Wednesday, June 18, 2014

Ch. 7 - Control and Coordination class 10 Trendsetter solved CBSE Test paper-02

Class 10 Trendsetter solved CBSE Test paper-02
1. What is a neuron? (1 mark)
Ans: Neuron is the structural &functional unit of nervous system.
2. Give an example of plant hormone that promotes growth. (1 mark)
Ans: auxins, gibberellins and cytokinins
3. What part of the brain maintains posture and equilibrium of the body? (1 mark)
Ans: Cerebellum controls coordination and adjustment of movements (equilibrium) and posture
4. Which parts of the body produce growth regulators? (1 mark)
Ans: Pituitary Gland
5.What is synapse ?
Ans: The junction between neurons is called synapse.
5. List two functions performed by ovaries in a human female. (1 mark)
Ans: (a) Produces ova or egg. (b) Hormones Oestrogen and Progesterone.
6. What does a stem (or shoot) do in a response to light? (1 mark)
Ans: The stem is positively phototropic (grown towards light)
7. Name the 2 hormones secreted by pancreas. Write one function of each hormone. (2 marks)
Ans: (i) Insulin is secreted by the beta cells and like other hormones, passes directly into the blood. Insulin is required to convert glucose into glycogen (glycogensesis) and store it in liver.
(ii) The alpha cells of pancreas secrete glucagon, the metabolic effects of which are opposite to those of insulin. It causes the breakdown of liver glycogen, thereby releasing glucose into the blood stream.
8. How are involuntary actions and reflex actions different from each other? (2 marks)
Ans: Reflex actions are rapid automatic response to a stimulus without the conscious involvement of the brain. E.g.: Withdrawing the hand from a hot object.
Involuntary actions are controlled by the brain but not by our conscious thinking. E.g.: Beating of the heart, peristaltic movement of the intestines
9. What is the difference between a reflex action and walking? (2 marks)
Ans: Reflex action is an involuntary action and mostly controlled my spinal cord whereas walking is a voluntary action and it is controlled by brain.
10. What is the need for a system of control and coordination in an organism? (2 marks)
Ans:  (a). Maintain a steady state of stability in constantly changing environment
 (b) For adjustment of the vital activities of life
(c) To maintain homeostasis.
11. Distinguish between cerebrum and spinal cord. (2 marks)
Ans:
Cerebrum
Spinal cord
It is the largest portion of the brain consisting of two hemispheres
Portion of Central nervous system that conducts impulse to and from the brain
In cerebrum grey matter covers the white matter.
In spinal cord white matter covers the grey matter.
Controls different thought and action such as orientation, recognition, emotions,  memory and speech.
The spinal cord carries out sensory, integrative, and motor functions in order to transmit impulses to the brain.

12. Define the following terms:  (i) nerve impulses (ii) axon (iii) olfactory receptors. (3 marks)
Ans: (i) Nerve impulse : A nerve impulse is a way of two nerve cells to communicate with one another. Nerve impulses are mostly electrical signals along the dendrites. Neurons, also known as brain cells, produce nerve impulses. A nerve impulse is also called an action potential.
(ii) axon : An axon  also known as a nerve fibre is a long, slender projection of a nerve cell or neuron  that conducts electrical impulses away from the neuron's cell body. The function of the axon is to transmit information to different neurons, muscles and glands.
(iii) Olfactory receptors: These are a pair of small, solid, cube shaped bodies. They are fully covered by cerebrum. They receive impulse for smell
13. What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise? (3 marks)
Ans: Receptors are sensory structures (organs/tissues or cells) present all over the body. The receptors are
either grouped in case of eye or ear, or scattered in case of skin.

Functions of receptors:
(i) They sense the external stimuli such as heat or pain.
(ii) They also trigger an impulse in the sensory neuron which sends message to the spinal cord.

When the receptors are damaged, the external stimuli transferring signals to the brain are not felt. For example, in the case of damaged receptors, if we accidentally touch any hot object, then our hands might get burnt as damaged receptors cannot perceive the external stimuli of heat and pain.

14. (a) What are ‘hormones’?
(b) List four characteristics of hormones.
(c) Name the hormones required for the following:
(i) Functioning of memory glands.         (ii) Regulation of calcium and phosphate in blood.
(iii) Lowering of blood glucose.            (iv) Development of moustache and beard in human male
Ans:(a) Hormones are chemical substances which are directly poured into the blood stream by the endocrine glands and have effects on special target organs.
(b) General characteristics of hormones are as follows:
a)    Hormones are secreted by endocrine cells.
b)    Hormones are chemical messengers.
c)    The are chemical signals that circulate in the body fluids.
d)    The hormones regulate the behavior of the target cells.
e)    Hormones, unlike enzymes do not catalyze any reaction.
(c) The hormones required for the following:
(i) Functioning of memory glands. Follicle stimulating Hormone      
(ii) Regulation of calcium and phosphate in blood.:- parathyroid hormone
(iii) Lowering of blood glucose.-  insulin 
(iv) Development of moustache and beard in human male : Testosterone

15. (a) What is autonomic nervous system? Name the subsystem in which it is subdivided? [2]
(b) How do auxins help in bending of stem towards light ? Explain.[3]
Ans:
(a) The autonomic nervous system (ANS) is that part of the peripheral nervous system that largely acts independent of conscious control (involuntarily) and consists of nerves in cardiac muscle, smooth muscle, and exocrine and endocrine glands. It is responsible for maintenance functions (metabolism, cardiovascular activity, temperature regulation, digestion) that have a reputation for being outside of conscious control .
                                     The autonomic nervous system is typically divided into two main subsystems, the sympathetic nervous system and the parasympathetic nervous system.

(b) When growing plants detect light a hormone called Auxin, synthesized at the shoot tip helps the cells to grow longer. When light is coming from one side of the plant, Auxin diffuses towards the shady side of the shoot. This concentration of Auxin stimulates the cells to grow longer on the side of the shoot which is away from light. Thus plant appears to bend towards light.


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