Class 10 Science - Chapter Heredity and Evolution NCERT Solutions | What evidence do we have for the origin

Outline a project which aims to find the dominant coat colour in dogs.

How is the sex of the child determined in human beings?

A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?

How do Mendel’s experiments show that traits are inherited independently?

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?

Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?

Explain the terms analogous and homologous organs with examples.

How do Mendel’s experiments show that traits may be dominant or recessive?

How does the creation of variations in a species promote survival?

Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?

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 difference between a reflex action and walking?

What is the importance of DNA copying in reproduction?

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?

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?

Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.

What is hydrogenation? What is its industrial application?

How are the lungs designed in human beings to maximise the area for exchange of gases?

A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R′, then the ratio R/R′ is –

(a) 1/25        (b) 1/5        (c) 5        (d) 25

Differentiate between metal and non-metal on the basis of their chemical properties.

Why are carbon and its compounds used as fuels for most applications?

What will happen if we kill all the organisms in one trophic level?

Butanone is a four-carbon compound with the functional group

(a) carboxylic acid.
(b) aldehyde.
(c) ketone.
(d) alcohol.