What could be the reasons for adopting contraceptive methods?
There can be many reasons for adopting contraceptive methods:-
The main reason for adopting the contraceptive methods is birth control or the population control.
Condoms are the safeguard against the infection of AIDS (acquired immune deficiency syndrome) or STD (sexually transmitted diseases)
The induced abortion method of contraception is used to get rid of unwanted pregnancy by the unprotected intercourse, when women get raped by someone, or where mother’s life or foetus is in danger and when women is not able to conceive the baby due to the weak immune system of the baby.
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?
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.
What are the advantages of sexual reproduction over asexual reproduction?
How does the embryo get nourishment inside the mother’s body?
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?
Why does a compass needle get deflected when brought near a bar magnet?
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 a normal eye not able to see clearly the objects placed closer than 25 cm?
State whether the following statements are true or false.
(a) An electric motor converts mechanical energy into electrical energy.
(b) An electric generator works on the principle of electromagnetic induction.
(c) The field at the centre of a long circular coil carrying current will be parallel straight lines.
(d) A wire with a green insulation is usually the live wire of an electric supply.
Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.
What is the role of the split ring in an electric motor?
Name two safety measures commonly used in electric circuits and appliances.
What are the components of the transport system in highly organised plants?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What can you as an individual do to reduce your consumption of the various natural resources?