Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

In photosynthesis carbon dioxide is converted to carbohydrates. It is a process.

  • Reductive

  • Oxidative

  • Catabolic and exergonic

  • None of the above


A.

Reductive

Photosynthesis is an oxidation reduction process in which water is oxidised  and carbon dioxide is reduced to carbohydrates. Hence, it is an anabolic and endergonic process.


22.

Which of the following characteristics is are exhibited by C4 -plants?

I. Kranz anatomy.
II. The first product of photosynthesis is oxaloacetic acid.
III. Both PEP carboxylates and ribulose biphosphate carboxylate act as carboxylating enzymes.

The correct option is

  • I and III, but not ll

  • I and II, but not III

  • II and III, but not I

  • ll and III


C.

II and III, but not I

C-4 plants have an alternative CO2 fixation pathway called Hatch and Slack cycle. These plants have Kranz anatomy in leaf, where vascular bundles are surrounded by bundle sheath.


23.

Genetic dwarfism can be overcome by

  • Gibberellin

  • Ethylene

  • Auxin

  • ABA


A.

Gibberellin

Genetic dwarfism is overcome by the usage of gibberellins. Ethylene is a gaseous hormone, which induces ripening in unripe fruits. ABA cause ageing and abscission of leaves.


24.

Hormone inducing fruit ripening is

  • Cytokinin

  • Ethylene

  • Aabscissic acid

  • Gibberellic acid


B.

Ethylene

Ethylene is a natural gaseous hormone, which is predominantly known for inducing fruit ripening.


25.

Which of the following properties is shown by cytokinins?

  • Delay leaf senescence

  • Cause leaf abscission

  • Promote seed dormancy

  • Promote stornatal closing


B.

Cause leaf abscission

Cytokinin is a plant growth hormone, which is mostly synthesised in the roots. Cytokinin delays leaf senescence.


26.

Given below is a schematic break-up of the phases/stages of cell cycle. Which one of the following is the correct indication of the stage/ phase in the cell cycle?

  • C-karyokinesis

  • S-synthetic phase

  • A-cytokinesis

  • B-metaphase


B.

S-synthetic phase

In cell cycle, there are two main phases-interphase and mitotic phase. Interphase is divided into three stage G1, S and G2, G1 is the first growth phase. S is a synthetic phase and G2 is second growth phase.


27.

Which of the following is not an auxin?

  • IM

  • IBA

  • Zeatin

  • NM


C.

Zeatin

Zeatin is a cytokinin. IAA or indole acetic acid is a natural auxin. IBA or indole butyric acid and NAA or naphthalene acetic acid are synthetic auxins.


28.

Which one of the following structural formula of two organic compounds is correctly identified along with its related function?

  • B-uracil – a component of DNA

  • A-triglyceride – major source of energy

  • A-lecithin – a component of cell membrane

  • B-adenine – a nucleotide that makes up nucleic


C.

A-lecithin – a component of cell membrane


29.

Which one out of (a) to (d) given below correctly represents the structural formula of the basic amino acid?


D.

Basic amino acids have an additional amino group with forming amides thus, they are diaminomonocarboxylic acids, e.g., lysine arginine, etc.


30.

Which of the following plant keeps its stomata open during night and closed during the day?

  • Orchid

  • Cactus

  • Tea

  • Wheat


A.

Orchid

Scotoactive mechanism of opening of stomata is seen in fleshy xerophytes like opuntia, cactus, etc. They keep their stomata open at night and closed during daytimes.