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Important Points to Remember in Chapter -1 - Control and Coordination from S.P. Sharma ESSENTIALS OF BIOLOGY CLASS X Solutions
1. Nervous system:
(i) The nervous system acts as the primary coordinating system in our body.
(ii) The process through which two or more organs interact and complement the function of one another is called coordination. Chemical coordination is seen in plants and animals.
(iii) The human nervous system is divided into the central nervous system and the peripheral nervous system.
2. Neuron:
(i) A neuron is a structural and functional unit of the nervous system with three distinct parts: cell body or cyton, dendrites, and axon.
(ii) Synapse is the junction between two neurons.
(iii) There are three types of neurons: sensory, motor, and interneuron.
3. Central Nervous System (CNS):
(i) The brain and spinal cord are the organs of the central nervous system.
(ii) The human brain and spinal cord are covered by three membraneous layers called meninges.
(iii) The human brain has three parts, the forebrain, midbrain, and hindbrain.
(iv) The cerebrum is the largest part of the brain.
(v) The spinal cord is enclosed within the vertebral column.
4. Peripheral Nervous System (PNS):
The peripheral nervous system consists of two types of nerves: cranial nerves and spinal nerves.
5. Autonomic Nervous System (ANS):
The autonomic nervous system has two divisions: the sympathetic and parasympathetic systems.
6. Reflex action:
(i) Reflex action is the body's rapid and involuntary response to a stimulus.
(ii) The neural pathway involved in a reflex action is called a reflex arc.
7. Plant growth regulators:
(i) Plants do not have a nervous system like animals but they do give response to environmental stimuli like light, touch, gravitational force, touch and chemicals, etc., in nature.
(ii) The growth and development in plants are regulated by a number of chemicals called plant growth regulators or plant hormones.
(iii) Plant hormones are very specific in action.
(iv) There are five main types of plant growth regulators. These are auxins, cytokinins, gibberellins, ethylene and abscisic acid.
(v) The growth regulators may promote or inhibit a process.
(vi) Auxins, cytokinins and gibberellins are plant growth promoters.
(vii) Ethylene and abscisic acid are plant growth inhibitors.
(viii) Ethylene is the only gaseous plant hormone.
8. Movement in Plants:
(i) The plants show movements in response to external stimuli and exhibit growth movements like bending, twisting, coiling, elongation, etc.
(ii) Plant movements in response to external stimuli can be broadly grouped into two categories: tropic movement or tropism and nastic movements.
(iii) Tropic movements could be in response to a stimulus like light, gravity, water, chemical or contact with the surface.
(iv) Phototropism, geotropism, hydrotropism, thigmotropism, and chemotropism are different tropic movements.
(v) Nastic movements are non-directional.
9. Hormones in animals:
(i) Endocrine glands are also called ductless glands and secrete chemical messengers, i.e., hormones.
(ii) Pituitary gland is the smallest but master endocrine gland.
(iii) Thyroid gland secretes thyroxine that controls the metabolism.
(iv) Pancreas consists of a group of hormone secreting cells called islets of Langerhans. Beta cells produce insulin.
(v) The deficiency of insulin causes Diabetes mellitus.
(vi) Oestrogen and Testosterone are the female and male hormones, respectively.
