Page 130 - NCERT Science Class 10 English Medium

We must also consider the possible health consequences of having
sex. We have discussed in Class IX that diseases can be transmitted
from person to person in a variety of ways. Since the sexual act is a
very intimate connection of bodies, it is not surprising that many
diseases can be sexually transmitted. These include bacterial infections
such as gonorrhoea and syphilis, and viral infections such as warts
and HIV-AIDS. Is it possible to prevent the transmission of such diseases
during the sexual act? Using a covering, called a condom, for the penis
during sex helps to prevent transmission of many of these infections to
some extent.
The sexual act always has the potential to lead to pregnancy.
Pregnancy will make major demands on the body and the mind of the
woman, and if she is not ready for it, her health will be adversely
affected. Therefore, many ways have been devised to avoid pregnancy.
These contraceptive methods fall in a number of categories. One
category is the creation of a mechanical barrier so that sperm does not
reach the egg. Condoms on the penis or similar coverings worn in the
vagina can serve this purpose. Another category of contraceptives acts
by changing the hormonal balance of the body so that eggs are not
released and fertilisation cannot occur. These drugs commonly need
to be taken orally as pills. However, since they change hormonal
balances, they can cause side-effects too. Other contraceptive devices
such as the loop or the copper-T are placed in the uterus to prevent
pregnancy. Again, they can cause side effects due to irritation of the
uterus. If the vas deferens in the male is blocked, sperm transfer will
be prevented. If the fallopian tube in the female is blocked, the egg will
not be able to reach the uterus. In both cases fertilisation will not take
place. Surgical methods can be used to create such blocks. While
surgical methods are safe in the long run, surgery itself can cause
infections and other problems if not performed properly. Surgery can
also be used for removal of unwanted pregnancies. These may be
misused by people who do not want a particular child, as happens in
illegal sex-selective abortion of female foetuses. For a healthy society,
the female-male sex ratio must be maintained. Because of reckless
female foeticides, child sex ratio is declining at an alarming rate in
some sections of our society, although prenatal sex determination has
been prohibited by law.
We have noted earlier that reproduction is the process by which
organisms increase their populations. The rates of birth and death in a
given population will determine its size. The size of the human population
is a cause for concern for many people. This is because an expanding
population makes it harder to improve everybody’s standard of living.
However, if inequality in society is the main reason for poor standards of
living for many people, the size of the population is relatively unimportant.
If we look around us, what can we identify as the most important
reason(s) for poor living standards?

How do Organisms Reproduce? 125

2024-25