Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Which of the following statements is correct

  • Aspergillus niger is used for producing cyclosporin A.

  • Activated sludge is digested by aerobic bacteria to produce marsh gas.

  • Fleming, Chain & Florey were awarded with Nobel Prize for discovering penicillin. 

  • BOD is amount of oxygen produced by bacteria on decomposition.


C.

Fleming, Chain & Florey were awarded with Nobel Prize for discovering penicillin. 

Aspergillus niger is used for commercial and industrial production of certain chemicals like citric acid. Activated sludge is digested by anaerobic bacteria to produce marsh gas. BOD is amount of oxygen required by bacteria for decomposition.


12.

Which statement is correct regarding mosses

  • They have dominant and independent sporophyte.

  • Their antherozoids require water for fertilization.

  • Their archegonia produce many eggs.

  • Their antherozoids are multiflagellated


B.

Their antherozoids require water for fertilization.

In mosses the sporophytes (i.e. the diploid body) are short-lived and dependent on the gametophyte. In the presence of water, sperms from the antheridia swim to the archegonia and fertilization occurs, leading to the production of a diploid sporophyte. The sperm of mosses is biflagellate, i.e. they have two flagella that aid in propulsion. Since the sperms must swim to the archegonium, fertilization cannot occur without water.


13.

Which of the following statements is incorrect regarding fermentation

  • Propionibacterium is used to ferment the cheese.

  • The puffed-up appearance of dough is due to the production of CO2 gas.

  • Fermentation in muscle produces ethanol.

  • Toddy is made by fermenting sap from palms.


C.

Fermentation in muscle produces ethanol.

Fermentation in muscle produces lactic acid. In our bodies certain muscle cells, called fast twitch muscles, have less capability for storing and using oxygen than other muscles. When we run, these muscles run short of oxygen, the fast twitch muscles begin using lactic acid fermentation. This allows the muscle to continue to function by producing ATP by glycolysis.


14.

Assertion: Enzymes lower down the activation energy of the reactant molecule to make its transition into product easier.

Reason: Enzymes are highly substrate specific catalysts.

  • 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

Enzymes are highly substrate specific i.e. they catalyze the reaction of a particular substrate only. They facilitate occurrence of a reaction and transition of reactant into product.

A chemical reaction SP (where S is the substrate and P the product or products) will take place when a certain number of S molecules at any given instant possess enough energy to attain an activated condition called the 'transition state'. The enzyme combines transiently with the substrate to produce a transient state having a lower energy of activation than that of substrate alone. This results in acceleration of the reaction. Once the products are formed, the enzyme (or catalyst) is free or regenerated to combine with another molecule of the substrate and repeat the process.


15.

Which of the following elements is present in very less quantity in the body

  • K

  • Ca

  • Mg

  • Cu


D.

Cu

Trace elements or microelements (e.g. iron, iodine, zinc, manganese, cobalt, copper, molybdenum, etc.) are required in very small amounts to our body.


16.

Kingdom Animalia is characterised by

  • direct dependence on autotrophs

  • indirect dependence on autotrophs

  • absence of chlorophyll

  • absence of cell wall.


D.

absence of cell wall.

The main criteria for classification used by Whittaker includes cell structure, thallus organization, mode of nutrition, reproduction and phylogenetic relationships. So, the absence of cellwall  is one of the main characteristics of animal kingdom.


17.

Assertion: Movement of materials inside phloem is bidirectional i.e. it can be both upwards or downwards.

Reason: Movement of molecules inside xylem is unidirectional i.e. always upwards.

  • 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

Long distance bulk movement of substances that occurs through conducting or vascular tissues of plants is called translocation. There are two vascular tissues, xylem and phloem. Xylem translocation is mainly from roots to aerial parts. It passes water with mineral salts, some organic nitrogen and hormones i.e. unidirectional. Phloem translocates organic substances and inorganic solutes first from leaves to all other parts of the plant and storage organs. Storage organs re-export organic nutrients to those parts which require the same as newly formed leaves and fruits i.e. it is bidirectional.


18.

Assertion: Water that enters into a plant cell through diffusion makes it turgid.

Reason: Entry of water into the cell through diffusion develops wall pressure inside the cell.

  • 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

Cell's turgidity is due to turgor pressure. Turgor pressure is the pressure which develops in the confined part of an osmotic system due to osmotic entry of water into it. It is also called hydrostatic pressure or pressure potential. The force exerted by the cell wall over the protoplast is called wall pressure. Normally wall pressure is equal and opposite to turgor pressure except when the cell becomes flaccid.


19.

Which of the following statements is correct

  • Photorespiration is useful process.

  • C4 plants are more efficient than C3 plants.

  • C3 plants are more efficient than C4 plants.

  • Photorespiration is absent in C3 plants but present in C4 plants.


B.

C4 plants are more efficient than C3 plants.

C4 plants are more efficient than C3 plants because they have little photorespiration while in C3 plants more than half of photosynthetic carbon get lost in photorespiration. C4 plants are more efficient in picking up CO2 even in low CO2 concentration because of high affinity of CO2 with PEP (phosphoenol pyruvic acid).


20.

Which of the following is not a characteristic of meiosis

  • It involves two stages of DNA replication one before meiosis-I and another before meiosis-II

  • It involves recombination and crossing over

  • Sister chromatids separate during anaphase II

  • Nuclear membrane disappears during prophase.


A.

It involves two stages of DNA replication one before meiosis-I and another before meiosis-II

Chromosome replication occurs once but meiosis has two M-phases each with its own karyokinesis and cytokinesis. As a result chromosome number is halved. The transition period between M-phase I (meiosis I) and M-phase II (meiosis II) is short and without DNA replication. It is called interkinesis.