Neural Control and Coordination

NEET Biology · 57 questions · Page 5 of 6 · Click an option or "Show Solution" to reveal answer

Q41

In which animal nerve cell is present but brain is absent?

A Sponge

B Earthworm

C Cockroach

D Hydra

Correct Answer

Option D

Solution

(d) A primitive type of nervous system, without brain is found in the form of intra epidermal nerve net in Hydra.

However, there is no brain in Hydra to coordinate the response.

Q42

Which of the following statements is correct for nodes of Ranvier of nerve?

A Neurilemma is discontinuous

B Myelin sheath is discontinuous

C Both neurilemma and myelin sheath are discontinuous

D Covered by myelin sheath

Correct Answer

Option B

Solution

(b) The myelin sheath is interrupted at the spaces between schwann cells to form gaps.

These gaps are called Nodes of Ranvier.

Q43

The Nissl granules of nerve cells are made up of

A ribosomes

B proteins

C DNA

D mitochondria

Correct Answer

Option A

Solution

(a) Prominent granules (Nissl granules) observed in the cytoplasm of the cyton are believed to be made of ribosomes.

Q44

In the resting state of the neural membrane, diffusion due to concentration gradients, if allowed, would drive

K^{+}

into the cell

K^{+}

and

Na^{+}

out of the cell

Na^{+}

into the cell

Na^{+}

out of the cell

Correct Answer

Option C

Solution

(c) In a resting state of the neural membrane, $Na^{+}$ concentration is higher on the outer side and $K^{+}$ concentration is more within the cell.

Hence if diffusion is allowed $Na^{+}$ would enter the cell and $K^{+}$ would leave.

Q45

Injury to vagus nerve in humans is not likely to affect

A tongue movements

B gastrointestinal movements

C pancreatic secretion

D cardiac movements

Correct Answer

Option A

Solution

(a) Muscles of the tongue are invested by the 12th cranial nerve, Hypoglossal.

The 10th cranial nerve, vagus supplies the viscera of the thorax, abdominal region and thus controls gastrointestinal, cardiac movements and pancreatic secretion.

Q46

One of the examples of the action of the autonomous nervous system is

A swallowing of food

B pupillary reflex

C peristalsis of the intestine

D knee-jerk response

Correct Answer

Option C

Solution

(c) Autonomic nervous system regulates and coordinates involuntary activities like heart beat, homeostasis, body temperature, breathing, gut peristalsis and secretion of glands.

Q47

In a man, abducens nerve is injured. Which one of the following functions will be affected?

A Movement of the eye ball

B Movement of the tongue

C Swallowing

D Movement of the neck

Correct Answer

Option A

Solution

(a) Abducens nerve is the sixth cranial nerve.

It innervates the extraocular muscle (superior oblique) of the eyeball, therefore controls movement of the eyeball.

Q48

Four healthy people in their twenties got involved in injuries resulting in damage and death of a few cells of the following. Which of the cells are least likely to be replaced by new cells?

A Liver cells

B Neurons

C Malpighian layer of the skin

D Osteocytes

Correct Answer

Option B

Solution

(b) The neurons are cells specialised to conduct an electrochemical current.

Neuron cells do not have the capability of division.

Q49

Which one of the following pairs of structures distinguishes a nerve cell from other types of cells?

A Vacuoles and fibres

B Flagellum and medullary sheath

C Nucleus and mitochondrion

D Perikaryon and dendrites.

Correct Answer

Option D

Solution

(d) The cytoplasm immediately surrounding the nucleus is loaded with protein synthetic machinery and is called perikaryon.

Dendrites are usually shorter, tapering and much branched processes.

These two are only present in nerve cells.

Q50

Nissl bodies are mainly composed of

A Proteins and lipids

B DNA and RNA

C Free ribosomes and RER

D Nucleic acids and SER

Correct Answer

Option C

Solution

When observed under electron microscope, they appear to be composed of rough endoplasmic reticulum (RER) and free ribosomes hence help in protein synthesis.

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