Control and Coordination

NCERT Solution

Question 1: Which of the following is a plant hormone?

  1. Insulin
  2. Thyroxin
  3. Oestrogen
  4. Cytokinin
    Answer: (d) Ctyokinin

Question 2: The gap between two neurons is called a

  1. Dendrite
  2. Synapse
  3. Axon
  4. Impulse
    Answer: (b) Synapse

Chapter List

Question 3: The brain is responsible for

  1. Thinking
  2. Regulating the heart beat
  3. Balancing the body
  4. All of the above
    Answer: (d) All of the above

Question 4: What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?

Answer: Receptors provide information about the external environment so that the brain can instruct a related to organ to take necessary action. Receptors play an important role in our survival. Let us take the example of a person with hearing impairment. Certain ordinary task would be very difficult for that person. For example; while walking on the road, the person needs to hear the sound of vehicles moving near him. Without hearing those sounds, he would not be in a position to move safely on the road.

Question 5: Draw the structure of a neuron and explain its function.

Answer: Function of Neuron: Neuron transmits the nerve impulses.

structure of neuron

Question 6: How does phototropism occur in plants?

Answer: Concentration of auxin changes in a particular plant part, in response to the direction of light. For example; in a stem, concentration of auxin increases in those parts which are away from light. This increases cell division in that part and thus the stem bends towards light. That is how phototropism occurs in plants.

Question 7: Which signals will get disrupted in case of a spinal cord injury?

Answer: The spinal nerves go to the organs which are below the head region. Moreover, the autonomous nervous system is also connected to the spinal cord. In case of spinal cord injury, communication between the spinal nerves and the brain would be disturbed. Similarly, the communication between the autonomous nervous system and brain would also be disturbed; in case of spinal cord injury.

Question 8: How does chemical coordination occur in plants?

Answer: Plant hormones play their roles in chemical coordination. Most of the plant hormones promote growth in certain plant parts, e.g. auxin, gibberellins and cytokinin. Abscissic acid is a plant hormone which inhibits growth. Shedding of leaves or ripe fruits is facilitated by abscissic acid.

Question 9: What is the need for a system of control and coordination in an organism?

Answer: A living being does not live in isolation. It has to constantly interact with its external environment and has to respond properly for its survival. For example; when a hungry lion spots a deer, the lion has to quickly make a move so that it can have its food. On the other hand, the deer needs to quickly make a move to run for its life.

Question 10: How are involuntary actions and reflex actions different from each other?

Answer: Involuntary actions are part of routine activities, while reflex actions are in response to a sudden danger. Moreover, involuntary actions happen in involuntary organs, while reflex action happens in a voluntary organ.

Question 11: Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.

Answer: Nervous control is fast, while hormonal control is slow. Nervous control is facilitated by neurotransmitters, while hormonal control is facilitated by hormones.

Question 12: What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?

Answer: The movement in a sensitive plant is facilitated by chemical control, while the movement in our legs is facilitated by nervous control.

► YouTube Video

Copyright © excellup 2014