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प्रश्न
Give biological explanations for The placenta is an important structure for the development of a foetus
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उत्तर
The placenta allows diffusion of food and oxygen from mother to foetus and that of nitrogenous waste and CO2 from foetus to mother
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संबंधित प्रश्न
Given below are diagrams showing the different stages in the process of fertilisation of an egg. in the human female reproductive tract.
Study the diagrams and answer the questions:
1) Arrange the letters given below each diagram in a logical sequence to show the correct order in the process of fertilisation.
2) Where does fertilisation normally take place? and What is ‘Implantation’ that follows fertilisation?
3) Mention the chromosome number of the egg and zygote in humans.
4) Explain the term ‘Gestation’. How long does Gestation last in humans?
5) Draw a neat, labelled diagram of a mature human sperm.
What are the male sex cells in humans called?
Which part of the human body passes sperms from a man to a woman?
Write the names of male sex hormone?
When a human female reaches a certain age then vaginal bleeding occurs for a few days after regular time intervals.
(a) What is this process known as (i) in scientific terms, and (ii) in everyday language?
(b) At what approximate age this process starts in human females? When is the human female said to have attained at this stage?
(c) After how much time is this process repeated? For how many days does this process usually last?
(d) What does the onset of this process in human females signify?
(e) At which particular event in the life of a human female does this process stop temporarily but start again?
(f) At which approximate age of human female does this process stop permanently?
Identify the given diagram.
Name the parts 1 to 5. 
Name the Following
What does this abbreviation stand for LH?
Mention the importance of the position of the testes in humans.
Which one of the following statements about human sperm is correct?
Given below is a group of terms. In the group, one pair indicates the relationship between the two terms. Rewrite and complete the second pair on a similar basis.
Female gonad : Ovaries :: Male gonad : ______.
