Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the reverse?
When an electrical signal reaches the axonal end of a neuron, it releases a chemical substance. This chemical diffuses towards the dendrite end of next neuron where it generates an electrical impulse or signal. Hence, the electrical signal is converted into a chemical signal at the axonal end. Since these chemicals are absent at the dendrite end of the neuron the electrical signal, cannot be converted into chemical signal.
(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 ?
Fill in the following blanks :
(a) A plant’s response to light is called…………..
(b) A plant’s response to gravity is called…………..
(c) Plant shoot grows upward in response to…………….
(d) Plant roots grow downward in response to…………..
(e) Tendrils wind around a support in response to……………
(f) Plant roots grow towards…….. and in the direction of force of……………
(g) A root of a plant grows downward. This is known as…………..
(h) ……….is the hormone that causes phototropism in plants
(i) The response of leaves to the sunlight is called……………
Give the scientific terms used to represent the following :
(a) Bending of a shoot towards light.
(b) Growing of roots towards the earth.
(c) Growth of a pollen tube towards ovule.
(d) Bending of roots towards water.
(e) Winding of tendril around a support
What are the scientific names for the following receptors in animals ?
(a) receptors for light
(b) receptors for heat
(c) receptors for sound
(d) receptors for smell
(e) receptors for taste
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.
State the functions of any three of the structural and functional unit of nervous system.
(a) Name the two main constituents of the Central Nervous System in human beings.
(b) What is the need for a system of control and coordination in human beings?
Plant parts show two types of movements, one dependent on growth and the other independent of growth. Give one example of the movement in plant parts :
which depends on growth
which does not depend on growth
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 ?
Smita's father has been advised by a doctor to reduce his sugar intake.
(a) Draw the structure of neuron and label cell body and axon.
(b) Name the part of neuron:
(i) where information is acquired
(ii) through which information travels as an electrical impulse.
Which part of the brain controls involuntary actions? Write the function of any two regions of it.
Which of the following is a growth movement and which is not ?
(a) folding up of leaves of sensitive plant on touching with hand.
(b) folding up of petals of dandelion flower when light fades.
Name the plant organs which are :
(a) positively phototropic (b) positively geotropic
(c) negatively geotropic (d) positively hydrotropic
A person walks across a room in barefeet and puts his foot on a drawing pin lying on the floor. He lets out a cry. Explain what happens in his nervous system in bringing about this response.
Mention one function for each of these hormones:
(a) Thyroxin (b) Insulin (c) Adrenaline (d) Growth hormone (e) Testosterone.
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
(a) How is brain protected from injury and shock?
(b) Name two main parts of hind brain and state the functions of each.
What are 'hormones'? State one function of each of the following hormones:
(i) Thyroxine (ii) Insulin
A potted plant is made to lie horizontally on the ground. Which part of the plant will show
(i) positive geotropism?
(ii) negative geotropism?
Which one of the following actions on touch is an example of chemical control?
(i) Movement on the touch-sensitive plant.
(ii) Movement in human leg.
(a) What does a Mimosa pudica plant do in response to touch ? What is this phenomenon known as ?
(b) What happens to the dandelion flower (z) during daytime, and (ii) at night ? What is this phenomenon known as ?
(a) What is meant by ‘tropisms’ (or tropic movements) ? Explain with an example.
(b) What are the different types of tropisms ? Define each type of tropism. Write the name of stimulus in each case.
(c) How do tropisms differ from nasties (or nastic movements) ?
Which halogen element is necessary for the making of thyroxine hormone by the thyroid gland ?
Which one term in each of the following includes the other three ?
(a) thyroid, ductless gland, thymus, pituitary, ovary
(b) adrenalin, insulin, hormone, thyroxine, estrogen
(a) What substances are made by endocrine glands ?
(b) What is the function of receptors and effectors in our body ?
(a) Write the names of the regions in hindbrain. Give one function of each region.
(b) Name the functions of cerebrum.
(a) How does chemical coordination take place in human beings ?
(b) Why is the use of iodised salt advisable ?
What is the function of insulin hormone ? What type of patients are given insulin injections ?
Compare the nervous system and endocrine system (hormonal system) for control and coordination in humans.
State the functions of the following hormones :
(a) Thyroxine (b) Adrenaline (c) Growth hormone
In what ways are puberty and adolescence result of the activity of some glands in the human body ?
When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what the following are examples of :
(a) the smell of the food
(b) the cells in your nasal passages which perceive the smell
(c) the gland which is stimulated to secrete saliva.
(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 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 ?
