Control and Coordination
One Marks Questions
Answer: Neuron
Answer: Fore brain.
Answer: Iodine stimulates the thyroid gland to produce thyroxin hormone. Deficiency of this hormone results in the enlargement of the thyroid gland. This can lead to goitre.
Answer:
(i) Gustatory receptors – these are sensitive to taste.
(ii) Olfactory receptors – these are sensitive to smell.
Answer: Cerebellum in hind-brain controls the posture and balance of the body.
Answer:
Involuntary action including blood pressur salivation vomiting are controlled by medulla in the hind brain.
Answer: The growth of pollen tube toward ovule.
Answer: Plant hormone that promotes growth is auxin.
Answer: Plant hormone that inhibits growth is Abscisic acid.
Answer: Testosterone in male. Oestrogen in female.
Answer: Spinal cord is enclosed in a bony cage called vertebral column.
Two Marks Questions
Answer: A synapse is the gap between the two neurons. At synapse the electrical signals converted into chemicals, that can easily cross over the gap and pass on to the next neurons where it again converted into electrical signals.
Answer:
An involuntary action by human body parts in respons to a stimulus is called reflex action.
It helps us in protecting us from sudden stimulus which may harm us.
Answer:
CNS – Brain and Spinal chord
PNS - Cranial nerves and Spinal nerves
Answer:
When growing plants detect light auxin synthesized at the shoot tip,helps the cell to grow longer.When light is coming from one side of the plant auxin diffuses towards the shady side of the shoot.This concentration of auxin stimulates the cell to grow longer on the side of the shoot which is away from light.Thus the plant appears to bend towards light.
Answer: When a tendril comes in contact with a support, auxin diffuses towards the opposite side of the shoot , auxin stimulates faster growth of the cells on the opposite side that's why the tendril forms a coil around the support.
Answer:
When the sugar level in blood increases, it is detected by the a-cells of the pancreas which responds by producing more insulin. As the blood sugar level falls, insulin secretion is reduced.
Three Marks Questions
Answer:
1. End of the dendritic tip of a nerve cell.
2. Electrical impulses travels from the dendrites to the cell body,and then along the axon to its end.
3. Synapsis.
Answer:
Phototropism: movement of plant towards or away from the light.
Eg:Shoots respond by bending towards light while roots respond by bending away from light.
Geotropism: movement of plant parts towards the earth or away from it.
Rootsof plant always grow downwords while shoots usually grow upward and away from the earth.
Hydrotropism: movement of plant parts towards or away from any source of water.
Roots of plant always grow towords water while shoots usually grow upward and away from the water.
Answer:
* Heart beats faster, resulting in supply of more oxygen to our muscle.
* The blood to the digestive system and skin is reduced due to contraction of muscles around small arteries in these organs.This diverts the blood to our skeletal muscles.
* The breathing rate also increases because of concentration of the diaphragm and the rib muscle.
Answer:
1. He is suffering from diabetes.
2. Deficiency of insulin causes diabetes.
3. Pancreas secretes insulin.
Answer:
a. Pitutary gland
b. Stimulates growth in all organs
c. Dwarfism
Four Marks Questions
Answer:
Three endocrine glands with their function in human body are as follows:
1. Thyroid gland: It secretes a hormone called thyroxine which regulates the metabolism of carbohydrates, fats and proteins in the body and so provide the best balance for nutrients and mental ability.
2. Adernal gland: It secretes two hormones—adrenalin and corticoid hormones regulate blood pressure, heartbeat, breathing rate and carbohydrate metabolism.
3. Pancreas: It secretes two hormones—insulin and glucagon. Insulin hormone lowers the blood glucose level. Glucagon hormone increases the blood glucose level.
Answer:
(a) Brain is covered by a three layered membrane called meninges. In between the layers of meninges and brain, cavity fluid named Cerebro Spinal Fluid (CSF) is filled. The hard skull covers the meninges. Thus Meninges, CSF and Skull protects our brain for a certain extent.
(b) Two main parts of hind-brain are — Medulla and Cerebellum. Their functions are
Medulla : Involuntary actions such as blood pressure, salivation and vomiting.
Cerebellum : It is responsible for precision of voluntary actions and maintaining the posture and balance of the body.
Answer:
Refex arch is neural pathway which controls reflex action.
1. Receptor organ perceives the stimulus and activates a sensory nerve impulse.
2. Sensory nerve carries message in the form of sensory impulse to the spinal cord.
3. The spinal cord acts as modulator : The neurons of spinal cord transmit the sensory nerve impulse to motor neuron.
4. Motor never conducts these impulses to the effectors muscles which responds to the stimulus.
Answer:
Four different types of plant hormones are
Auxins, Gibberellins, Cytokinins, Abscisic acid.
1. Auxins :Helps the cell to grow longer.Promote the bending of stem towards the light.Promote the growth of a tendril around a support.
2. Gibberellins :Helps in growth of stem.
3. Cytokinins :Promote cell division,such as in fruits and seeds.
4. Abscisic acid inhibits the growth of the plant body including wilting of leaf.
Answer:
1. Goitre
2. Swollen neck
3. Thyroxine
4. Thyroid gland
5. Iodine
