NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions


The map distance between the genes A and B is 3 units, between B and C is 10 units and between C and A is 7 units. The order of the genes in a linkage map constructed on the above data would perhaps be

  • A, B, C 

  • A, C, B

  • B, C, A

  • B, A, C


B, A, C

From the recombination frequencies between different genes A, B and C, it is clear that distance between A and B genes is 3 units between B and C is 10 units and C and A is 7 units. Hence, linear order of genes on chromosomes is


sprouting of potato can be prevented in storage by

  • maleic hydrazide

  • gibberellins

  • indole acetic acid

  • cytokinins


maleic hydrazide

alpha chloronaphthalene, methyl ester of alpha naphthalene-acetic acid (MENA) and maleic hydrazide (MH) applied in wax or water in inhibiting sprouting or potatoes during the latter part of the late-crop shipping season.


Lichens are important in the studies on atmospheric pollution because they

  • can grow in polluted atmosphere

  • can readily multiply in polluted atmosphere

  • efficiently purify the atmosphere

  • are very sensitive to pollutants like sulphur dioxide


are very sensitive to pollutants like sulphur dioxide

Lichens are extremely sensitive to SO2 an could be regarded as indicator of SOpollution.


In the lactose operon of Escherichia coli what is the function of promoter

  • Binding of Gyrase enzyme

  • Binding of RNA polymerase

  • Codes for RNA polymerase

  • Processing of messenger RNA


Binding of RNA polymerase

Promoters contain specific DNA sequences such as response elements that provide a secure initial binding site for RNA polymerase and for proteins called transcription factors that recruit RNA polymerase.


The pyramid of energy-in a forest ecosystem is

  • always upright

  • always inverted

  • both (a) and (b)

  • none of the above


always upright

In a forest ecosystem, the producers are large size trees which make the base of Pyramid. The herbivores such as fruit eating birds, deer, elephants etc. make the primary consumers and are less than primary producers. After that, the number goes down at each successive level.


Sex factor in bacteria is

  • F-replicon

  • chromosomal replicon

  • RNA

  • sex pillies



In bacteria, besides nuclear DNA, there is some extrachromosomal or extranuclear DNA which is known as plasmid. Term plasmid was given by Lederberg (1952). On the basis of their function, the plasmids are of 3 types :

(i) F or fertility factor : Responsible for transfer of genetic material

(ii) R or resistance factor Provides resistance against drugs.

(iii) Colicinogenic factor : Provides colicines which kill other bacteria (other than which produce these colicines).


One of the following is sex-influenced character

  • Appearance of beard

  • Baldness in male

  • Docile behaviour of female

  • Low BMR in female


Baldness in male


Low BMR in female

Inheritance of pattern baldness in man is an example of sex-influenced trait which is dominant in males and recessive in females.


Embryo sac is

  • microgametophyte

  • microsporangium

  • megagametophyte

  • megasporangium



Meibomian glands are also called tarsal glands and are modified sebaceous gland on the edges of eyelids, these keep a thin film of oil over the cornea which acts as lubricant.


9: 3: 3: 1 ratio is modified to 9 : 7 ratio due to

  • complementary gene

  • epistatic gene

  • hypostatic gene

  • supplementary gene


complementary gene

Complementary genes are the genes which are present on different genetic loci but interact with each other to express a single character in combination. That is they both together produce a particular phenotypic trait in an individual. Supplementary genes are the genes which include two pairs of non-allelic genes.


Polymerase chain reaction is most useful in

  • DNA synthesis

  • DNA amplification

  • protein synthesis

  • amino acid synthesis


DNA synthesis

Polymerase chain reaction (PCR) is a method widely used in molecular biology to make many copies of a specific DNA segment. Using PCR, a single copy (or more) of a DNA sequence is exponentially amplified to generate thousands to millions of more copies of that particular DNA segment