. Write the function of placenta in human females

.(a) Write  the function of placenta in  human females.


(b) List four ways of preventing pregnancy. State two advantages of using such preventive methods

Best Answer

(a) The exchange of nutrients, oxygen  and  waste  products between the embryo and  the mother  takes  place through placenta


(b) Methods to prevent pregnancy


(i) Barrier methods. In these methods, physical devices such as condoms, diaphragm and cervical caps are used. These devices prevent the entry of sperm in the female genital tract, thus acting as a barrier between them


(ii) Surgical methods. There are surgeries that can be carried out in males and females. In males, a small portion of the sperm duct (vas deferens) is blocked by surgical operation. It prevents the egg to reach the uterus. In both the cases, fertilization will not take place


(iii)  Chemical methods. This category of contraceptives  acts by changing  the hormonal balance  of the  body  so  that  eggs  are  not  released  and  fertilization  cannot  occur. Females use two types of pills for preventing pregnancies, i.e., oral pills and vaginal pills. The oral pills contain hormones which stop the ovaries from releasing ovum into fallopian tube. This is also called oral contraceptives (OC)


Other  contraceptive  device such  as loop  or  the copper-T  are  placed  in  the  uterus  to prevent  pregnancy


Advantages  of using preventive methods


(i) Contraceptive methods   are   used    to   prevent   the   spreading of   sexually transmitted diseases like syphilis, AIDS etc


(ii) Contraceptive methods are also used to control human population by checking the unwanted pregnancies during sexual activities

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