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?
How does our body respond when adrenaline is secreted into the blood?
Which part of the brain maintains posture and equilibrium of the body?
What are plant hormones?
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?
An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be –
(a) 100 W (b) 75 W (c) 50 W (d) 25 W
Name some sources of direct current.
Why should we conserve forests and wildlife?
We saw in this chapter that there are four main stakeholders when it comes to forests and wildlife. Which among these should have the authority to decide the management of forest produce? Why do you think so?
Why does the Sun appear reddish early in the morning?
What is the far point and near point of the human eye with normal vision?
Why do you think that there should be equitable distribution of resources? What forces would be working against an equitable distribution of our resources?
What will be the formula and electron dot structure of cyclopentane?
Give an example of a metal which
(i) is a liquid at room temperature.
(ii) can be easily cut with a knife.
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat.
Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.