Solutions of Control and Coordination Lakhmir Singh Manjit Kaur MCQ and HOTS Pg No. 94 Class 10 Biology
Multiple Choice Questions (MCQs)-Pg-94
38. Which of the following is not a plant hormone?
A. auxin
B. ascorbic acid
C. cytokinin
D. abscisic acid
Answer
→ Ascorbic acid, also known as Vitamin C, is a vitamin found in food particularly in citrus fruits and green vegetables.
39. 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
→ Auxin, which is present at the tip of shoot, is responsible for the phenomenon of phototropism in plants.
40. 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
→ Geotropism is the movement of a plant part in response to a stimulus (gravity).
41. The movement of sunflower in accordance with the path of the sun is due to:
A. photonasty
B. phototropism
C. hydrotropism
D. chemotropism
Answer
→ Phototropism is the movement of a plant part in response to a stimulus (light). Hence, the movement of sunflower in accordance with the path of the sun is due to phototropism.
42. The plant part which exhibits negative geotropism is:
A. root
B. stem
C. branch
D. leaves
Answer
→ Negative geotropism is the movement of a plant part against the direction of gravity. For example, Stem or shoot grow outside the soil.
43. 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
→ The roots show positive geotropism and stem or other aerial parts of plants show negative geotropism. Its reverse, the roots show negative phototropism while other aerial parts show positive geotropism.
44. 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
→ Closing up of leaves of a sensitive plant on touching with an object (also known as Thigmonasty) is not caused by a growth movement.
45. The root of a plant is:
Options -
(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
→ The root of plant grows in response to gravity inside the soil. Hence, it is positively geotropic but negatively phototropic.
46. 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
→ Abscisic acid is the growth inhibitor plant hormone.
47. 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
→ The growth of tendrils in pea plants is due to the rapid cell division and elongation in tendril cells that are away from the support.
48. 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
→ Abscisic acid is the growth inhibitor plant hormone.
49. 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
→ Abscisic acid, the growth inhibitor plant hormone, triggers the fall of mature leaves and fruits from the plant body.
50. 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
→ Hydrotropism is the movement of a plant part in response to water. The water is the stimulus in this process.
51. 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
→ Due to chemical stimulus, the growth of a plant part is known as chemotropism. For example, a sugary substance can induce to the growth of pollen tube towards the ovule. Here, sugary substance works as a stimulus and this process represents the positive chemotropism.
52. The bending of the shoot of a plant in response to light is called:
A. geotropism
B. phototropism
C. thigmotropism
D. photonasty
Answer
→ The process of bending of a shoot towards light is known as phototropism.
53. The stimulus in the process of thigmotropism is:
A. touch
B. gravity
C. light
D. chemical
Answer
→ Thigmotropism is the movement of a plant part in response to touch. Touch is the stimulus in this process.
54. 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
→ The process of bending of a shoot towards light is known as phototropism.
55. 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
→ Hydrogen oxide (OH) acts as a stimulus in the process of hydrotropism.
56. 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
→ Thigmotropism is the movement of a plant part in response to touch of an object. Touch is the stimulus in this process.
57. 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
→ The process of winding of tendril around a support is known as thigmotropism.
58. 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
→ Auxin has adverse effect on growth rate of roots hence, it decrease the growth rate of roots.
59. 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
→ Thigmonasty is the non-directional movement of a plant part in response to the touch. The folding up of Mimosa pudica (touch me not or chui-mui) leaves when touching is an example of this process.
60. 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
→ Photonasty is the non-directional movement of a plant part (e.g. petals of flowers) in response to light. The opening and closing of petals of dandelion flowers in response to light intensity is an example of this process.
61. To which of the following directional stimulus roots of a plant do not respond?
A. moisture
B. candle light
C. touch
D. gravity
Answer
→ Touch is a directional stimulus roots of a plant do not respond.
62. 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
→ Thigmonasty is the non-directional movement of a plant part in response to the touch. The folding up of Mimosa pudica leaves when touching is an example of this process.
63. 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
→ Auxin is the hormone that causes phototropism in plants.
64. 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
→ Abscisic acid is the growth inhibitor plant hormone.
65. The movement of a shoot towards light is:
A. geotropism
B. hydrotropism
C. chemotropism
D. phototropism
Answer
→ The process of bending of a shoot towards light is known as phototropism.
66. 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
→ Auxin is the phytohormone which is responsible for the bending of the stem of a plant towards a source of light. This hormone is present at shoot tip.
67. Which of the following plant part exhibits negative phototropism?
A. root
B. branch
C. leaves
D. stem
Answer
→ Negative phototropism is the process in which roots of plants bend away from light.
