What are the major parts of the brain? Mention the functions of different parts.
Forebrain: It is composed of the cerebrum.
• Midbrain: It is composed of the hypothalamus.
• Hindbrain: It is composed of the cerebellum, pons and medulla oblongata.
Some main structures of the human brain are explained below.
(i) Cerebrum: The cerebrum is the largest part in the human brain. It is divided into two hemispheres; called cerebral hemispheres.
Functions of cerebrum:
(a) The cerebrum controls the voluntary motor actions.
(b) It is the site of sensory perceptions; like tactile and auditory perceptions.
(c) It is the seat of learning and memory.
(ii) Hypothalamus: The hypothalamus lies at the base of the cerebrum. It controls sleep and wake cycle (circadian rhythm) of the body. It also controls the urges for eating and drinking.
(iii) Cerebellum: Cerebellum lies below the cerebrum and at the back of the whole structure. It coordinates the motor functions. When you are riding your bicycle; the perfect coordination between pedaling and steering control is achieved by the cerebellum.
(iv) Medulla: Medulla forms the brain stem; along with the pons. It lies at the base of the brain and continues into the spinal cord. Medulla controls various involuntary functions; like heart beat, respiration, etc.
Write one example each of the following tropic movements :
(i) Positive phototropism (ii) Negative phototropism
(iii) Positive geotropism (iv) Negative geotropism
(v) Hydrotropism (vi) Chemotropism
What is the stimulus in : (a) phototropism ? (b) geotropism ? (c) chemotropism ? (d) hydrotropism ? (e) thigmotropism ?
What is chemotropism? Give one example. Name any two plant hormones and mention their functions.
What are 'hormones'? State one function of each of the following hormones:
(i) Thyroxine (ii) Insulin
Give one example each of a plant part:
(a) which is positively hydrotropic as well as positively geotropic.
(b) which is positively phototropic but negatively geotropic.
Name the plant part :
(a) which bends in the direction of gravity but away from light
(b) which bends towards light but away from the force of gravity
What does CNS stand for ? Which part of CNS : (a) consists of two cerebral hemispheres, and (b) has spinal nerves attached to it ?
(a) What is a reflex action ? Explain with the help of an example.
(b) Define reflex arc. Give the flow chart of a spinal reflex arc.
(c) How are involuntary actions and reflex actions different from each other ?
State how concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light ?
(i) Name the hormones that are released in human males and females when they reach puberty.
(ii) Name a gland associated with brain. Which problem is caused due to the deficiency of the hormone released by this gland ?
(a) Explain how auxins help in bending of plant stem towards light.
(b) State the objective of the experiment for which experimental set-up is shown in the given diagram.
A potted plant is made to lie horizontally on the ground. Which part of the plant will show
(i) positive geotropism?
(ii) negative geotropism?
What is a tendril ? Name the two types of tendrils. What does a tendril do in response to the touch of a support ? What is this phenomenon known as ?
a) What are the short fibres of a neuron known as ?
What is the long fibre of a neuron known as ?
Fill in the following blanks with suitable words :
(a) The two examples of effectors are…………. and………………
(b) Our…………. system allows Us to react to our surroundings. Information from receptors passes
along…………. neurons to our brain. Our brain sends impulses along………… neurons to our muscles.
(c) A neuron which carries an impulse to the brain is called a……………….
(d) The neuron which carries a message for action to a muscle or gland is known as a……………….
(a) What are the various sense organs in our body ?
(b) What is meant by receptors and effectors ? Give two examples of each.
(a) The human brain can be broadly divided into three regions. Name these three regions.
(b) What is cranium ? What is its function ?
(a) Name the structural and functional unit of nervous system.
(b) Draw a flow chart to show the classification of nervous system into various parts.
(c) What is autonomic nervous system ? What is its function ?
(d) What is voluntary nervous system ? Explain the working of voluntary nervous system with an example.
a) What is the function of our nervous system ?
(b) What are the main organs of the human nervous system ? Draw a labelled diagram to show the main organs of the human nervous system.
(c) How does the human nervous system work ? Explain.
Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in the given figure.
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?
What are meanings? What are their functions? Name the fluid, which is filled in between meanings.
Name the plant hormones which are responsible for the following effects :
(a) falling of leaves
(b) opening of stomata
(c) bending of stem towards light (d) closing of stomata
What is the name of in-built ‘arrangement’ in our body which controls the timing and amount of hormones released by various endocrine glands in the body ?