MG SCHOOL EDUCATION: 10th Chp 7 Prvs yrs aprd qusns

Class 10 Science

Chapter 7 Control AndCoordination

Previous Years Appeared Questions

MULTIPLE CHOICE QUESTIONS

1.The correct path of the movement of nerve impulses in the following diagram is (April 2019)

A) Q → S → R → P

(B) S → R → Q → P

(D) P → R → S → Q

Ans: (D) P → R → S → Q

2. The incorrect statement related to thyroxine hormone among the following is (April 2020)

(A) it regulates fat metabolism

(B) its deficiency leads to goitre

(D) iodine in the food is essential for its production.

Ans: (C) it is secreted by parathyroid gland

3. The hormone that regulates carbohydrate, protein and fat metabolism in the human body is (July 2021)

(A) Testosterone (B) Adrenaline

Ans: (D) Thyroxin

4. A pot that has growing seedling is kept in a dark room. A burning candle is placed near it for a few days. The top part of the seedling bends towards the light of burning candle. This is (July 2021)

(A) Chemotropism (B) Phototropism (C) Geotropism (D) Hydrotropism

Ans: (B) Phototropism

5. The gap between two neurons is (July 2021)

(A) dendrite (B) axon

Ans: (C) synapse

6. A plant hormone that inhibits the growth of plants is (Sep 2021)

(A) Auxin (B) Gibberellin

Ans: (D) Abscisic acid

7. The centre of reflex action is (Sep 2021)

(A) Cerebrum (B) Spinal cord

Ans: (B) Spinal cord

8. The correct path of movement of electrical impulse in a neuron is (Sep 2021)

(A) Dendrite →Cell body →Axon →Axon end

(B) Axon → Axon end → Dendrite → Cell body

(D) Cell body → Dendrite → Axon end → Axon

Ans: (A) Dendrite →Cell body →Axon →Axon end

9. An example for positive geotropism in plants is (June 2022)

(A) growth of shoot

(B) growth of tendrils of creepers

(D) upward growth of roots.

Ans: (C) growth of roots into deep soil

10. “A person immediately starts running soon after observing a snake.” The correct transmission path of reflex impulse in this situation is (April 2023)

(A) Receptor → Sensory neuron → Brain → Relay neuron → Motor neuron → Effector

(B) Receptor → Sensory neuron → Spinal cord → Relay neuron → Motor neuron → Effector

(D) Effector → Motor neuron → Relay neuron → Brain → Sensory neuron → Receptor

Ans. : (B) Receptor → Sensory neuron → Spinal cord → Relay neuron → Motor neuron → Effector

11. “A person immediately starts running soon after observing a snake.” The correct transmission path of reflex impulse in this situation is (April 2023)

(A) Receptor → Sensory neuron → Brain → Relay neuron → Motor neuron → Effector

(B) Receptor → Sensory neuron → Spinal cord → Relay neuron → Motor neuron → Effector

(D) Effector → Motor neuron → Relay neuron → Brain → Sensory neuron → Receptor

Ans. : (B) Receptor → Sensory neuron → Spinal cord → Relay neuron → Motor neuron → Effector

ONE MARKS QUESTIONS

1. Which hormone inhibits the growth of plants? (June 2022)

Ans. : Abscisic acid

2. What is the role of abscisic acid in plants ? (April 2023)

Ans. : Abscisic acid inhibits growth in plants.

TWO MARKS QUESTIONS

1. Draw the diagram showing the structure of neuron. Label the following parts : (June 2019)

(i) The part which has prominent nucleus (ii) Dendrite.

Ans:

2. A person‘s face has become pale and his breathing rate has increased due to fear. Analyse the process which enables the person to deal with this situation. (Sep 2020)

Ans. :

★ Adrenaline is directly secreted into the blood. The blood to the skin is reduced due to contraction of muscles around small arteries.

★The breathing rate increases because of the contractions of the diaphragm and the rib muscles. The heart beats faster, resulting in supply of more oxygen to the muscles.