68. 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
→ Folding up of leaves of sensitive plant in response to touch is known as photonasty which is not a type of tropism. Opening up of the leaves of a daisy flower in response to light is also not an example of tropism.
Questions Based on High Order Thinking Skills (HOTS)-Pg-96
69. The chemical substance P is made and secreted by the meristematic tissue at the tip of stem (or shoot) of a plant. The chemical substance P is responsible for a phenomenon Q in plants in which the stem bends towards a source of light. The same chemical substance P has an opposite effect on the root of a plant. It causes the root of a plant to bend away from the source of light in a process called R.
(a) What is the chemical substance P?
(b) State whether P prefers to remains in the sunlight side of a stem or in shade.
(c) What is the effect of substance P on the rate of growth of (i) a root, and (ii) a stem?
(d) What is the name of process (i) Q, and (ii) R?
(e) What is the general name of chemical substances like P? Name another substance which belongs to this class of chemical substances.
Answer
→ (a) From the given question, the chemical substance P is Auxin which is produced at the shoot tip and can diffuse to other plant parts.
(b) Auxin moves to the darker side of the plant, causing the cells there to grow large.
(c) Auxin has adverse effect on growth rate of roots hence, it decrease the growth rate of roots. Unlike roots, the auxin has positive effect on growth rate of stem hence, it increases the growth rate of stem.
(d) Process Q is positive phototropism while process E is negative phototropism. Growth towards a light source is called positive phototropism, while growth away from light is called negative phototropism.
(e) Chemical substance like P is Auxin, a Phytohormone or plant hormone. Like Auxin, Gibberellin is also an example of phytohormone.
70. A potted plant is growing in a transparent glass jar. In this plant, X and Y are the two growing parts having a lot of meristematic tissue. It is observed that the part X of this plant exhibits positive geotropism but negative phototropism. On the other hand, part Y of this plant exhibits negative geotropism but positive phototropism.
(a) Name the part X of plant.
(b) Name the part Y of plant.
(c) Which part of the plant, X or Y, will exhibit positive hydrotropism?
(d) Which part of the plant, X or Y, can have tendrils on it?
Answer
→ (a) Roots show positive geotropism and grow in the direction of gravity. In soil, they grow towards dark hence, show negative phototropism.
(b) Stem or shoot shows positive phototropism and grows towards the light. They grow in opposite direction of gravity hence, show negative geotropism.
(c) The plant roots (Part X) always move towards water hence shows positive hydrotropism.
(d) Tendrils grow towards a stimulus (touch) and show directional movement and represent thigmotropism. Stem (Part Y) can have tendrils on it.
71. There are three plants A, B and C. The flowers of plant A open their petals in bright light during the day but close them when it gets dark at night. On the other hand, the flowers of plant B open their petals at night but close them during the day when there is bright light. The leaves of plant C fold up and droop when touched with fingers or any other solid object.
(a) Name the phenomenon shown by the flowers of (i) plant A, and (ii) plant B.
(b) Name one flower each which behaves like the flower of (i) plant A, and (ii) plant B.
(c) Name the phenomenon exhibited by the leaves of plant C.
(d) Name a plant whose leaves behave like those of plant C.
(e) Which plant/plants exhibit the phenomenon based on growth movements?
Answer
→ (a) (i) Plant A shows positive photonasty.
(ii) Plant B shows negative photonasty.
(b) (i) In the morning, a dandelion flower opens up its petals in bright light. This phenomenon is known is positive photonasty.
(ii) A Moonflower flower closes its petals at night. This phenomenon is known as negative photonasty.
(c) Thigmonasty is the non-directional movement of a plant part in response to the touch. The folding up of leaves of plant C when touching is an example of this process.
(d) The folding up of Mimosa pudica leaves when touching is an example of Thigmonasty process.
(e) Plant A and B exhibit the phenomenon based on growth movements.
72. While conducting experiments to study the effect of various stimuli on the plants, it was observed that the roots of a plant X grow and bend towards two stimuli A and B but bend away from a third stimulus C. The stem of the plant X, however, bends away from stimuli A and B but bends towards the stimulus C. The stimulus B is known to act on the roots due to too much weight of the earth. Keeping these points in mind, answer the following questions:
(a) What could stimulus A be?
(b) Name the stimulus B.
(c) What could stimulus C be?
(d) The branches of a fallen tree in a forest grow straight up in response to two stimuli. What could be these two stimuli out of A, B and C? Also name these two stimuli.
Answer
→ (a) Stimulus A could be water as roots show the positive hydrotropism.
(b) Stimulus B could be gravity as roots show the positive geotropism.
(c) Stimulus C could be light as roots show the negative phototropism.
