Biology

Molecular Biology and Genetics

717 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 applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

If the initial number of template DNA molecules in a PCR reaction is $1000$, the number of product DNA molecules at the end of $20$ cycles will be closest to.

  1. $10^3$
  2. $10^6$
  3. $10^9$
  4. $10^{12}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The number of DNA molecules after n cycles is calculated as N = N0 * 2^n. Here, N0 = 1000 and n = 20. So, N = 1000 * 2^20. Since 2^10 is approximately 10^3, 2^20 is approximately 10^6. Thus, 1000 * 10^6 = 10^9.

Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Which does not describe a function of the DNA polymerase molecule?

  1. Recognise the free nucleotide that pairs with the base on the template strand of DNA

  2. Read the strand of template DNA and recognise the base there

  3. Proofread to ensure that the proper base has been incorporated

  4. Make the proper nucleotide to match with the base read on the template strand
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA polymerase is an enzyme that synthesizes DNA molecules from deoxyribonucleotides, the building blocks of DNA. The function of DNA polymerase is to replicate, proofread and repair DNA.DNA polymerases add nucleotide bases only when an RNA primer, a short piece of RNA, is already present. 

So, the correct option is 'Make the proper nucleotide to match with the base read on the template strand'.

Multiple choice botany the mitotic cell cycle chromosome and its structure chromosome nucleus and chromosome

Most of the DNA of living beings is present in the 

  1. Cytosome

  2. Nucleosome

  3. Chromosme

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

A chromosome is composed of DNA and proteins. DNA are the hereditary units which mainly carries the information from one generation to the other. The functional segments of the DNA are known as genes. Proteins are mainly present as histones which form a complex structure known as a nucleosome.

So, the correct answer is option C.

Multiple choice evs identifying the plants absorption of water from the soil root system the root system

DNA content of quiescent zone is

  1. High

  2. Low

  3. Very high

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

The quiescent center is a small group of cells with low mitotic activity (no cell division). Quiescent center are to be found at the tips of growing roots, in the root meristem and are surrounded by groups of dividing cells.
Thus, the correct answer is option B.

Multiple choice business organisation and correspondence environmental pollution and industries air pollution and its effects the environment and us environment and conservation

Large increase in absorption of UV- radiation of 260 nm by melted DNA duplex is called

  1. Gaidukov phenomenon

  2. Position effect

  3. DNA compaction

  4. Hyperchromic effect
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • The increase in the absorbance of a material is known as hyperchromicity and the effect is known as the hyperchromic effect.
  • The DNA molecule gets denatured by the hyperchromicity.
  • The absorption of UV radiation by DNA molecule increases when the two single DNA strands get separated by heat or by a heat denaturant or by changing the pH level.
  • So, the correct answer is 'Hyperchromic effect'.
Multiple choice biology micro organisms non cellular organism : virus world of virus bacteria - introduction, shape and structure

Cryptogram of a virus (Gibbs and Harrison 1968) has $4$ pairs of symbols to be used in virus classification. The pair $1$ indicates

  1. Type of nucleic acid in virus/ structure of nucleic acid

  2. Molecular weight of nucleic acid/ percentage of nucleic acid

  3. Shape of virus particle/ shape of capsid

  4. Kind of host infected/ kind of vector
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Cryptogram code is proposed by Gibbs and Harrison (1968) to describe the virus. The code consists of 4 pairs of symbols. 
The first pair indicates- The type of nucleic acid/number of strands in the particular nucleic acids. For example cryptogram of Poliovirus is written as R/l: 2.5/30: S/S: V/O.
So, the correct answer is option A, Type of nucleic acid in virus/ structure of nucleic acid. 
Multiple choice biology option b: biotechnology and bioinformatics pcr cutting, insertion and ligation of dna gene cloning procedure

A probe which is a molecule used to locate specific sequences in a mixture of DNA or RNA molecules could be __________________.

  1. A single stranded RNA

  2. A single stranded DNA

  3. Either RNA or DNA

  4. Can be ssDNA but not ssRNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The molecular probes are usually single-stranded places of DNA (sometimes RNAs) labeled with radioisotopes such as phosphorus- 32. Molecular probes are available for many genetic disorders such as Duchenne muscular dystrophy, cystic fibrosis, Tay-Sachs disease.

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 bio-chemistry digestion digestive glands liver pancreas

In Escherichia coli, how many codons code for the standard amino-acids?

  1. $64$
  2. $60$
  3. $61$
  4. $20$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

There are 64 total codons. Of these, 61 code for the 20 standard amino acids, while the remaining 3 are stop codons that do not code for any amino acid.

Multiple choice bio-chemistry carbohydrate metabolism energy output living organisms and energy production respiration in cell

What is the energy coin of a cell?

  1. DNA

  2. RNA

  3. ATP

  4. Minerals
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • During cellular metabolism, energy is frequently exchanged between endergonic and exergonic reactions and molecules.
  • The ATP is a universal energy currency, which is used in these cellular energy exchanges.
  • The reason has been that is ATP can be formed easily by the process of phosphorylation of ADP as suggested by the chemiosmotic theory.
  • Further, one molecule of ATP has two terminal high energy acid anhydride bonds, which can break easily to provide energy. 
  • Therefore, ATP can be both formed easily as well as broken easily. 

    Hence, correct option is C.
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.