NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions


From which of the following, photosynthetic autotrophs receive their energy?

  • Heat

  • Inorganic chemicals

  • Organic chemicals

  • Light



Photosynthesis is the synthesis of organic compounds (primarily sugars) from carbon dioxide (CO2) and water using light energy. The green cells of the plant convert the solar energy into chemical energy through this process. It's importance lies in the transformation of low energy compounds ie, CO2 and H2O into high energy compounds such as carbohydrates.


In floral formula (K) denotes

  • polysepalous

  • gamosepalous

  • polypetalous

  • gamopetalous



In floral formula, (K) denotes polysepalous condition. When the sepals of a flower are free from each other the condition is called polysepalous and if they are fused with each other, the condition is known as gamosepalous.

Polypetalous is a flower in which the corolla consists of seperate petals.

Gametopetalous is a flower in which the petals are fused to form a corolla tube.


When does a plant wilt?

  • When phloem is blocked

  • When xylem is blocked

  • Pith is removed

  • A few leaves are removed


When xylem is blocked

Wilting is the loss of turgidity of leaves and other soft aerial parts of a plant causing their drooping, folding and rolling. It is caused by blocking of xylem.


Which chemical is used for induction of polyploidy?

  • Cytokinin

  • Nitrous acid

  • Colchicine

  • IAA



Colchicine is an alkaloid obtained from the plant. Colchicum autumnale and is found to prevent the formation and organization of spindle fibres. It induces polyploidy in many plant and animal cells.


In the following pairs, where do you get lignin in both the element?

  • Tracheid and collenchyma

  • Sclerenchyma and sieve tube

  • Sclerenchyma and trachea

  • Parenchyma and endodermis


Sclerenchyma and trachea

The cells of sclerenchyma are long or short, narrow, thick walled and lignified. These are dead cells and do not perform any metabolic function. Tracheids (tracheary element) are elongated cells with tapering ends. The wall of tracheids is moderatly thick and usually lignified.


Which of the following sequence is a correct one for meiotic cell cycle?

  • GS G M G1

  • G1 G2 G2

  • G2 G1 G2

  • G1 G2 S



The basic parts of cell cycle are interphase and M-phase or dividing phase. The interphase is metabolically the most active stage and divided into G1, S and G2 phases. The correct sequence of phases in cell cycle is

G1 G2 G1


Which of the following is photophosphorylation?

  • Production of ATP from ADP

  • Production of NADP

  • Synthesis of ADP from ATP

  • Production of PGA


Production of ATP from ADP

Photophosphorylation is the synthesis of ATP from ADP during light reaction of photosynthesis. It was discovered by Amon et al, in 1954.


In guava, cucurbits flowers are

  • hypogynous

  • epigynous

  • perigynous

  • Both (a) and (c)



In an epigynous flower, the innermost whorl, ie, gynoecium is covered by the elongated margins of thalamus thus, their position is inferior in regard to other floral whorls, which arise above the ovary and thus superior, eg, sunflower, Cucurbita, coriander.


What is the structural element of cell wall?

  • Matrix

  • Microtubules

  • Microfibrils

  • Arabinogalactans



The cell wall contains a porous matrix of cellulose consisting of vary fine coalesced fibrils the microfibrils and an interfibrillar system of microcapillaries containing various non-cellulosic wall constituents.


In which book, Bentham and Hooker proposed their classification?

  • Genera Plantarum

  • Species Plantarum

  • Historia Plantarum

  • Historia Naturae


Genera Plantarum

Bentham and Hooker published natural system of classification in their Genera Plantarum. This system was based on arrangement of leaves and venation pattern, number of members in floral whorls, cohesion of various floral organs, number of cotyledons and presence or absence of cover around the seeds.