Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

51.

Assertion : Inbreeding produces pureline.

Reason : It causes homozygosity.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


A.

If both assertion and reason are true and reason is the correct explanation of assertion

Inbreeding refers to the mating of closely related individuals within the same breed for 4­ - 6 generations. Superior males and superior females of the same breed are identified and mated in pairs. The progeny obtained from such matings are evaluated and superior males and females among them are identified for further mating. Inbreeding increases homozygosity. Thus inbreeding is necessary if we want to evolve a pureline in any animal.


52.

Assertion : All pathogens are parasites but all parasites are not pathogens.

Reason : Majority of the parasites confer benefits to the host.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false


C.

If assertion is true but reason is false

Parasitism is a relationship between two living organisms of different species in which one organism called parasite obtains its food directly from another living organism called host. Majority of the parasites harm the host; they may reduce the survival, growth and reproduction of the host and reduce its population density. Pathogens are disease-causing microorganisms which get benefit by causing harm to host organism. Pathogens such as viruses, bacteria, fungi, protozoans, helminths, insects etc., reproduce or multiply inside the host organism and therefore, they get the opportunity to complete the life cycle and spread their population.


53.

Which of the following is correct regarding HIV, hepatitis B, gonorrhoea, trichomoniasis?

  • Trichomoniasis is a STD whereas other are not

  • Gonorrhoea is a viral disease whereas others are bacterial

  • HIV is a pathogen whereas others are diseases

  • Hepatitis B is eradicated completely whereas others are not


C.

HIV is a pathogen whereas others are diseases

HIV or Human Immunodeficiency Virus is a lentivirus that causes HIV infection and leads to AIDS.

Hepatitis B is an infection of liver. It causes scarring of the organ, liver failure and cancer.

Gonorrhoea is a sexually transmitted infection (STI) caused by bacteria called Neisseria gonorrhoeae or gonococcus. 

Trichomoniasis is also a sexually transmitted disease. It is caused by infection with a protozoan paraite called Trichomonas vaginalis.


54.

Assertion : Presence of large amounts of nutrients in water body causes excessive growth of planktonic algae.

Reason : It is due to biomagnification.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


C.

If assertion is true but reason is false

Presence of large amounts of nutrients in water causes excessive growth of planktonic algae or free- floating algae. It is known as algal bloom as it imparts a unique colour to the water bodies. Algal bloom cause deterioration of the quality of water and fish mortality. 

Biomagnification is the process by which a compound such as pollutant or pesticide increases its concentration in the tissues of organisms as it travels up the food chain.


55.

Assertion : Commelina shows cleistogamy.

Reason : This reduces chances of inbreeding.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


C.

If assertion is true but reason is false

Commenlia produce two types of flowers- 

(i) Chasmogamous: These flowers are similar to flowers of other species with exposed anthers and stigma.

(ii) Cleistogamous: These flowers do not open at all. In these flowers, anther and stigmalie close to each other. When anther dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, cleistogamous are invariably autogamous as there is no chance of cross- pollen landing on the stigma. 


56.

Assertion : Parturition is induced by neural signal in maternal pituitary.

Reason : At the end of gestation period, the maternal pituitary release prolactin which causes uterine contractions.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false


D.

If both assertion and reason are false

Parturition is the process of delivery of the foetus. It is induced by a complex neuroendocrine mechanism. The signals for parturition originates from the foetus and the placenta which induces mild uterine contractions called foetal ejection reflex. It triggers release of oxytocin from the maternal pituitary. Oxytocin acts on the uterine muscle and causes stronger uterine contractions, which in turn stimulates further secretion of oxytocin. The stimulatory reflex between the uterine contraction and oxytocin secretion continues resulting in stronger and stronger contractions. This leads to expulsion of the baby out of the uterus through the birth canal.


57.

Assertion : DNA fingerprinting involves identifying differences in specific regions in DNA sequence.

Reason : DNA fingerprinting is the basis of paternity testing.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


B.

If both assertion and reason are true but reason is not the correct explanation of assertion.

DNA fingerprinting involves identifying differences in some specific regions in DNA sequence called as repetitive DNA, as there is a small stretch of DNA which is repeated many times. These do not code for any proteins, but they form a large portion of human genome. These sequence show high degree of polymorphism and form the basis of DNA fingerprinting. As the polymorphisms are inheritable from parents to children, DNA fingerprinting is the basis of paternity testing in case of disputes.


58.

Assertion : Interferons are antiviral proteins.

Reason : Interferons are secreted by virus infected cells.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false


A.

If both assertion and reason are true and reason is the correct explanation of assertion.

Interferons or IFNs are a group of soluble glycoproteins that are produced and released from cells in response to virus infection. In humans, there are three types of interferons:

1. α- interferons

2. β- interferons

3. γ- interferons


59.

Recombinant DNA technology involves several steps in which initial step is of isolation of the DNA. Which enzymes are used in the process for the breakdown of fungal cell, plant cell and bacterial cell respectively?

  • Lysozyme, lipases, trypsin

  • Chitinase, cellulase, lysozyme

  • Chitinase, cellulase, trypsin

  • Trypsin, lipases, cellulase


B.

Chitinase, cellulase, lysozyme

Process of RDT or Recombinant DNA Technology involves isolation of DNA of a desired DNA fragment. The DNA should be in pure form, free form other macro- molecules. 

The bacterial cell or plant or an animal tissue is treated with enzyme lysozyme or cellulase or chitinase (fungal) enzyme respectively in order to break the cell to release DNA. RNA can be removed by treated the cell with ribonuclease and proteins can be removed by treatment with protease.


60.

Assertion : Antirrhinum is a good example to understand incomplete dominance.

Reason : Heterozygotes show characteristics of both the alleles.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


C.

If assertion is true but reason is false

Incomplete dominace is a form of intermediate inheritance in which one allele of a specific trait is not completely expressed over its paired allele.

Eg, Inheritance of flower colour in Antirrhinum.

There are two types of flower colour in pure state, red and white. When the two types of plants are crossed, the hybrid or plants of F1 generation have pink flowers. The pink colour apparently appears due to mixing of red and white colours.

Parent generation-    RR (Red)     ×    rr (White)

Gametes-                      R                   r

F1 generation-                        Rr (Pink)

F2 generation-               Rr          ×     Rr

Gametes-                     RR (Red) : Rr (Pink) : Rr (Pink) : rr (White)

Phenotypic ratio- Red : Pink : White

                              1   :    2   :   1

Genotypic ratio- RR : Rr : rr

                            1  :  2  : 1