NCERT Exemplar Class 10 Science Solutions

Chapter 07-Control and Coordination-Short Answers

Short Answer Type Questions
Q.34. Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in given figure.

 

Answer.
a) Sensory neuron
b) Spinal cord (CNS)
c) Motor neuron
d) Effector (muscle in arm)
Direction of flow of electric signal is as shown below:
Sensory receptor → sensory neuron → spinal cord (CNS) → motor neuron → effector organ

Q.35. Name the plant hormones responsible for the following:
a) Elongation of cells
b) Growth of stem
c) Promotion of cell division
d) Falling of senescent leaves
Answer.
a) Elongation of cells: Auxin
b) Growth of stem: Gibberellin
c) Promotion of cell division: Cytokinin
d) Falling of senescent leaves: Abscisic acid

Q.36. Label the endocrine gland in figure:

Answer.
a) Pineal gland
b) Pituitary gland
c) Thyroid gland
d) Thymus gland
Q.37. In figure (a), (b) and (c), which appears more accurate and why?

 

Answer.
Figure (a) is more accurate. Roots of plants are positive geotropic and grow downwards while stem is positive phototropic and grows upward.
Q.38. Label the part of a neuron in figure given below.

 

Answer.
a) Dendrite
b) Cell body
c) Axon
d) Nerve ending
Q.39. Match the terms of Column (A) with those of Column (B)

 

Answer.
The matching of the column (A) with column (B) is:

 

Q.40. What is a tropic movement? Explain with an example.
Answer. The directional growth movements of plants due to an external stimuli are called tropic movements. It can be either towards the stimulus, or away from it.
Growth of plant in response to light is known as phototropism. For example, shoots and stem of the plant grow upwards hence show positive phototropism.
Growth of of plant in direction of gravity is known as geotropism. For example, roots of plants are grow downwards hence show positive geotropism.

Q.41. What will happen if intake of iodine in our diet is low?
Answer. Thyroid gland produces thyroxine and triiodothyronine. Thyroxine has four iodine atoms, while triiodothyronine has three iodine atoms. The dietary iodine serves as source and thus iodine deficient diet renders the gland unable to synthesize the hormones. Thyroid hormones deficiency inhibits metabolic rate, growth and development.
A person might suffer from goitre in case of iodine deficiency in the body.
Q.42. What happens at the synapse between two neurons?
Answer.Synapse is the junction between two neurons. Electrical impulse at the axonal end stimulates the axon bulb to release chemical (neurotransmitter) which in turn diffuses across the synapse. The chemical serves to stimulate the dendrites of adjacent neuron which in turn send electrical signals to their cell body to be carried along the axon.
Q.43. Answer the following:
a) Which hormone is responsible for the changes noticed in females at puberty?
b) Dwarfism results due to deficiency of which hormone?
c) Blood sugar level rises due to deficiency of which hormone?
d) Iodine is necessary for the synthesis of which hormone?
Answer.
a) Oestrogen is responsible for development of secondary sexual characters in females at puberty.
b) Growth hormone promotes growth and development of the body.
c) Insulin controls blood sugar level by stimulating oxidation of glucose and absorption of glucose by liver and muscle cells.
d) Iodine is necessary for the synthesis of thyroxine. It is a thyroid hormone that regulates the metabolism in the body.
Q.44. Answer the following:
a) Name the endocrine gland associated with brain?
b) Which gland secretes digestive enzymes as well as hormones?
c) Name the endocrine gland associated with kidneys?
d) Which endocrine gland is present in males but not in females?
Answer.
a) Pituitary gland located in the groove of sphenoid bone of the skull in the brain.
b) Pancreas secretes the pancreatic juice and hormones insulin and glucagon.
c) Adrenal glands are located on the top of two kidneys.
d) Testes are present only in males which secrete male sex hormone, testosterone.