What are the different methods of contraception?
There are three main methods of contraception :
1. Barrier methods: In barrier methods, physical devices such as condom, diaphragm and cervical caps are used. They prevent the entry Of sperms in the female genital tract during copulation.
2. Chemical methods: The chemical methods make use of specific drugs by females. There are two types of such drugs, Oral pills and vaginal pills. Oral pills are mainly hormonal preparation, and are called oral contraceptives (OCS).
3. Surgical methods: In the surgical methods, a small portion of vas deferens in male, and the fallopian tube in female, in surgically removed or ligated (tied). It is called vasectomy in males and tubectomy in females.
Apart from these three methods the intrauterine contraceptive devices are used to prevent pregnancies. The use of Intra Uterine Contraceptive Devices (IUCDs) is also very effective and popular. A copper-T is placed safely inside the uterus by a practising doctor or a skilled nurse. IUCDs prevent implantation in the uterus.
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?
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?
(a) Explain the terms:
(i) Implantation (ii) Placenta
(b) What is the average duration of human pregnancy?
List any four reasons for vegetative propagation being practised in the growth of some type of plants.
Explain vegetative propagation with the help of two examples. List two advantages of vegetative propagation.