Draw the structure of a neuron and explain its function.
Nervous system controls and coordinates the activities, bevahiour of animals, also maintains the homeostasis (internal body temperature) & is composed of two principal cells:-
Neurons (nerve cells)
Neuroglia or glial cells
Neurons:- These are the basic structural & functional unit of nervous system. They are specialized to respond to stimulus (any change in envirionment ,i.e, strong enough to initiate an nerve impulses) can be physical or chemical, conduct nerve impulses and release chemicals called neurotransmitters.
Nerve impulses travels at the speed ranges from 0.5 to 130 meters per second along plasma membrane of a neuron.
Neroglia cells or glial cells (glia-glue) :- These cells nourishes, protects and support the neurons.
Which signals will get disrupted in case of a spinal cord injury?
How does chemical coordination take place in animals?
Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Why is the use of iodised salt advisable?
The brain is responsible for
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.
How do we detect the smell of an agarbatti (incense stick)?
How do auxins promote the growth of a tendril around a support?
Which part of the brain maintains posture and equilibrium of the body?
How does our body respond when adrenaline is secreted into the blood?
What is the need for a system of control and coordination in an organism?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
What is a good source of energy?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?
Explain different ways to induce current in a coil.
Why does the Sun appear reddish early in the morning?
Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?
The human eye forms the image of an object at its
(a) cornea. (b) iris. (c) pupil. (d) retina.
In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic numbers 12, 19, 21 and 38. Which of these have physical and chemical properties resembling calcium?
A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?
An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focussed image can be obtained? Find the size and the nature of the image.
How do Mendel’s experiments show that traits are inherited independently?
A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.