Describe sexually transmitted diseases and mention the ways to prevent them.
Disease that spreads from person to person through sexual intercourse with the infected person is known as Sexually transmitted diseases (STD S ) or venereal diseases (VD) or reproductive tract Infection (RTI). This leads to various diseases like HIV leading to AIDS (acquired immunodeficiency syndrome), gonorrhoea, syphilis, genital herpes, hepatitis- B.
Preventions:-
1. One must avoid sexual intercourse with an unknown person or multiple persons.
2. Use condoms or other contraceptive methods during intercourse.
3. If you have any doubt, one must consult a qualified doctor without delay.
4. Avoid sharing of trimmers, razors, towels and underclothing.
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?
What is the importance of DNA copying in reproduction?
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 solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains
(a) NaCl (b) HCl (c) LiCl (d) KCl
The kidneys in human beings are a part of the system for
(a) nutrition. (c) excretion.
(b) respiration. (d) transportation.
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?
Why does the Sun appear reddish early in the morning?
Define the principal focus of a concave mirror.
Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Compare and contrast bio-mass and hydro electricity as sources of energy.
A spherical mirror and a thin spherical lens have each a focal length of –15 cm. The mirror and the lens are likely to be
(a) both concave.
(b) both convex.
(c) the mirror is concave and the lens is convex.
(d) the mirror is convex, but the lens is concave.
Which of the following groups contain only biodegradable items?
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass
A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?