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1. (b) Yeast

2. (c) Vas deferens

3. (d) Pollen grains.

4. Sexual reproduction leads to variation due to recombination of genetic material
DNA. These variations are essential for survival of species. On the contrary, asexual
reproduction does not bring about variations.

5. In human beings, testes performs dual function:
 (i) Production of sperms
 (ii) Secretion of male hormone testosterone.

6. When in human female if the egg is not fertilized, it lives for about one day. Since the
ovary releases one egg every month, the uterus also prepares itself every month to
receive a fertilized egg. Thus, its lining becomes thick and spongy. This would be
required for nourishing the embryo if had fertilized. However, this lining is not
required any longer. So, the lining slowly breaks and comes out through the vagina
as blood and mucous. This cycle takes roughly every month and is known as
menstruation.

7.
 
8. Various methods used for regulation of child birth can broadly categories as:
(i) Barrier methods: In this method, physical devices such as condom, diaphragm,
cervical cap and copper-T are used.
(ii) Chemical method: use of spermicidal jelly by woman, oral pills and vaginal pills.
(iii) Surgical method: In surgical method, a small portion of vas deferens in male and
the oviduct of female, is surgically removed or ligated. It is called vasectomy in male
and Tubectomy in females.

9. In unicellular organisms, cell division, or fusion leads to the creation of new
individuals.
In multicellular organisms with simple body organization budding, fragmentation
may work but in complex multicellular organisms only sexual reproduction takes
place.

10. The consistency of DNA copying during reproduction is important for the
maintenance of body design features that allow the organism to use the particular
niche. Reproduction is, therefore, linked to the stability to populations of species.

11. The sexual act always has the potential to lead to pregnancy. Pregnancy will make
major demands on the body and the mind of the woman and if she is not ready for it,
her health will adversely affected. Therefore, adopting contraceptive methods are
essential. Some contraceptive methods like condom also prevent spread of STDs and
lethal diseases like HIV-AIDS.

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