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 botany the living world archaebacteria the three domains of life classification of microbes

Thermococcus, Methanococcus and Methanobacterium exemplify

  1. Bacteria whose DNA is relaxed or positively supercoiled but which has a cytoskeleton as well as mitochondria

  2. Bacteria that contain a cytoskeleton and ribosome

  3. Archaebacteria that contain proteins homologous to eukaryotic core histones

  4. Archaebacteria that lack any histones resembling those found in eukaryotes but whose DNA is negatively supercoiled
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Archaebacteria, including the genera mentioned, are known to possess histone-like proteins that help package their DNA, similar to eukaryotic histones.

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

Polymerisation of DNA is in

  1. $3' \rightarrow 5'$ direction
  2. $5' \rightarrow 3'$ direction
  3. Both $3' \rightarrow 5'$ and $5' \rightarrow 3'$ direction

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
DNA polymerase has 5' $\rightarrow$ 3' activity. All known DNA replication systems require a free 3' hydroxyl group before synthesis can be initiated (note: the DNA temple is read in 3' to 5' direction whereas a new strand is synthesized in 5' to 3' direction).
So, the correct answer is "5' $\rightarrow$ 3' ".
Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Which one of the following palindromic base sequences in DNA can be easily cut at about the middle by some particular restriction enzyme?

  1. $5$' ______ GAATTC ________$3$

    $3$' _______ CTTAAG __________$5$'
  2. $5$' __________CACGTA _________ $3$'

    $3$'________ CTCAGT ________ $5$'
  3. $5$' ________ CGTTCG ________ $3$'

    $3$' _________ATGGTA _________$5$'
  4. $5$' _________ GATATG _________$3$'

    $3$'________CTACTA ________$5$'
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The sequence 5'-GAATTC-3' paired with 3'-CTTAAG-5' is the classic palindromic recognition site for the restriction enzyme EcoRI, which cuts between G and A.

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

Which of the following are all Nucleotides?

  1. Adenosine, Cytidylic acid, Cytosine

  2. Adenylic acid, Cytidylic acid, Guanylic acid

  3. Cytidine, Adenine, Adenylic acid

  4. Uracil, Thymidine, Thymidylic acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Nucleotides are compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA and RNA. For example, Adenylic acid, Guanylic acid, Thymidylic acid, and Cytidilic acid and 5'uridylic acid.
  • Hence Adenylic acid, Cytidilic acid, Guanylic acid are all Nucleotides.
  • So, the correct answer is 'Adenylic acid, Cytidilic acid, Guanylic acid'.
Multiple choice bio-chemistry applications of biotechnology pcr cutting, insertion and ligation of dna gene cloning procedure biotechnological regulations asexual modes of reproduction

Melting of DNA at 70$^o$ C is due to breakdown of

  1. Phosphodiester bonds

  2. Hydrogen bonds

  3. Glycosidic bonds

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

DNA denaturation involves the separation of the two strands of the double helix. This process is driven by the breaking of hydrogen bonds between complementary nitrogenous bases.

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

At which temperature a DNA molecule is denatured by heat in PCR

  1. 70$^o$ - 80$^o$C
  2. 90$^o$ - 95$^o$C
  3. 42$^o$C
  4. 50$^o$ - 65$^o$C
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the PCR process, the denaturation step requires high temperatures to break the hydrogen bonds between DNA strands. This typically occurs between 90 and 95 degrees Celsius.

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.