CBSE Class 10 Science Control and Coordination Assignment Set A

Question. Which of the following is not a plant hormone ?
(a) auxin
(b) ascorbic acid
(c) cytokinin
(d) abscisic acid

Answer : B

Question. One of the following plant hormones is responsible for the phenomenon of phototropism in plants. This is :
(a) gibberellin
(b) eltroxin
(c) cytokinin
(d) auxin

Answer : D

Question. The movement of a plant part in response to the force of attraction exerted by the earth is called :
(a) hydrotropism
(b) geotropism
(c) chemotropism
(d) phototropism

Answer : B

Question. The movement of sunflower in accordance with the path of the sun is due to :
(a) photonasty
(b) phototropism
(c) hydrotropism
(d) chemotropism

Answer : B

Question. The plant part which exhibits negative geotropism is :
(a) root
(b) stem
(c) branch
(d) leaves

Answer : B

Question. A big tree falls in a forest but its roots are still in contact with the soil.
The branches of this fallen tree grow straight up (vertically). This happens in response to 
(a) water and light
(b) water and minerals
(c) gravity and water
(d) light and gravity

Answer : D

Question. Which of the following is not caused by a growth movement ?
(a) bending of the shoot of a plant in response to light
(b) closing up of leaves of a sensitive plant on touching with an object
(c) climbing up of a plant on an object by using tendrils
(d) movement of the root of a plant towards a source of water

Answer : B

Question. The root of a plant is :
(i) positively phototropic but negatively geotropic
(ii) positively geotropic but negatively phototropic
(iii) negatively phototropic but positively hydrotropic
(iv) negatively hydrotropic but positively phototropic
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)

Answer : B

Question. The main function of the plant hormone called abscisic acid is to :
(a) increase the length of cells
(b) promote cell division
(c) inhibit growth
(d) promote growth of stem and roots

Answer : C

Question. The growth of tendrils in pea plants is due to the :
(a) effect of sunlight on the tendril cells facing the sun
(b) effect of gravity on the part of tendril hanging down towards the earth
(c) rapid cell division and elongation in tendril cells that are away from the support
(d) rapid cell division and elongation in tendril cells in contact with the support

Answer : C

Question. Which of the following phytohormone is not associated with the promotion of growth in plants ?
(a) auxin
(b) abscisic acid
(c) gibberellin
(d) cytokinin

Answer : B

Question. The plant hormone which triggers the fall of mature leaves and fruits from the plant body is :
(a) auxin
(b) gibberellin
(c) abscisic acid
(d) cytokinin

Answer : C

Question. Which of the following terms denotes the movement of the root of a plant towards moisture in the soil ?
(a) thigmotropism
(b) chemotropism
(c) hydrotropism
(d) geotropism

Answer : C

Question. The growth of a pollen tube towards the ovule caused by a sugary substance as stimulus is an example of :
(a) phototropism
(b) chlorotropism
(c) gravitropism
(d) chemotropism

Answer : D

Question. The bending of the shoot of a plant in response to light is called :
(a) geotropism
(b) phototropism
(c) thigmotropism
(d) photonasty

Answer : B

Question. The stimulus in the process of thigmotropism is :
(a) touch
(b) gravity
(c) light
(d) chemical

Answer : A

Question. A growing seedling is kept in a dark room. A burning candle is placed near it for a few days. The top part of seedling bends towards the burning candle. This is an example of :
(a) chemotropism
(b) hydrotropism
(c) phototropism
(d) geotropism

Answer : C

Question. Which of the following acts as a stimulus in the process of hydrotropism ?
(a) hydrocarbon
(b) hydrogen oxide
(c) hydrogen chloride
(d) hydrogen peroxide

Answer : B

Question. The growth movement of a plant part in response to the touch of an object is called :
(a) thigmonasty
(b) hydrotropism
(c) thigmotropism
(d) geotropism

Answer : C

Question. The climbing organs of plants like tendrils grow towards any support which they happen to touch and wind around the support. This is an example of :
(a) chemotropism
(b) nastic movement
(c) thigmotropism
(d) geotropism

