class 10 science ch 7 important question


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Chapter 7 Summary for revision

  • Any change in environment to which an organism responds and reacts is called stimulus. Plants not only respond to light but show tropisms in response to other stimuli as well.
  • Plants not only respond to light but show tropisms in response to other stimuli as well.
  • Phytohormones are of different types e.g. Auxins, gibberellins, adscisic acid and ethylene.
  • flowering and seed germination in plants are regulated by the duration of light. This is known as photoperiodism.
  • Body functions of animals are controlled and coordinated by two systems : nervous and endocrine system.Structural and functional units of nervous system are neurons. Each neuron is formed of three parts : nucleated cyton and cell body. small sized branched dendrons and a long axon.
  • Nervous control and coordination of body functions involves three systems : Receptors organs, Nervous system and effectors (e.g. muscles and glands).
  • Nervous system is differentiated into three systems : CNS, PNS and ANS.
  • Central nervous system is formed of brain and spinal cord.
  • Human brain lies in the cavity of cranium of skull and is formed of three parts: Fore brain , mid brain and hind brain.
  • Fore brain is composed of olfactory lobes (for smell). cerebrum (controls voluntary movements and locomotion) and diencephalamus (formed of thalami and hypothalamus).
  • Each cerebral hemisphere is divided into four lobes: Frontal, parietal, temporal and occipital lobe, each of which is concerned with specific function.
  • Hind brain is formed of three lobes : Cerebellum (control posture and equilibrium of body); Pons (coordinated the muscles of two sides) and medulla oblongata (controls involuntary functions of body).
  • Spinal cord lies in the neural canal of vertebral column and controls reflex actions.
  • Peripheral nervous system is formed of two types of nerves: 12 pairs of cranial nerves and 31 pairs of spinal nerves.
  • Autonomic nervous system controls the involuntary actions of visceral organs.
  • Reflex actions are spontaneous, automatic, and involuntary mechanical responses. These are controlled by spinal cord, while path followed in reflex action is called reflex arc.
  •   Plants are generally rooted in the soil so are mostly non-motile.
  • Geotropism involves the orientation of body parts of plants in relation to gravitational pull of earth.
  • Phototropism is the movement of body parts of plants in relation to direction of light stimuli.
  • In seismonastic movements, mechanical stimuli like touch, etc., lead to folding of leaflets in plants like touch-me-not and they are sensitive plant
  • In hydrotropism, movements of root occurs in the direction of (towards) water.
  • Endocrine system is formed of endocrine and ductless glands whose secretions are called hormones and are generally released in the blood.
  • Hormones and secretions of endocrine glands. They are produced in small amounts and have specific function on the specific target organs.
  • Thyroid gland secretes thyroxine hormone which controls BMR. Its deficiency causes cretinism.
  • Hypothalamus secretes releasing hormones which regulate hormonal secretions from anterior lobe of pituitary.
  • Pituitary is commonly called Master gland of the body as its tropic hormones control the hormonal secretions from a number of other endocrine glands.
  • Pancreas secretes two hormones: Insulin and glucagon which collectively regulate glucose level in the blood.
  • Endocrine part of testes secretes testosterone which regulates growth and functioning of secondary sexual characters related to male.
  • Ovaries secrete estrogens and progesterone. Estrogens regulate growth and functioning of secondary sexual characters of female type, while progesterone maintains pregnancy.
  • Endocrine glands and nervous system together form the integrating system.
  • class 10 science ch 7 important question
class 10 science ch 7 important question
class 10 science ch 7 important question

Important Questions chosen from Previous Years Board Exam Papers

Very Short Answer Questions:

1. What will happen to a plant shoot if sunlight falls on it from one direction only? What do you call this movement? (2012-13)Solution:Stem shoot will move towards light direction side. This type of movement is called Phototropism.


2. Name two tissues which provide control and coordination in animals. (2012-13)Solution:Nervous tissue and muscular tissue provide control and coordination in animals.

