Friday, 22 January 2016


1) Which of the following is a plant hormone?

(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin

ANSWER: - Cytokinin

2) The gap between two neurons is called a
(a) dendrite.
(b) synapse.
(c) axon.
(d) impulse.


3) The brain is responsible for
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.

ANSWER:- all of the above.

4) What is the function of receptors in our body?
Think of situations where receptors do not work properly. What problems are likely to arise?

ANSWER:- Receptors are sensory structures (organs/tissues or cells) present all over the body.
When the receptors are damaged, the external stimuli transferring signals to the brain cannot be felt.

5) Draw the structure of a neuron and explain its function.


Functions of the three parts of a neuron:
Axon: It conducts messages away from the cell body.
Dendrite: It receives information from axon of another cell and conducts the messages towards the cell body.
Cell body: It contains nucleus, mitochondria, and other organelles. It is mainly concerned with the maintenance and growth.

6) How does phototropism occur in plants?

ANSWER:-Environmental triggers such as light will change the directions that plant parts grow in. These directional, or tropic, movements can be either towards the stimulus, or away from it. So, in two different kinds of phototropic movement, shoots respond by bending towards light while roots respond by bending away from it.

7) Which signals will get disrupted in case of a spinal cord injury?

ANSWER:-In case of the spinal cord injury, the signals coming from the nerves as well as the signals coming to the receptors will be disrupted.

8) How does chemical coordination occur in plants?

ANSWER:- Plants respond to stimuli by showing movements. The growth, development, and responses to the environment in plants is controlled and coordinated by a special class of chemical substances known as hormones. These hormones are produced in one part of the plant body and are translocated to other needy parts.

9) What is the need for a system of control and coordination in an organism?

ANSWER:-All the movements that occur in response to stimuli are carefully coordinated and controlled. In animals, the control and coordination movements are provided by nervous and muscular systems. The nervous system sends messages to and away from the brain. The spinal cord plays an important role in the relay of messages. In the absence of this system of control and coordination, our body will not be able to function properly.

10) How are involuntary actions and reflex actions different from each other?

ANSWER:-Involuntary actions cannot be consciously controlled. On the other hand, the reflex actions such as closing of eyes immediately when bright light is focused show sudden response and do not involve any thinking. This means that unlike involuntary actions, the reflex actions are not under the control of brain.

11) Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.


Nervous control
Hormonal Control
It is consist of nerve impulses between PNS, CNS and Brain.
It consists of endocrine system which secretes hormones directly into blood.
Here response time is very short.
Here response time is very long.
Nerve impulses are not specific in their action.
Each hormone has specific actions.
The flow of information is rapid.
The flow of information is very slow.

12) What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?


Movement in sensitive plants
Movement in our legs
The movement in a sensitive plant is a response to stimulus(touch) which is a involuntary action.
Movement in our legs is a voluntary action.

No special tissue is there for the transfer of information

A complete system CNS and PNS is there for the information exchange.
Plant cells do not have specialised protein for movements.
Animal cells have specialised protein which help muscles to contract.