Class 10 Science - Chapter Control and Coordination NCERT Solutions | What is the need for a system of control

Draw the structure of a neuron and explain its function.

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?

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?

A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is (i) pushed into the coil, (ii) withdrawn from inside the coil, (iii) held stationary inside the coil?

Where should an object be placed in front of a convex lens to get a real image of the size of the object?

(a) At the principal focus of the lens
(b) At twice the focal length
(c) At infinity
(d) Between the optical centre of the lens and its principal focus.

A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Why is respiration considered an exothermic reaction? Explain.

What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Why do stars twinkle?

You are given kerosene, turpentine and water. In which of these does the light travel fastest? Use the information given in Table 10.3.

Fe₂O₃ + 2Al → Al₂O₃ + 2Fe

The above reaction is an example of a

(a) combination reaction.
(b) double displacement reaction.
(c) decomposition reaction.
(d) displacement reaction.

Explain the following.

(a) Why is the tungsten used almost exclusively for filament of electric lamps?
(b) Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
(c) Why is the series arrangement not used for domestic circuits?
(d) How does the resistance of a wire vary with its area of cross-section?
(e) Why are copper and aluminium wires usually employed for electricity transmission?

An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.