3. Why is it advised to use iodised salt in our diet. (2014-15)Solution:Because iodine is an essential component of thyroxine hormone which control basal metabolic rate (BMR) of body.

4. State one example of chemotropism. (2014-15Solution:Pollen tube passes thorough style, ovary and reaches ovule due to chemotropism.


5. Name one plant growth hormone which retards growth during extreme dry season. (2015-16)Solution:Abscisic acid

Short Answer

Questions:1. (a) Which organ secretes a hormone when blood sugar rises? Name a digestive enzyme released by this organ.(b) Why pancreas helps in digestion and regulation of blood sugar? (2012-13)Solution:(a) Pancreas secretes insulin hormone when blood sugar rises. It secretes trypsin enzyme to digest proteins.(b) Pancreas secretes pancreatic juice to digest proteins, carbohydrates and fat of food.


2. Name the hormone which are responsible for the following functions:(i) Regulating the blood sugar levels.(ii) Regulating the carbohydrates, protein and fat metabolism in the blody.(iii) Changes at puberty in human female.(iv) Regulating the growth and development of the body.

Solution:(i) Insulin of pancreas(ii) Thyroxine of thyroid.(iii) Estrogens of ovaries(iv) Growth hormone of anterior pituitary.4.

 (a) An old man is advised by his doctor to take less sugar in his diet. Name the disease from which the man is suffering from. Mention the hormone due to imbalance of which he is suffering from the disease. Which endocrine gland secretes this hormone?

(b) Name the endocrine gland which secretes growth hormone. What will be its effect on a person if:(i) Deficiency of growth hormone.(ii) Excess secretion of growth hormone (2013-14)

Solution:(a) Old person is suffering from diabetes mellitus caused due to deficiency of insulin hormone. Insulin is secreted by cells of Islets of largerhans of pancreas.(b) Growth hormone is secreted by anterior pituitary. Its deficiency causes dwarfism while its excess secretion causes gigantism.

5.  Name the plant hormone responsible for the following functions (2014-15)(i) Growth of the stem(ii) Promotes cell division(iii) Wilting of leaves(iv) Inhibits growthSolution:(i) Gibberellin(ii) Cytokinins(iii) Ethylene(iv) Abscisic acid

6. How do auxins promote growth of a tendril around a support? (2015-16)Solution:Tendrils are sensitive to touch. Due to effect of auxins when tendrils come in contact with support, the part of tendril in contact with subject does note grow so rapidly as part of tendril not in contact with object.


7. Mention three major regions of brain. Write one function of each. (2015-16)Solution:(a) Fore brain- controls voluntary functions, will power, memory, reasoning, speech, etc.(b) Mid brain – controls visual and auditory sensations.(c) Hind brain – controls involuntary functions, equilibrium and posture of body.

8. A doctor advised a patient to go on a diet without sugar and take insulin injections also. Name the disease he is suffering from. Why has he been given the two advice? (2016-17)Solution:Patient is suffering from diabetes mellitus disease characterized by deficiency of insulin level so is not able to store excess of sugar as glycogen. So the doctor gave him these two advices.

9. A motorcycle rider without helmet met an accident and suffered a spinal cord injury. In this case which signals will get disturbed and why? (2016-17)Solution:As spinal cord is the center of reflex actions and movements of lower parts of body so main side effects of spinal injury are: Paralysis of any part of body; tingling or loss sensation in hands, fingers, feet or toes; extreme back pain; etc. Severity of symptoms depends upon place in injury and its severity.

10 What are plant hormone ? Name the plant hormones responsible for: (outside Delhi 2019)(i) Growth of stem(ii) Promotion of cell division(iii) Inhibition growth(iv) Cell elongation.Solution:Plant hormones, also called phytohormones, are plant growth regulator chemicals which wither promote or inhibit the growth of the plants.(i) Gibberellins(ii) Cytokinin(iii) Abscisic acid(iv) Auxinsclass 10 science ch 7 important question


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