Control and coordination short answer question 1

1. Define a synapse.

Synapse is a very fine gap between telodendria of axon of one neuron and dendrites of another neuron. These two structures do not unite with each other but remain separated by a fine gap.

Label the marked parts of a neuron in the given figure.                                 [NCERT Exemplar]

(a) Dendrite                 (b) Cell body

(c) Axon                         (d) Nerve endings

Mention the functions of forebrain.

The forebrain performs the following functions:

(i) It is responsible for intelligence, memory, consciousness, will power and voluntary actions.

(ii) It has the centres for visual reception, hearing reception, touch, smell and temperature reception.

Answer the following:                                                                               [NCERT Exemplar]

2. Which hormone is responsible for the changes noticed in females at puberty?

Oestrogen

Dwarfism results due to deficiency of which hormone?

Growth hormone

Blood sugar level rises due to deficiency of which hormone?

Insulin

Iodine is necessary for the synthesis of which hormone?

Thyroxine

Label the endocrine glands in figure.                                                              [NCERT Exemplar]

The endocrine glands are as follow:

(a) Pineal gland                  (b) Pituitary gland

(c) Thyroid gland                (d) Thymus

3. Name the hormones responsible for regulation of

metabolism of carbohydrates, fats and proteins.

Thyroxine

balance of calcium and phosphate.

Parathormone

blood pressure.

Adrenaline

water and electrolyte balance.

Vasopressin

4. What is a tropic movement? Explain with an example.                                 [NCERT Exemplar]

The directional growth movement of plants due to external stimuli is called a tropic movement. It can be either towards the stimulus, or away from it. For example, in case of phototropic movement, shoots respond by bending towards light while roots respond by bending away from it.

5. Why Mimosa pudica (touch-me-not) leaves droop down when touched?

It is due to turgor pressure difference between the upper and lower halves of the base of petiole (pulvinus). Lower half cells lose water and upper half cells of pulvinus become turgid due to transfer of water from lower cells. Thus, the entire leaf droops down when touched.

6. Why are the electrical–chemical signals not an efficient means of communication in plants?

Unlike animals, where there is a nervous system for conduction of nerve impulses and circulatory system for conduction of hormones, there are no specialised tissues in plants. So, the electrical-chemical signals are not an effective means of communication in plants.

7.If a ripened fruit is kept in a basket of raw fruits, then what will happen? What causes it?

The ripened fruit will release ethylene (hormone) which causes ripening of other raw fruits kept in a basket.

8. What is cerebrospinal fluid? What is its function?

Cerebrospinal fluid is the fluid found in the cavities of brain and central canal of spinal cord and in between arachnoid and pia mater.

Function: It prevents the brain and spinal cord from mechanical shocks.

9. Answer the following:    [NCERT Exemplar]

Name the endocrine gland associated with brain.

Pituitary

Which gland secretes digestive enzymes as well as hormones?

Pancreas

Name the endocrine gland associated with kidneys.

Adrenal

Which endocrine gland is present in males but not in females?

Testes