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?
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.
How does the embryo get nourishment inside the mother’s body?
What are the advantages of sexual reproduction over asexual reproduction?
How does reproduction help in providing stability to populations of species?
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?
Use the data in Table 12.2 to answer the following –
(a) Which among iron and mercury is a better conductor?
(b) Which material is the best conductor?
What are the advantages of nuclear energy?
The magnification produced by a plane mirror is +1. What does this mean?
What are the different ways in which glucose is oxidised to provide energy in various organisms?
What happens at the synapse between two neurons?
Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
How are the lungs designed in human beings to maximise the area for exchange of gases?
Fe2O3 + 2Al → Al2O3 + 2Fe
The above reaction is an example of a
(a) combination reaction.
(b) double displacement reaction.
(c) decomposition reaction.
(d) displacement reaction.
Which signals will get disrupted in case of a spinal cord injury?
Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.