Answer : C

Question. The rate of growth in roots is decreased by one of the following plant hormones. This plant hormone is :
(a) gibberellin
(b) auxin
(c) cytokinin
(d) ethene

Answer : B

Question. When the leaves of a Mimosa pudica plant are touched with a finger, they fold up quickly. This is an example of :
(a) chemotropism
(b) thigmonasty
(c) photonasty
(d) thigmotropism

Answer : B

Question. Dandelion flowers open the petals in bright light during the daytime but close the petals in dark at night.
This response of dandelion flowers to light is called :
(a) phototropism
(b) thigmonasty
(c) chemotropism
(d) photonasty

Answer : D

Question. To which of the following directional stimulus roots of a plant do not respond ?
(a) moisture
(b) candle light
(c) touch
(d) gravity

Answer : C

Question. One of the following is not caused by the growth related movement of the concerned plant part. This is :
(a) phototropism
(b) photonasty
(c) thigmonasty
(d) thigmotropism

Answer : C

Question. The bending of the root of a plant away from a source of light is caused by a plant hormone called :
(a) cytokinin
(b) gibberellin
(c) abscisic acid
(d) auxin

Answer : D

Question. Most of the plant hormones promote plant growth. A plant hormone which inhibits growth is :
(a) abscisic acid
(b) ethene
(c) ascorbic acid
(d) cytokinin

Answer : A

Question. The movement of a shoot towards light is :
(a) geotropism
(b) hydrotropism
(c) chemotropism
(d) phototropism

Answer : D

Question. The bending of the stem of a plant towards a source of light is caused by the action of a phytohormone known as :
(a) abscisic acid
(b) auxin
(c) gibberellins
(d) cytokinin

Answer : B

Question. Which of the following plant part exhibits negative phototropism ?
(a) root
(b) branch
(c) leaves
(d) stem

Answer : A

Question. Which of the following are not tropisms ?
(i) growing of pollen tube in response to a sugary substance
(ii) folding up of leaves of sensitive plant in response to touch
(iii) winding of tendril around a support in response to touch
(iv) opening up of the leaves of a daisy flower in response to light
(a) (i) and (ii) (b) (ii) and (iii) (c) (i) and (iv) (d) (ii) and (iv)

Answer : D

Question : Match the following with correct response. 

a. 1-B, 2-D, 3-A, 4-C

b. 1-A, 2-C, 3-B, 4-D

c. 1-D, 2-A, 3-C, 4-B

d. 1-C, 2-B, 3-D, 4-A

 

Answer : B

Explanation: Phototropism refers to the movement of a plant toward a light source; the growth of the parts of plants in response to the force of gravity; the growth or turning of plant roots towards or away from moisture; Chemotropism may be defined as the movement or the growth of the organism in response to a chemical stimulus.

Question : Differentiate between Spinal reflex and Cranial reflex 

Answer :

 

 

 

HOTS QUESTIONS (SOLVED / UNSOLVED)

Q1. Which hormone:

1. prepares the body for action?

2. controls the amount of sugar (glucose) in blood?

3. brings about changes in boys at puberty?

4. brings about changes in girls at puberty?

Ans. a) Adrenaline b) Insulin

c) Testosterone d) Oestrogen

Question : Phytohormones are

SHORT ANSWER QUESTIONS

Question : Name the hormones secreted by the following endocrine glands and specify one function of each:
(a) Thyroid (b) Pituitary (c) Pancreas
Answer : a. Thyroid: Secretes Thyroxine. It regulates metabolism of carbohydrates, fats and proteins.
b. Pituitary: Secretes growth hormone. Growth hormone regulates growth and development of body.
c. Pancreas: Secretes insulin. Insulin lowers blood sugar level.

Question : How does chemical coordination occur in plants? Explain with the help of three examples.
Answer : In plants, chemical coordination occurs through various Phytohormones.
a. Auxins secreted by growing tissues. They provide growth of plants.
b. Gibberellins cause stem elongation, seed germination and flowering.
c. Cytokinin’s present in areas of actively dividing cells like fruits, seeds. Promote cell division.
d. Abscisic acid inhibits growth and respond to environmental stress.

