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प्रश्न
Give biological explanations for All the food chains begin with green plants.
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उत्तर
Green plants are the only organisms that are able to synthesize food from CO2 and H2O in presence of chlorophyll and sunlight. However, animals depend upon plants for food. Therefore, all food chains begin with green plants
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संबंधित प्रश्न
Name the human male reproductive organ that produces sperms and also secretes a hormone. Write the functions of the secreted hormone.
Describe, in brief, the changes the uterus undergoes
(i) to receive the zygote.
(ii) if zygote is not formed
What could be the reasons for adopting contraceptive methods?
Describe in brief the structure of placenta
When a female child is born, her ovaries already contain thousands of immature eggs (or ova) contained in immature structures A. On maturing, A bursts open and an egg shoots out of the ovary in a process called B. The process B starts in the females at puberty and occurs again and again after a time period x. Before every occurrence of process B, the inner lining of uterus becomes thick and soft with lots of blood vessels in it. When the egg cell gets fertilised by a sperm, then an event C occurs in the life of mature human female which lasts for time period y leading to the birth of baby. If, however, the egg cell released by the ovary does not get a sperm to fuse with, then the thick and soft inner lining of uterus breaks down and comes out of the female's body in an event called D. The occurrence of event D is controlled by chemical substances E.
(a) What are A?
(b) What is process B?
(c) What is the time period x?
(d) Name the event C.
(e) How much is the time period y?
(f) What is the name of process D?
(g) Name the chemical substances E.
Mention the two functions of human testis.
Explain how the sex of the child is determined at the time of conception in human beings.
Define the following:
Gestation
Define the four stages in the uterine cycle.
What is the composition of semen?
