HOW DO ORGANISM REPRODUCTION
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Question.40 State one
genetically different feature between sperms and eggs of humans. What is its consequence?
Answer. The sex chromosome of human male is XY. A sperm of human
male carries either an X chromosome or one Y chromosome.
The sex chromosome of human female is XX and hence, the egg always carries the
X chromosome.
If a sperm carrying X chromosome fertilises an egg which carries X chromosome,
then the’ child born will be a girl. If a sperm
carrying Y chromosome fertilises an egg which carries X chromosome, then the
child born will be a boy.
Name the most
effective contraceptive which prevents spread of such diseases.
Answer.
(a) Role of placenta in the development of human embryo: A special tissue
develops between the uterine wall and the embryo (foetus) called placenta,
where exchange of nutrients, glucose and oxygen takes place. The developing
embryo will also generate waste substances which can be removed by transferring
them into the mother’s blood through the placenta. The development of the child
inside the mother’s blood takes approximately nine months.
(b) Sexually transmitted diseases (STDs) transmitted by bacteria are:
(i) Gonorrhoea (ii) Syphilis
STDs transmitted by virus:
(i) AIDS (ii) Genital warts
The most effective contraceptive which prevents the spread of these diseases is
by the use of mechanical barriers such as physical devices like condoms.
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