Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

The function of pineal body is to :

  • lighten the skin colours

  • control sexual behaviour

  • regulates the period of puberty

  • all of the above


D.

all of the above

The pineal body (gland) is small mass of tissues near the centre of the mammalian brain. It secretes the hormone melatonin. It contains light sensitive cells or has nervous connections from the eyes and melatonin regulates function related to light. It also regulates sexiial behaviour and regulating the period of puberty.


22.

DNA/chromosome replication takes place during:

  • G1- phase

  • G2- phase

  • S- phase

  • Prophase


C.

S- phase

Replication of DNA and synthesis of histone protein takes place during S- phase. At the end of S phase, each chromosome has two DNA molecules, i.e., a duplicate set of genes.


23.

Active transport occurs :

  • against concentration gradient and requires ATP

  • against concentration gradient and does not require ATP

  • along concentration gradient but require ATP

  • along concentration gradient but does not require ATP


A.

against concentration gradient and requires ATP

Active transport uses specific proteins called pumps, which use metabolic energy(ATP) to move ions or molecules against their concentration gradient. Common examples of active transport are Na+ - K+ ATPase. Ca++ ATPase and proton pump.


24.

Which of the following part of a neuron is covered by fatty sheath ?

  • axon

  • cyton

  • dendrite

  • node of Ranvier


A.

axon

Nerve fibres which conducts impulse away from the cell body are termed as axons. They are thinner than dendrites and may be several meter long. Axons consists of an axis slender (axoplasm), surrounded in most vertebrates by fatty myelin sheath.


25.

Principle protein of cillia and flagella is :

  • globulin

  • fibrin

  • flagellin

  • tubulin


D.

tubulin

Axoneme is the microtubular structure of cilia and falgella. The axoneme is composed of variety of proteins such as α and β tubulins dynein and nexin etc.


26.

Which of the following nerve is purely motor nerve?

  • vagus

  • facial

  • abducens

  • trigeminal


C.

abducens

Abducens is an example of a pure motor nerve. It arises from the anterior end of medulla oblongata in the vertebrate brain to supply the posterior rectus muscle of each eye ball.


27.

A fruit developed from a condensed inflorescence is :

  • simple fruit

  • aggregate fruit

  • composite fruit

  • etaerio


C.

composite fruit

Composite fruits are those fruits which develop from the entire inflorescence rather than from single flower. Eg, Sorosis and Syconus.


28.

Photosynthetic bacteria have :

  • pigment system I (only one pigment system)

  • pigment system II

  • both (a) and (b)

  • some other type


A.

pigment system I (only one pigment system)

PS I or photosystem I is present in photosynthetic bacteria. The photosynthetic pigments are located in the lamallae of thylacoid called chromatophores. The oxygen is not evolved in bacterial photosynthesis.


29.

The stage of cell cycle when cell has undergone differentiation is :

  • G0

  • G1

  • G3

  • G4


A.

G0

G0 is the phase which undergoes differentiation. It is also known as quiscent phase.


30.

The yellow colour of urine is due to the presence of

  • urea

  • uric acid

  • urochrome

  • bilirubin


C.

urochrome

Urochrome is a yellow coloured pigment in urine responsible for its yellow colour. It is derived from destruction of haemoglobin by reticuloendothelial cells.