Class 10 Science - Chapter How do Organism Reproduce? NCERT Solutions | Can you think of reasons why more comple

Why is variation beneficial to the species but not necessarily for the individual?

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?

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?

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

Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.

Which of the following constitute a food-chain?

(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat

At the time of short circuit, the current in the circuit

(a) reduces substantially.
(b) does not change.
(c) increases heavily.
(d) vary continuously.

How is oxygen and carbon dioxide transported in human beings?

Translate the following statements into chemical equations and then balance them.

(a) Hydrogen gas combines with nitrogen to form ammonia.
(b) Hydrogen sulphide gas burns in air to give water and sulpur dioxide.
(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.

Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 Ω resistor, an 8 Ω resistor, and a 12 Ω resistor, and a plug key, all connected in series.

The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below –

I (amperes)   0.5   1.0   2.0   3.0    4.0
V (volts)        1.6   3.4   6.7   10.2  13.2

Plot a graph between V and I and calculate the resistance of that resistor.

Define the principal focus of a concave mirror.

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.