Class 10 Science - Chapter How do Organism Reproduce? NCERT Solutions | Why is variation beneficial to the speci

Draw a labelled diagram of the longitudinal section of a flower.

What are the functions performed by the testis in human beings?

Why does menstruation occur?

How will an organism be benefited if it reproduces through spores?

Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?

Asexual reproduction takes place through budding in

(a) amoeba.
(b) yeast.
(c) plasmodium.
(d) leishmania.

How does the embryo get nourishment inside the mother’s body?

What are the advantages of sexual reproduction over asexual reproduction?

What is the importance of DNA copying in reproduction?

How does reproduction help in providing stability to populations of species?

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?

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 person needs a lens of power –5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting (i) distant vision, and (ii) near vision?

Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other? Name this gas.

Why do acids not show acidic behaviour in the absence of water?

How are involuntary actions and reflex actions different from each other?

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?

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

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

Which of the following hydrocarbons undergo addition reactions: C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄.

Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?

You have two solutions, A and B. The pH of solution A is 6 and pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of this is acidic and which one is basic?