Biology

DNA and Genetics

985 Questions

DNA and genetics questions explore molecular biology, DNA replication, and genetic engineering techniques. These topics are essential for various competitive exams requiring a strong foundation in life sciences. Practice these questions to understand complex biological processes thoroughly.

DNA replication mechanismsGenetic engineering techniquesGene editing toolsPolymerase chain reactionDNA sequencing methods

DNA and Genetics Questions

Multiple choice zoology molecular basis of inheritance the search for genetic material dna structure and replication molecular genetics

In Griffiths experiment, the conversion of R- type to S-type of Diplococcus pneumoniae when mixed with heat-killed S-type is called

  1. Mutation

  2. Transduction

  3. Transfection

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

Transformation is the process by which bacteria take up naked DNA from their environment, as demonstrated by Griffith's experiment with S and R strains of Streptococcus pneumoniae.

Multiple choice zoology molecular basis of inheritance the search for genetic material dna structure and replication molecular genetics

Which of the following is true with reference to transformation in bacteria
i) Transfer of genetic material is mediated by F factor
ii) Uptake of DNA fragments from the surrounding environment and expression of that genetic information in recipient cell 
iii) Transformation experiments were the basis to propose chromosomal theory of inheritance
iv) Transformation was discovered by Griffith in Streptococcus pneumonia

  1. i, iv

  2. ii, iii, iv

  3. iii, iv

  4. ii, iv
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Statement ii is correct (definition of transformation) and iv is correct (Griffith's discovery). Statement i refers to conjugation, and iii is historically incorrect as transformation was not the basis for the chromosomal theory of inheritance.

Multiple choice zoology molecular basis of inheritance the search for genetic material dna structure and replication molecular genetics

Escherichia coli in which both the strands are labelled with $^{15}N$ is transferred to $^{14}N$ medium and allowed to replicate for two generations. Find the number of hybrid DNA molecules in the second generation

  1. Four

  2. Eight

  3. One

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

In semi-conservative replication, after one generation, all DNA is hybrid. After two generations, half the DNA is hybrid and half is light (14N-14N). Starting with one 15N-15N molecule, after two generations, you have four molecules: two hybrid (15N-14N) and two light (14N-14N).

Multiple choice botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

Mendel formulated the law of purity of gametes on the basis of _______________

  1. Dihybrid cross

  2. Monohybrid cross

  3. Back cross

  4. Test cross
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • The monohybrid cross-refers to inheritance of singe contrasting trait by two parents at a time. For example, a cross of tall (T) and dwarf (t) pea plants (TT x tt). Mendel observed that monohybrid cross between two pure breeding varieties yields $F _1$ generation which exhibits the dominant trait; although factor for a recessive trait is present in $F _1$ hybrids. Self-fertilization of $F _1$ generation obtains $F _2$ generation which exhibits both dominant and recessive traits in the 3:1 phenotypic ratio. This laid the foundation of the law of purity of gametes which states that the two factors for a trait, present together in a heterozygous individual, do not get mixed and are separated during gametogenesis. 
Multiple choice botany mendel's law of inheritance genetics terminology similarities and dissimilarities in organisms introduction to genetics features of human body and sign language

A husband and wife have normal vision but fathers of both of them were colour blind. Probability of their first daughter to be colour blind is

  1. 25%

  2. 50%

  3. 75%

  4. 0%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Probability of their first (or any) daughter being colourblind is nil as the daughter of normal father can never be colourblind.

Multiple choice biology the life cycle of animals how do animals reproduce? excretory, nervous and reproductive system structure and functions of living organisms -ii

A mixture containing DNA fragments a, b, c and d with molecular weights of a+b = c, a > b and d > c, was subjected to agarose gel electrophoresis. The movement of these fragments from cathode to anode sides of the gel would be

  1. Smaller molecules move faster

  2. Both smaller and larger will move at same pace

  3. Larger will move faster

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • In Agarose gel electrophoresis we separate macromolecules like DNA, RNA and protein on the basis of their molecular size and charge.
  • In this Shorter molecules move faster and migrate farther than longer ones because shorter molecules migrate more easily through the pores of the gel. 
  • DNA migrate towards anode.
Multiple choice botany option b: biotechnology and bioinformatics dna transfer rdna technology - dna transfer and transformation biotechnology in agriculture

Transfer of DNA bands from agarose gel to nitrocellulose or nylon membrane is

  1. Southern transfer

  2. Western transfer

  3. Northern transfer

  4. Eastern transfer

  5. Gene transfer
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Southern blotting is the technique used to transfer DNA fragments from an agarose gel to a membrane (like nitrocellulose) for hybridization analysis.