Question : (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. Mention the hormone due to imbalance of which he is
suffering from this 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 there is: (i) Deficiency of growth hormones
(ii) Excess secretion of growth hormones?
Answer : a. The man is suffering with the disease Diabetes. Insulin is the hormone which is
responsible for this disease. Pancreas secretes this hormone.
b. Pituitary gland.
(i) Deficiency of growth hormone causes dwarfism.
(ii) Excess secretion of growth hormone cause gigantism in a person.

Question : Draw and label a Neuron. Explain how it carries messages.
Answer : Information from the environment is detected by dendritic tip of a neuron located in the sense organ. A chemical reaction sets off here and it creates an electrical impulse which travels from dendrite to cell body and then along the axon to its endings where it sets off the release of some chemicals. The chemicals cross the synapse and set off a similar electrical impulse in dendrites of next neuron.Another synapse at the end of its axon delivers the impulse to the other cells like muscles cells / glands (effector organs) which react to perform the action.

Question :(a) Name the part of brain which controls :
(i) voluntary action (ii) involuntary action.
(b) What is the significance of the peripheral nervous system? Name the components of this nervous system and distinguish between the origin of the two.
Answer : .a.(i) Voluntary actions - cerebellum; (ii) Involuntary action — medulla oblongata.
b. The communication between the central nervous system and the other parts of the body is facilitated by the peripheral nervous system. Cranial nerves arise from the brain; spinal nerves arise from the spinal cord.

LONG ANSWER QUESTION

Question : Draw a labelled diagram of human brain. Discuss functions of cerebrum, cerebellum and medulla.
OR
Draw and describe the role of various parts of human brain.
Answer : Human brain has three major parts:
a. Fore-Brain contains mainly cerebrum b. Mid-brain c. Hind-brain

Functions: a. Cerebellum which controls posture, balance of body and accurate voluntary movements.
b. Pons regulates respiration
c. Medulla oblongata which controls involuntary actions like blood pressure, salivation, vomiting etc.

Question : Give the function(s) of the following plant hormones:
a. Auxins b. Gibberellins c. Cytokinins d. Abscisic acid e. Ethylene
Answer : .a. Auxins promote cell elongation, root formation, cell division, etc. It also promotes fruit growth.
b. Gibberellins stimulate stem elongation, seed germination and flowering.
c. Cytokinins help in breaking the dormancy of seeds and buds. They delay ageing in leaves.
They also promote the opening of stomata.
d. Abscisic acid promotes falling of leaves and fruits.
e. Ethylene promotes ripening of fruits

Question : (a) Draw the structure of a neuron and label the following on it:
Nucleus, Dendrite, Cell body and Axon.
(b) Name the part of neuron :
(i) Where information is acquired.
(ii) Through which information travels as an electrical impulse.
Answer : (a) 

b. (i) Dendrite (ii) Axon

Question : Describe an activity to illustrate the phenomenon of phototropism and explain why does this occur.
Answer : 

a. Take a plant and make such an arrangement that it receives the light coming from a window as shown in the figure and observe it for few days.
b. Now,turn the flask so that the shoots are away from light and the roots towards light.
Leave it undisturbed in this condition for a few days.
c. Again, observe carefully to find the difference in the movement.
d. When growing plants detect light, auxin, synthesized at the shoot tip, helps the cells to grow longer. Auxin always 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, the plant appears to bend towards light.

Question :  (a) What is Phototropism and Geotropism? With labelled diagrams describe an activity to show that light and gravity change the direction that plant part grows in.
(b) Mention the role of each of the following plant hormones:
(i) Auxin (ii) Abscisic acid.
Answer : a. Phototropism It is tropic movements in the direction of light or away from it e.g. shoots bend towards light while roots grow away from it. Hence shoot is positively phototropic and root is negatively phototropic.

Geotropism: Growth of roots downward towards the earth hence positively geotropic whereas stem grows upward, away from earth, hence it is negatively geographic.
b. Auxins: Synthesized at the shoot tip, helps the cells to grow longer.
Abscisic acid: Inhibits growth, causes wilting and falling of leaves.