(d) The two stimuli could be B (gravity) and C (light).
73. P and Q are two types of plants having weak stems which cannot stand upright on their own. The plants P and Q have organs R and S respectively which can grow towards any support which they happen to touch and wind around that support. It is- observed that organ R originates from the leaves of the plant whereas organ S originates directly from the stem of the plant.
(a) What is (i) R, and (ii) S?
(b) What is the name of growth movement exhibited by the organs R and S?
(c) Name the stimulus involved in this case.
(d) State whether the behaviour of organs R and S is a tropic movement or a nastic movement.
(e) Name one plant like P and another plant like Q.
Answer
→ (a) (i) R is a leaf tendril.
(ii) S is a stem tendril.
(b) A tendril is a specialized leaf, petiole or stem with a threadlike shape. It is used by climbing plants for support and attachment. The tendrils grow towards the things they happen to touch and the phenomenon is known as thigmotropism.
(c) Touch (support) is the stimulus involved in this case.
(d) behaviour of organs R and S is a tropic movement. Tropic movement is always in the direction of stimulus. All parts of a plant (roots, stem and leaves etc.) exhibit tropic movements.
(e) Pea plant is like P (leaf tendrils) and bitter gourd plant is like Q (stem tendrils).
74. The top part A of the flask-shaped reproductive organ X in the flower of a plant secretes a surgery substance into its lower part B which goes towards the bottom part C of the flask-shaped organ. When a tiny grain D coming from the top part E of another reproductive organ Y in the flower falls on part A, it grows a long tube F through the organ X in response to the sugary substance and reaches the bottom part C of flask shaped organ to carry out fertilisation.
(a) What is (i) organ X, and (ii) organ Y, inside the flower?
(b) Name parts (i) A (ii) B, and (iii) C, of flask-shaped organ.
(c) Name (i) grain D, and (ii) part E of organ Y.
(d) Name the tube F.
(e) What is the phenomenon of growing a long tube in response to a sugary substance in the process of fertilization in a flower known as?
Answer
→ (a) (i) Inside the flower, the organ X is carpel (a female reproductive organ).
(ii) Inside the flower, the organ Y is stamen (a male reproductive organ).
(b) (i) Part A of flask shaped organ is stigma.
(ii) Part B of flask shaped organ is style.
(iii) Part C of flask shaped organ is ovary.
(c) (i) Grain D of organ Y (stamen) is pollen grain.
(ii) Part E of organ Y (stamen) is anther.
(d) Tube F is the pollen tube.
(e) Due to chemical stimulus, the growth of a plant part is known as chemotropism. For example, a sugary substance can induce to the growth of pollen tube towards the ovule. Here, sugary substance works as a stimulus and this process represents the positive chemotropism.
75. P, Q, R and S are four major types of phytohormones. P is a phytohormone which functions mainly as a growth inhibitor. It promotes the wilting and falling of leaves. Q, R and S are phytohormones which all promote growth of plants in various ways. Q is responsible for the phenomenon of phototropism in plants. R is involved mainly in shoot extensions. The phytohormone S helps in breaking the dormancy of seeds and buds. What are P, Q, R and S? Give one reason each for your choice.
Answer
→ P is abscisic acid (a plant growth inhibitor hormone) and is responsible for the wilting and falling of leaves. Q is auxin which is responsible for the phenomenon of phototropism in plants as it is present at shoot tip. R is gibberellin which is responsible for enlargement of shoot. S is cytokinin which is responsible for breaking the dormancy of seeds and buds.
76. A potted plant having straight parts A and B was placed horizontally on its side as shown in Figure (i). After a few days it was observed that the parts A and B of the plant acquire new positions as shown:
(a) Name the phenomenon exhibited by the position of plant parts A and B in Figure (ii)
(b) Name the stimulus (other than sunlight) which causes plant part A to grow and bend upwards, and plant part B to bend downwards.
Answer
→ (a) The position of plant parts A and B shows negative geotropism and positive geotropism respectively.
(b) Gravity is the stimulus which causes plant part A to grow and bend upwards, and plant part B to bend downwards.
77. When the leaves of a sensitive plant are touched with a finger, they fold up and when light fades at dusk, the petals of a dandelion flower close.
(a) State one way in which the above two processes are similar.
(b) State two ways in which the above two processes differ.
Answer
→ (a) Above mentioned processes are similar i.e. both are nastic movements.
(b) In first process of folding of leaves of sensitive plant (thigmonasty), the stimulus is touch but in second process of folding of petals of dandelion flower (photonasty), stimulus is light. First process (thigmonasty) is not a growth movement but second process (photonasty) is a growth movement.