Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

31.

Starch is insoluble in water, yet it is accumulated in large quantities in potato tuber because :

  • it is useful for storage

  • tubers respire slowly

  • starch is synthesized in tubers

  • translocated sucrose is polymerized here


A.

it is useful for storage

Starch is insoluble in water, yet it is accumulated in large quantities in potato tuber because, it is useful for storage.


32.

Which of the following is not a co-enzyme?

  • NAD

  • NADP

  • FAD

  • ATP


D.

ATP

Co-enzymes are organic molecules that acts as co-factors, but unlike prosthetic groups they do not remain attached to the enzyme between reaction. NAD, NADP and FAD are co-enzymes whereas ATP is an energy carrier in cell.


33.

In case of C4 plants the acceptor of CO2 is-

  • Phosphoglyceraldehyde

  • Ribulose monophosphate

  • Phosphoenol pyruvate

  • Ribulose diphosphate


C.

Phosphoenol pyruvate

In C4 plants, CO2 is accepted by Phosphoenol pyruvate or PEP. PEP carboxylase catalyses the recation that converts PEP + CO2 into oxaloacetate. Eg, Sugarcane, maize, SorghumAmaranthus etc.

PEP + CO2 PEPcarboxylaseOxaloacetate


34.

A bryophyte which harbours a nitrogen fixing blue-green alga in its thallus is :

  • Pogonatum

  • Riccia

  • Marchantia

  • Anthoceros


D.

Anthoceros

A nitrogen fixing blue-green algae Nostoc is found inhabited in the mucilage cavity of Anthoceros. Nostoc Anthoceros association is a highly specialized form of symbiosis in which both the partners are mutually beneficial to each other. Nostoc provide nitrogen to the Anthoceros and Anthoceros provide place to live for Nostoc.


35.

Gymnosperms are called naked seed plants because these lack :

  • cotyledon

  • endosperm

  • ovary wall

  • testa


C.

ovary wall

Gymnosperms are commonly called as naked seed plants. This is because they are not covered by ovary wall. Ovules lie naked on the surface of megasporophylls which are arranged into cones.


36.

The first step in dark reaction of photosynthesis is :

  • formation of ATP

  • ionization of water

  • attachment of CO2 to a pentose sugar

  • excitement of electron of chlorophyll by a photon of light


C.

attachment of CO2 to a pentose sugar

The first step in dark reaction of photosynthesis is carboxylation in which three molecules of CO2 combine with three molecules of ribulose 1, 5-biphosphate (RuBP) to form unstable six carbon compound. Carboxylation of RuBP is catalysed by the enzyme RuBP carboxylase or Rubisco.


37.

The circinate vemation is the characteristic feature of ferns. It refers to :

  • coiling of young leaves

  • arrangement of leaves on stem

  • attachment of sori on leaves

  • heterophilly


A.

coiling of young leaves

The fern leaf, differs from the true leaf (euphyll) of the flowering plants in its vernation, or manner of expanding from the bud. In most ferns, vernation is circinate; that is, the leaf unrolls from the tip, with the appearance of a fiddlehead, rather than expanding from a folded condition. Vernation refers to the growing of a new leaf; circinate refers to the arrangement of the leaf, which is  circular.


38.

Good soil is :

  • which holds whole of the water that enters into it

  • which allows percolating the water slowly from it

  • which allows water to pass very quickly from it

  • which allows limited amount of water to retain into it


B.

which allows percolating the water slowly from it

Good soil is a soil which allows percolating the water slowly from it. Minerals, air, water and organic matter are essential for maintaining a good soil structure that enables adequate air exchange and water drainage. Eg, alluvial soil.


39.

A metal ion involved in stomatal regulation is :

  • iron

  • potassium

  • zinc

  • magnesium


B.

potassium

Potassium ions are involved in the stomatal movement. Alongwith negative ions, K+ ions accumulate in guard cells in response to light. Solute potential become more negative, resulting in entry of water by osmosis and the turgid guard cells. Therefore, the turgidity of guard cell open the stomata.


40.

Chiasmata are most appropriately observed in meiosis during :

  • diakinesis

  • diplotene

  • metaphase II

  • pachytene


B.

diplotene

Chiasmata is observed in meiosis during diplotene, sub stage of Prophase-I. It is the result of crossing over. Each chiasmata is the site of an exchange between chromatids. It is produced by breakage and reunion between any two of the four strands present at each site.