- It is the center of intelligence, memory, emotions and imagination.
- It is responsible for the ordinary sensations like touch, pain, heat and cold and special sensations like sight hearing smell etc.
- It controls the functions of other parts of brain.
- It maintains equillibrum and controls the posture of body.
- It makes body movement smooth , stedy and coordinated.
- It also regulates and coordinates the contraction of skeletal muscles.
- It receives and integrates the impulses from spinal cord and sends resulting impulses to the cerebrum and cerebellum.
- It contains different centers that regulate heart beat rate, blood pressure, breathing, swallowing, salivation, sneezing etc. and other involuntary actions.
Cerebro spinal fluid:
- It protects the brain from jerks and shocks.
- It passes nutrients to spinal cord and brain and removes waste from there.
Hormones: Hormones are chemical substances secreted by endocrine glands.
Tropism: The directional movement of different parts of plant in response to external stimuli is called tropism.
Taxis: The movement of an organism as reaction in response to an external stimulus is called taxis.
1. When an earthworm is placed on the surface of soil, it tries to go into the soil.
Ans- When an earthworm is placed on the surface of soil, it tries to go into the soil for the reason that it shows positive geotaxis.
2. Hormones are called chemical messengers.
Ans- Hormones are called chemical messengers because these are carried to all body parts through blood circulation to bring about the harmonious working of the body.
3. Adrenal gland (adrenalin) is called emergency gland.
Ans- At the time of emergency, the secretion of hormone called adrenaline by adrenal gland prepare the body to meet of face any emergency conditions of emotional stress like fall in blood pressure, pain cold, injury, anger, fear etc. So adrenal gland (adrenaline) is called emergency gland.
4. When chloroform is brought near the tendrils of plant, the tendrils remain away from chloroform.
Ans- When chloroform is brought near the tendrils of plant, the tendrils remain away from chloroform because the tendrils show negative chemotropism with chloroform.
5. Pituitary gland is called master gland.
Ans- Pituitary gland controls and stimulates many activities of body and the secretion of other endocrine glands. So it is called master gland.
6. Roots of plant grow towards water.
Ans- Roots of plant grow towards water because the roots show positive hydrotropism.
7. Pancreas is called mixed gland.
Ans- As an exocrine gland, it produces pancreatic juice and as endocrine gland, it produces hormones like insulin. So pancreas is called mixed gland.
8. Sunflower opens during sunny day but jasmine opens during night only.
Ans- Sunflower shows positive photo-taxis but jasmine shows negative photo-taxis. So sunflower opens during sunny day and jasmine opens during night only.
9. Some adult women may develop facial hair.
Ans- Some adult women may develop facial hair due to the overgrowth of adrenal cortex.
10. Animals can respond quickly to a stimulus but plants cannot.
Ans- Plants do not have nervous system but use only endocrine system for co-ordination so plants cannot respond quickly to a stimulus but the animals do respond to a stimulus due to the presence of nervous system and endocrine system.