(a) Explain the role of placenta in the development of human embryo.
(b) Give example of two bacterial and two viral sexually transmitted diseases. Name the most effective contraceptive which prevents spread of such diseases.
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.
How are the modes for reproduction different in unicellular and multicellular organisms ?
List two advantages of practising vegetative propagation in plants. Select two plants raised by this method from the list given below:
Banana, Gram, Pea, Rose, Tomato, Wheat.
Differentiate between ‘self-pollination’ and ‘cross-pollination’. Describe double fertilisation in plants.
What is AIDS? Which microbe is responsible for AIDS infection? State one mode of transmission of this disease. Explain in brief one measure for the prevention of AIDS.
What is reproduction? What are its two types? Which one of the two confers new characteristics on the offsprings and how?
(a) Explain the role of placenta in the development of human embryo.
(b) Give example of two bacterial and two viral sexually transmitted diseases. Name the most effective contraceptive which prevents spread of such diseases.
Asexual reproduction takes place through budding in :
(a) Amoeba
(b) Yeast
(c) Plasmodium
(d) Leishmania.
What is the effect of DNA copying which is not perfectly accurate on the reproduction process?
“Variations that confer an advantage to an individual organism only will survive in a population.” Justify.
Write the full form of DNA. Name the part of the cell where it is located. Explain its role in the process of reproduction of the cell.
List the parts of human male reproductive system which contribute fluid to the semen. State two advantages semen offers to the sperms.
Name the two types of germ-cells present in human beings. How do they structurally differ from each other? Give two differences.
If a woman is using a copper-T will it help in protecting her from sexually transmitted diseases?
Explain the following methods of contraception giving one example of each:
(i) Barrier method
(ii) Hormonal imbalance method
(iii) Surgical method.
Describe in brief the role of (i) testis (ii) seminal vesicle, (iii) vas deferens, (iv) ureter and (v) prostate gland in human male reproductive system.
Draw a diagram of a human female reproductive system and label the part
(i) that produces egg
(ii) where fusion of egg and sperm take place
(iii) where zygote is implanted
What happens to human egg when it is not fertilised?
State in brief the changes that take place in a fertilised egg (zygote) till birth of the child in the human female reproductive system. What happens to the egg when it is not fertilised?
Name one sexually transmitted disease each caused due to bacterial infection and viral infection. How can these be prevented?
(a) In the human body what is the role of
(i) seminal vesicles, and (ii) prostate gland?
(b) List two functions performed by testis in human beings.
What is regeneration? State a reason why a more complex organism cannot give rise to new individuals through this method.
What are sexually transmitted diseases?
Name four such diseases. Which one of them damages the immune system of human body?
a) List any four reasons for adopting contraceptive methods.
(b) If a woman is using Copper-T, will it help in protecting her from sexually transmitted diseases? Why?
Which of the following is not a pan Of the female reproductive system in human beings ?
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube
(a) Name the parts labelled A, B, C, D and E.
(b) Where do the following functions occur?
(i) Production of an egg
(ii) Fertilisation
(iii) Implantation of zygote.
(c) What happens to the lining of uterus:
(i) before release of a fertilised egg?
(ii) if no fertilisation occurs?