Control and Coordination


What is 'hydrotropism'? Describe an experiment to demonstrate 'hydrotropism'.


'Hydrotropism' is the directional growth of a plant part in response to water. For example, roots show hydrotropism as they grow towards water in the soil and are positively hydrotropic.
An experiment to demonstrate hydrotropism is as follows:

  1.  A porous pot filled with water is taken and inserted in a tub filled with dry sand.
  2. A freshly germinated pea seedling is sowed in the sand.
  3. As water is not available in sand, the root growing will bend towards the porous pot filled with water.
  4. A hydrotropic curvature of the root is observed as it grows towards water.
  5. This bending of root shows the movement in response towards water.

Control and Coordination

Q 1.

What is the scientific name of sensitive plant ?

Q 2.

Name one plant hormone that promotes growth and another plant hormone which inhibits growth.

Q 3.

(a) What does a plant root do in response to water ? What is this phenomenon known as ?
(b) What happens to the moonflower (i) during daytime, and (ii) at night ? What is this phenomenon known as ?

Q 4.

What are the scientific names for the following receptors in animals ?
(a) receptors for light
(b) receptors for heat
(c) receptors for sound
(d) receptors for smell
(e) receptors for taste

Q 5.

In what ways are puberty and adolescence result of the activity of some glands in the human body ?

Q 6.

(a) Write the names of five endocrine glands found in the human body. Name the hormones secreted by each gland.
(b) How do hormones reach the organs they control ?
(c) Name the gland which controls the secretion of hormones from the pituitary.
(d) How does our body respond when adrenaline is secreted in large amounts into the blood ?
(e) Name the disease which occurs in adults due to the deficiency of iodine in the diet. What is the main symptom of this disease ?

Q 7.

Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in the given figure.

Q 8.

Mention one function for each of these hormones:
(a) Thyroxin (b) Insulin (c) Adrenaline (d) Growth hormone (e) Testosterone.

Q 9.

Name various plant hormones. Also give their physiological effects on plant  growth and development.  

Q 10.

What is synapse ? In a neuron cell how is an electrical impulse created and what is the role of synapse in this context ?

Q 11.

Name the plant hormones which help/promote (i) cell division (ii) growth of
the stem and roots?

Q 12.

Which one of the following actions on touch is an example of chemical control?
(i) Movement on the touch-sensitive plant.
(ii) Movement in human leg.

Q 13.

What is a plant hormone ? Name four plant hormones. State one function of each.

Q 14.

Name the plant organs which are :
(a) positively phototropic (b) positively geotropic
(c) negatively geotropic (d) positively hydrotropic

Q 15.

Why is the closing of a dandelion flower at dusk (when it gets dark) not a tropism ?

Q 16.

a) What are the short fibres of a neuron known as ?
What is the long fibre of a neuron known as ?

Q 17.

Why are some patients of diabetes treated by giving injections of insulin ?

Q 18.

What part does the diet play in helping us to have a healthy thyroid gland ?

Q 19.

What are the two main communications systems in an animal’s body ?

Q 20.

(a) The human brain can be broadly divided into three regions. Name these three regions.
(b) What is cranium ? What is its function ?

Q 21.

Compare the nervous system and endocrine system (hormonal system) for control and coordination in humans.

Q 22.

State the functions of the following hormones :
(a) Thyroxine (b) Adrenaline (c) Growth hormone

Q 23.

A person walks across a room in barefeet and puts his foot on a drawing pin lying on the floor. He lets out a cry. Explain what happens in his nervous system in bringing about this response.

Q 24.

What does CNS stand for ? Which part of CNS : (a) consists of two cerebral hemispheres, and (b) has spinal nerves attached to it ?

Q 25.

When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what the following are examples of :
(a) the smell of the food
(b) the cells in your nasal passages which perceive the smell
(c) the gland which is stimulated to secrete saliva.

Q 26.

What is a tropic movement? Explain with an example.

Q 27.

What will happen if intake of iodine in our diet is low?

Q 28.

Answer the following:
(a) Which hormone is responsible for the changes noticed in females at puberty?
(b) Dwarfism results due to deficiency of which hormone?
(c) Blood sugar level rises due to deficiency of which hormone?
(d) Iodine is necessary for the synthesis of which hormone?

Q 29.

Mention the receptors for light and sound in animals.

Q 30.

Mention the names of various phytohormones.

Q 31.

Discuss phototropism.

Q 32.

Describe the central nervous system in human beings.

Q 33.

Write the functions of any one part of the hind – brain.

Q 34.

List the functions of testosterone and estrogen.

Q 35.

Write name of three hormones secreted by the pituitary gland.

Q 36.

What is coordination?

Q 37.

What are hormones?

Q 38.

What are phytohormones?

Q 39.

What are meanings? What are their functions? Name the fluid, which is filled in between meanings.

Q 40.

How does control and coordination occur in single-celled animals?

Q 41.

Name any two phytohormones, which are growth promoters.

Q 42.

Name any growth inhibiting phytohormone.

Q 43.

State the structural and the functional unit of the nervous system. Draw its neat labelled diagram and write two functions.

Q 44.

State the function of:
(i) gustatory receptors, and
(ii) olfactory receptors.

Q 45.

Name the part of the brain which controls posture and balance of the body.

Q 46.

Mention the part of the body where gustatory and olfactory receptors are located.

Q 47.

(a) Which plant hormone is present in greater concentration in the areas of rapid cell division?
(b) Give one example of a plant growth promoter and a plant growth inhibitor.

Q 48.

Name any three endocrine glands in human body and briefly write the function of each of them.

Q 49.

Which part of the brain controls involuntary actions? Write the function of  any two regions of it.

Q 50.

What is chemotropism? Give one example. Name any two plant hormones and mention their functions.