3. Mention the function of the following plant hormones : i) Auxin ii) Cytokinin. (April 2022)

Ans: i) Auxin :

Helps the cells in the stems and the cells in the many parts of the plant body to grow longer.

ii) Cytokinin :

★ Promotes cell division in fruits and seeds

★Helps in promoting overall growth of plants.

THREE MARKS QUESTIONS

1. Imagine the following situations :

(i) Clapping at the end of a programme (ii) Fluctuating blood pressure in the body. How these situations are functionally different ? Give reason. (June 2019)

Ans. :

(i) Voluntary action :  Action performed based on thinking  Controlled by forebrain.

(ii) Involuntary action :  Action without thinking control  Controlled by hind brain.

2. We withdraw our leg when stepped on thorn unknowingly.

(a) Trace the sequences of events which occur in this action.

(b) Which part of human nervous system controls this action ? (June 2019)

Ans. : (a)

(i) Receptors receive the stimulus of pain

(ii) Messages reach spinal cord through sensory neuron.

(iii) Responses reach motor neuron through association neuron.

(iv) Responses reach effectors through motor neuron.

(v) Muscles withdraw the leg.

(b) Spinal cord controls this action

FOUR MARKS QUESTIONS

1. Name the given structure. What is its general function ? Mention the function of the parts labelled as A and B. These structures in animals are said to be efficient ways to give quick responses. Why ? (April 2020)

Ans:

★ Reflex arc

★ It gives sudden action in response to the event happening in the environment.

A) Sensory neuron : It conducts the impulse of stimulus from receptor to the spinal cord.

B) Effectors : Which shows the sudden visible response. Reflex arcs have evolved in animals because the thinking process of brain is not fast enough in many animals. Mean while many animals have very little of the complex neuron network needed for thinking.

So it can function in the absence of true thought process and increase the chance of survival.

2. Draw the diagram showing longitudinal section of human brain. Label the following parts :

a) Mid brain b) Gland which stimulates growth in all organs. (Sep 2020)

Ans:

3. a) As the growth advances in a climbing plant ( creeper ) that appears as the plant is moving towards a particular direction. How ?

b) Explain the necessity of chemical communication in animals. (June 2023)

Ans. :

★ For a touch / thigmotropism, when the tendrils of creeper plants come in contact with a support, the plant circles around it and grows faster.

★ When tendrils gets attached to a support then, tips of the plant synthesise auxin hormone at higher concentration and stimulates the elongation of cells, then the plant shows directional movement / growth towards light.

★ In animals chemical communication is necessary. In animals electrical impulses will reach only the cells that are connected by nervous tissue but not each and every cell.

★ Nerve cells cannot create and transmit electrical impulses continuously therefore, chemical communication is necessary in transmitting stimulus continuously to each and every cell.

IMPORTANT QUESTIONS

1. What is the need for a system of control and coordination in an organism?

Ans : An organism needs control and coordination system for the following functions :

(i) To save the body of the organisms from the harmful changes in the environment.

(ii) To control the speed of voluntary and involuntary actions.

(iii) To have the capability to think and learn for responding to any stimuli.

2. What happens at the synapse between two neurons?

Ans : The small empty space between two nerve cells is called synapse. At synapse, a chemical substance is produced at the end of axon of one nerve cell that reaches to the other nerve cell through the dendrite.

3. Which part of the brain maintains posture and equilibrium of the body?

Ans : Posture and equilibrium of the body are controlled by cerebellum.

4. How do we detect the smell of an agarbatti (incense stick)?

Ans : ★ The smell of agarbatti (incense stick) diffuses in the air.

★ It is detected by olfactory receptors present in the nose.

★ This information is sent to olfactory lobe by sensory nerves located in the forebrain.

★ It responds to the information.

5. What are plant hormones? Give an example of a plant hormone that promotes growth.

Ans :

★ Plant hormones are also called phytohormones. Plant hormones are the chemical substances which help in controlling growth, flowering, height, development of plants and their response to the environment. Hormone that promotes growth in plants is

★ Auxin.

6. How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?

Ans :

7. How do auxins promote the growth of a tendril around a support?

Ans : When the tip of a tendril touches a support, then the auxins present in its tip move to that side of tip which is away from the support.

