What are the functions performed by the testis in human beings?
Testis are the primary sex organs in male reproductive system. It helps in maintaining the health of male body. sperm produces in seminiferous tubules, and also produces a hormone like androgen called testosterone and secrets inhibin protein. Testosterone is the male sex hormone helps in developing the male reproductive tissues like testis or prostate or in the growth of body muscles and hair.
Why is variation beneficial to the species but not necessarily for the individual?
Draw a labelled diagram of the longitudinal section of a flower.
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.
Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
How does the embryo get nourishment inside the mother’s body?
What is the importance of DNA copying in reproduction?
How does reproduction help in providing stability to populations of species?
What are the advantages of sexual reproduction over asexual 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?
The brain is responsible for
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.
What will happen if a solution of sodium hydrocarbonate is heated? Give the equation of the reaction involved.
How can you help in reducing the problem of waste disposal? Give any two methods.
Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4.
Why do ionic compounds have high melting points?
Which of the following pairs will give displacement reactions?
(a) NaCl solution and copper metal
(b) MgCl2 solution and aluminium metal
(c) FeSO4 solution and silver metal
(d) AgNO3 solution and copper metal.
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
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 do stars twinkle?
How does our body respond when adrenaline is secreted into the blood?