NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions


Mutualism is found in

  • hermit crab and sea anemone

  • ox pecker and rhinoceros

  • zoochlorellae and Hydra

  • E.coli and man


zoochlorellae and Hydra

Mutualism is the ecological interaction between two or more species where each species benefits.

The unicellular photosynthetic algae, called Zoochlorella live symbiotically in the outer tissues of coelenterates. Algae are photosynthetic and produce oxygen and food beneficial to hosts and in exchange, they obtain materials like carbon- dioxide and nitrogenous wastes released by metabolism of host animals.


In prokaryotes, genetic recombination can occur during

  • transduction

  • transformation

  • conjugation

  • all of these


all of these

In prokaryotes meiosis is absent due to absence of gamete formation.  But genetic recombination occurs through following process:

(i) Transduction

(ii) Transformation

(iii) Conjugation.


During formation of which of the following free nuclear division occurs?

  • Flower

  • Endosperm

  • Gametes

  • Fruit



In nuclear endosperm the primary endosperm nucleus divides repeatedly without wall formation producing a large number of free nuclei. It is most common type of endosperm.


Chloromycetin is obtained from

  • Streptomyces venezuelae

  • Streptomyces rimosus

  • Bacillus subtilis

  • Clostridium botulinum


Streptomyces venezuelae

Chloromycetin or chloramphenicol is obtained from Streptomyces venezuelae.


An oocyte is released from the ovary under the influence of LH 

  • after completing meiosis and before polar bodies are released

  • after completing meiosis I and before release of polar bodies

  • after completing meiosis

  • after completing meiosis I and after release of polar bodies.


after completing meiosis I and before release of polar bodies

Graafian follicle develops under influence of FSH of anterior pituitary.  Its follicular cells secrete estrogen. Rising level of estrogen decreases production of FSH, and stimulates secretion of LH. The two cause mature Graafian follicle to release the ovum.


Which is Indian dwarf wheat?

  • T. dicoccum

  • T. sphaerococcum

  • T. turgidum

  • T. aestivum


T. sphaerococcum

Triticum aestivum is an Indian dwarf wheat. It is endemic to Southern Pakistan and North- western India.


Extranuclear genes occurs in

  • plastids and are not inherited

  • plasmid and are not inherited

  • mitochondria and are inherited by female

  • mitochondria and are inherited by male


mitochondria and are inherited by female

Cytoplasmic inheritance or non- chromosomal inheritance is the passage of traits from parents to offspring through structures present inside cytoplasm of contributing gametes. Genes controlling cytoplasmic inheritance are called plasma genes or extra nuclear genes. They occur in plastids, mitochondria, plasmids. It is usually uniparental. Also, it is known as maternal inheritsnce.


Assertion : Watson and Crick provided experimental proof of semiconservative nature of DNA replication.

Reason : DNA polymerase binds nucleotides in replication.

  • If both Assertion and Reason are true and Reason is the correct explantion of Assertion

  • If both Assertion and Reason are true and Reason is not the correct explanation of Assertion

  • If Assertion is true but Reason is false

  • If Assertion is false but Reason is true.


If Assertion is false but Reason is true.

Watson and Crick suggested the double helical structure of DNA. Semiconservative nature of DNA replication was proved by Messelson and Stahl by using heavy isotope of nitrogen (15N).

DNA polymerase III establishes phosphodiester linkages between the adjacent deoxyribo-nucleoside phosphate in presence of ATP/GTP, TPP and Mg2+. It produces a new strand of DNA. DNA polymerase binds nucleotides in 5'-3' direction.


Which of the following pesticides is an acetylcholinesterase inhibitor?

  • Aldrin

  • BHC

  • Endosulfan

  • Malathion



Organophosphate or Malathion kills insects by inhibiting enzyme cholinesterase. It is an organic ester of carbonic acid. Its structure is somewhat similar to acetylcholine and, therefore has strong affinity for the enzyme acetylcholinesterase, and inhibits its activity.


The sphere of living matter together with water, air and soil on the surface of earth is called

  • atmosphere

  • hydrosphere

  • lithosphere

  • biosphere



Biosphere is the biologically inhabited part of earth along with its abiotic or physiochemical components. It consists of three sub- divisions, namely, atmosphere, lithosphere and hydrosphere.

(i) Atmosphere refers to the transparent gaseous mantle surrounding the earth.

(ii) Lithosphere refers to the outer solid crust of earth.

(iii) Hydrosphere is liquid mantle of earth.