Class 10 Science Chapter 6 Question Answers - Control and Coordination

Q1: Define ‘reflex action’.  
Ans: It is an automatic, spontaneous, and immediate involuntary response to a stimulus controlled usually by the spinal cord. e.g. knee jerk movement.

Q2: Name the largest cell in the human body.  
Ans: Nerve cell (Neuron).

Q3: Give an example of a plant hormone that promotes growth. 
Ans: Auxin.

Chemical structure of AuxinQ4: What are plant hormones?  
Ans: The chemical substances produced in plants that help in the growth and development of the plant, its tissues, and other plants.

Q5: Name the part of neuron  
(а) where information is acquired.
(b) through which information travels an electrical impulse.
Ans: (a) Dendrite
(b) Axon

Q6: Name two tissues that provide control and coordination in multicellular animals.  
Ans: Muscular tissues and nervous tissue.

Q7: Name the hormone, the secretion of which is responsible for dramatic changes in appearance in girls and boys when they approach 10-12 years of age.  
Ans: Testosterone is released from the testes in males, and estrogen is released from ovaries in females.

Q8: Name the hormone that helps regulate the level of sugar in our blood. Name the glands that secrete it.
Ans: Insulin hormone secreted by the pancreas.

Q9: Name a plant hormone that inhibits growth. Write one more function.  
Ans: Abscisic acid inhibits growth in plants. It also causes the closure of stomata during water stress.

Q10: A potted plant is made to lie horizontally on the ground. Which part of the plant will show:
(i) Positive geotropism
(ii) Negative geotropism  
Ans:
(i) Roots will show positive geotropism.
(ii) Shoots will show negative geotropism.

Q11: Name a plant hormone that promotes growth in plants.  
Ans: Auxin is a plant hormone that promotes growth and cell elongation in plants.

Q12: State one function of each of the pons and cerebellum.
Ans: Pons: Regulates rate of respiration
Cerebellum: Maintains equilibrium of the body during walking, jumping, etc.

Q13: Name a gaseous plant hormone. Give its role.
Ans: Ethylene is a gaseous hormone. It regulates fruit ripening.

Q14: How many spinal and cranial nerves are present in the human body?
Ans: Spinal nerves = 31 pairs
Cranial nerves = 12 pairs

Q15: What are meninges?
Ans: The three membranes that cover the brain to protect it are called meninges.

Q16: Define Reflex Arc.
Ans: The reflex arc is the route traversed by nerve impulses during a reflex action, moving from a receptor organ, which may be a sense organ like the eyes or skin, to the spinal cord and subsequently back to the effector organ, which could be muscles or glands. 

Q17: Draw a neat diagram of a neuron.
Ans: 
Structure of a NeuronQ18: State one example of chemotropism.  
Ans: The chemotropism observed in the fertilization process of a flower involves the growth of the polleState the two types of movements seen in plants n tube towards the ovule in response to a chemical stimulus. 

Q19: State the two types of movements seen in plants.
Ans:
(i) Nastic Movements.
(ii) Tropic Movements or Tropism.

Q20: Define phototropism.
Ans: Phototropism is the plant's response to light, with shoots exhibiting positive phototropism by growing towards the light, and roots showing negative phototropism by growing away from light.