Auxins promote growth. So, due to more auxins in it, the side of tendril away from the support grows faster (and becomes longer) than the side which is in contact with the support and makes the tendril twirl (or bend) around the support.

8. Which signals will get disrupted in case of a spinal cord injury?

Ans : (i) All the involuntary actions will get disturbed.

(ii) Reflex actions will be disturbed because reflexes are located in the spinal cord. Therefore, the quick responses required to safe guard the body will not take place.

9. Design an experiment to demonstrate hydrotropism.

Ans : Equipments requires : Glass through , water container , soil and a plant

Procedure : As shown in figure , in glass through take a soil , plant and keep the water containing cup just away from the plant. Keep this set up for few days.

Observation : Roots grow towards wet area

Decision : Roots show hydrotropism

10. How does phototropism occur in plants?

Ans : The movement in any part of a plant due to light is called phototropism.

The shoot of plant shows positive phototropism and roots show negative phototropism.

Phototropism in plants occurs due to the hormone auxin. When light falls on one side of a plant, the secretion of auxin hormone is more in the part away from the light.

Hence, auxin causes growth in length of the cells in shady part. So, the plant appears to bend towards light.

11. How are involuntary actions and reflex actions different from each other?

Ans:

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

Ans:

13. What are the parts of hind brain ? Mention their functions.

Ans :

(i) Cerebellum : it controls posture and equilibrium of the body

(ii) Medulla : Involuntary actions including blood pressure, salivation and vomiting are controlled by the medulla

14. Name the endocrine glands found attached with following organs and mention the hormones secreted by these glands. (i) Brain (ii) Kidney

Ans :

(i) Brain : Pituitary gland , secretes growth hormones

(ii) Kidney : Adrenal gland , helps in metabolism, regulates blood pressure, and is responsible for the fight or flight response.

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

Ans :

★ Insulin hormone regulates blood sugar levels.

★ To treat increased level of blood sugar, the diabetic patients are treated by giving injections of insulin.

16. What is the significance of tropic movements in plants ? Explain any two types of tropic movements.

Ans :

★ Tropic movement help in the protection of plants.

★ It helps to develop a sudden response during any charge.

★ This movement also helps in the growth and development of plants by facilitating the movement of root, stem, and leaves towards the stimuli like sunlight, nutrients, water, etc.

Phototropism : Movement of shoot towards light.

Geotropism : Movement roots towards gravity / shoots away from gravity.

17. Where are different receptors present in our body ? What are their functions ?

Ans :

(i) Phonoreceptors are found in Ear. Their function is to hear and balance of the body.

(ii) Photoreceptors are found in Eyes. Their function is to see.

(iii) Olfactory receptors are found in Nose. Their function is smell detection.

(iv) Thermoreceptors found in Skin.- Its function is to feel the heat, cold or touch.

(v) Gustatory receptors found in Tongue - Its function is to detect Taste.

18. Which hormone is known as emergency hormone in our body ? How it helps in coping during emergency ?

Ans : Adrenaline hormone is known as the Emergency Hormone

★ Adrenaline increases the heart beat and breathing rate which results in the supply of more oxygen to muscles. Hence the rate of metabolism increases.

★ This helps the person think rapidly and respond to situation. 19. How does our body respond when adrenaline is secreted into the blood? Ans. When adrenaline is secreted into the blood, it prepares our body for action.

★ It speeds up heart beat and breathing, raises blood pressure and allows more glucose to go into the blood to give us a lot of energy quickly to fight or urn away from frightening situation.

★ The blood supply decreases form the skin and digestive system and increase to skeletal muscles.

★ All these conditions help the individual to respond the emergency situation.

20 How endocrine glands do helps in maintaining feedback control?

Ans. The timing and amount of hormones released are regulated by feedback mechanism. For example, glucose level in the blood is maintained constant by feedback mechanism.

a) High glucose level in the blood induces the pancreatic cells to produce insulin which converts glucose to glycogen.

b) Less glucose level in the blood do not induce the pancreatic cells to produce insulin so that less conversion of glucose to glycogen may occur.