  4. Carbon dioxide$-$DNA polymerase$-$phospholipid$-$ribosome
  5. DNA polymerase$-$ribosome$-$carbon dioxide$-$phospholipid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Carbon dioxide, has two atoms of oxygen and one atom of carbon, making it the smallest one among the given options. Phospholipids are amphipathic molecules, having phosphate head group and fatty acid tails. DNA polymerase is polypeptide enzyme while ribosomes are the assemblage of rRNA and proteins. 
The correct answer is option A.

Multiple choice botany biotechnology and its applications biotechnology in agriculture gm crops transgenic organisms

RNA interference which is employed in making tobacco plant resistant to Meloidegyne incognita is essentially involved in

  1. preventing the process of replication of DNA

  2. preventing the process of translation of mRNA

  3. preventing the process of splicing of hnRNA

  4. preventing the process of transcription
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

RNA interference is a gene-silencing process that blocks the expression of genes in the parasite when it enters the host's body.RNA is a method adopted to prevent infestation of roots of tobacco plants by a nematode Meloidogyne incognita. In RNA, a complementary RNA binds to mRNA to form a ds RNA that cannot translate and hence, its expression is blocked.

So, the correct option is 'Preventing the process of translation of mRNA'.

Multiple choice biology enzymes classification of enzyme enzymes classification and cofactors the origin of cells and cell division

Phosphodiesterases rapidly catalyze hydrolysis of sugar phosphate bond in nucleic acids.
The first digit of their E,C number can be

  1. $1$
  2. $2$
  3. $3$
  4. $6$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Phosphodiesterase is a hydrolase enzyme. So, it's EC number is 3.

EC or Enzyme Commission number is numerical classification scheme for enzymes, used to classify them according to reactions they catalyze.
So, the correct  option is '3'.

Multiple choice zoology global environmental change causes of resource depletion causes of greenhouse effect ozone layer depletion

UV light radiation cause

  1. Formation of pyrimidines

  2. Photodynamic action

  3. Breakage of hydrogen bonds in DNA

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

The UV radiations can cause mutation in the cells by altering the DNA. These are ionising radiations which can damage the structure of the DNA molecule. The UV rays can result in the formation of thymine dimers or split the hydrogen bonding. This results in distortion in the structure of DNA and the cell dies due to malfunctioning of the genetic material. 

Thus, the correct answer is option C. 

Multiple choice

Does every cell in your body contain the exact same DNA?

  1. Yes, all cells are exact clones with the same DNA.

  2. Your DNA is as haphazard as the lens flares in a Michael Bay

  3. No, there are some differences known as mosiacs

  4. DNA does what it want Its a strong independent macromolecule
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

While most cells share the same genome, somatic mutations and epigenetic changes can lead to genetic variation between cells. This phenomenon is referred to as mosaicism.

Multiple choice

Which is true for prokaryotic DNA?

  1. DNA is naked/Circular DNA/DNA found in cytoplasm

  2. DNA associated with histones/Linear DNA/DNA found in nucleus
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Prokaryotic cells lack a nucleus and membrane-bound organelles. Their DNA is typically circular, naked (not associated with histones), and located in the nucleoid region of the cytoplasm.

Multiple choice

About how long does it take for one of your cells to completely copy its DNA?

  1. 1 hour

  2. 2 days

  3. 1 week

  4. 6 months
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

While DNA replication speed varies by organism and cell type, in many rapidly dividing human cells, the process of S-phase replication typically takes several hours, with 1 hour being a common textbook approximation for the duration of the S-phase in a standard cell cycle.

Multiple choice

What molecule allows hereditary information to be passed from generation to generation?

  1. DNA

  2. Lipids

  3. ATP

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

DNA is the molecule that stores and transmits genetic instructions from parents to offspring. It contains the code necessary for building proteins and directing all cellular activities. Other molecules like lipids, ATP, and proteins serve structural, energetic, or functional roles but do not carry hereditary information.

Multiple choice

what would be the RNA strand if it was produced from the following DNA strand? ATTCCGGAGA

  1. UAAGGCCUCU

  2. TUUGGCCTCT

  3. TAAGGCCTCT

  4. TATA Box
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

During transcription, RNA is synthesized using a DNA template. Adenine (A) pairs with Uracil (U) in RNA, Thymine (T) pairs with Adenine (A), Cytosine (C) pairs with Guanine (G), and Guanine (G) pairs with Cytosine (C). Therefore, the DNA sequence ATTCCGGAGA transcribes to the RNA sequence UAAGGCCUCU.

Multiple choice

RNA contains which bases?

  1. A, T, G, C, U

  2. A, T, G, C

  3. T, G, C, U

  4. A, G, C, U
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

RNA contains the nitrogenous bases adenine (A), guanine (G), cytosine (C), and uracil (U). Unlike DNA, it does not contain thymine (T).

Multiple choice

About how much DNA do humans have in common with bananas?

  1. 10%

  2. 25%

  3. 40%

  4. 60%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Humans and bananas share about 60% of their DNA because many of the basic cellular functions, such as replicating DNA and consuming energy, are identical across all eukaryotic life. This shared genetic material highlights our deep evolutionary connections.