Multiple choice botany option b: biotechnology and bioinformatics dna transfer rdna technology - dna transfer and transformation biotechnology in agriculture

The technique in which foreign DNA is precipitated over surface of metal particles for passing into target cells is __________.

  1. Microinjection

  2. Electroporation

  3. Particle gun

  4. Chemical mediated gene transfer
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Particle gun technology, also known as biolistics, involves coating microscopic metal particles (like gold or tungsten) with DNA and accelerating them into target cells. This physical method is distinct from chemical or electrical gene transfer techniques.

Multiple choice botany option b: biotechnology and bioinformatics dna transfer rdna technology - dna transfer and transformation biotechnology in agriculture

Microparticles for coating with DNA to be bombarded with gene gun are made of

  1. Silver or platinum

  2. Platinum or zinc

  3. Silicon or platinum

  4. Gold or tungsten
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Gold and tungsten are the standard materials used for microprojectiles in biolistic gene transfer because they are inert, dense, and can be easily prepared as microparticles.

Multiple choice botany biotechnology: general introduction microbiology: organisms in industry biotechnology commercial applications of biotechnology

Recombinant DNA research uses mostly prokaryotic bacteria and eukaryotic ............... as recipient cells because of their fast reproduction in laboratory conditions.

  1. E. coli

  2. Drosophila

  3. Yeasts

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

The basic process of recombinant DNA technology revolves around the activity of DNA in the synthesis of protein. By intervening in this process, scientists can change the nature of the DNA and of the gene make-up of an organism. By inserting genes into the genome of an organism, the scientist can induce the organism to produce a protein it does not normally produce. The genes used in DNA technology are commonly obtained from host cells or organisms called as gene libraries. A gene library is a collection of cells identified as harbouring a specific gene. For example, E. coli cells can be stored with the genes for human insulin in their chromosomes. Vaccines represent another application of recombinant DNA technology. For instance, the hepatitis B vaccine now in use is composed of viral protein manufactured by yeast cells, which have been recombined with viral genes. 

Multiple choice biomacromolecules biotechnology cell biology and biotechnology biomolecules biology

Identify the correct order of the size of the structures from the smallest to the largest.
I= Bacterium
II= Enzyme
III= Nucleus
IV= Chromosome
V= Molecule of water

  1. V- II- I- IV- III

  2. II- V- IV- I- III

  3. V- I- II- III- IV

  4. II- V- I- IV- III

  5. II-V-IV-III
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A water molecule has two hydrogen and one oxygen atom and is smallest among the given options. An enzyme can be as small as a chain of 60 amino acid residues, while a bacterium ranges in 1 micrometre in diameter. The chromosome contains linear DNA molecule which is 2 m long. Nucleus diameter is  6 micrometers. The correct ascending order of size is water molecule, enzyme, bacterium, chromosome and nucleus. 

So, the correct answer is option A.

Multiple choice biology reproduction in organisms sexual reproduction in organisms sexual reproduction & its importance modes of reproduction

Bacterial recombination mediated by certain external non-cellular, nucleoprotein entities is

  1. Conjugation

  2. Transformation

  3. Sexduction

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

  • Conjugation is merely the fusion of two compatible bacterial cells. Bringing two genotypes together and allowing them to conjugate is the equivalent of making a cross in eukaryotes.
  • Our discussion of conjugation will center on the gut bacterium Escherichia coli ($E$. coli). Conjugation and gene transfer in $E$. coli are driven by a circular $DNA$ plasmids called the fertility factor or sex factor $(F)$, which is found in some but not all cells. Hence to understand how to make a cross in $E$. coli, we have to understand the properties of $F$.

Multiple choice bio-chemistry biochemical techniques manipulation of dna electrophoresis isolation and separation of dna

Gel electrophoresis is a

  1. Technique of separation of charged molecules under the influence of magnetic field

  2. Technique of incorporation of DNA molecules into the cell through transient pores made due to electrical impulses

  3. Technique of separation of DNA fragments through the pores of agarose gel under the influence of electric field

  4. Technique of separation and purification of gene products
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Electrophoresis is a technique of separation of molecules such as DNA, RNA or protein, under the influence of an electrical field, so that they migrate in the direction of electrode bearing the opposite charge, viz. positively charged molecules move towards cathode (-ve electrode) and negatively charged molecules travel towards anode (+ve electrode) through a medium/matrix. Since DNA fragments are negatively charged molecules, they can be separated by allowing them to move towards the anode (+ve electrode) under an electric field through a matrix of agarose gel.
So, the correct answer is 'Technique of separation of DNA fragments through the pores of agarose gel under the influence of electric field'.