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.
The full form of DNA is deoxyribonucleic acid. It is the genetic material found in the chromosomes, which are present in the nucleus of a cell.
Role of DNA in the process of repro ¬duction of the cell:
DNA plays an important role in the reproduction of a cell. The reproducing cell produces an identical copy of DNA through some cellular mechanism. Since the newly formed copy of DNA lacks an organised cellular structure, the cell gets divided to provide cell cover to the newly formed DNA. Thus, two daughter cells are formed from the single cell as a result of the copying of DNA.
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 the effect of DNA copying which is not perfectly accurate on the reproduction process?
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.
Name one sexually transmitted disease each caused due to bacterial infection and viral infection. How can these be prevented?
Draw a longitudinal section of a flower and label the following parts:
(i) Part that produces pollen grain.
(ii)Part that transfers male gametes to the female gametes.
(iii) Part that is sticky to trap the pollen grain.
(iv) Part that develops into a fruit.
What is reproduction? What are its two types? Which one of the two confers new characteristics on the offsprings and how?
Explain the following methods of contraception giving one example of each:
(i) Barrier method
(ii) Hormonal imbalance method
(iii) Surgical method.
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?
“Variations that confer an advantage to an individual organism only will survive in a population.” Justify.
(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.
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.
Name the two types of germ-cells present in human beings. How do they structurally differ from each other? Give two differences.
(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?
What are sexually transmitted diseases?
Name four such diseases. Which one of them damages the immune system of human body?
“DNA copies generated during reproduction will be similar but may not be identical to the original.” Justify this statement.
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?
If a woman is using a copper-T will it help in protecting her from sexually transmitted diseases?
(a) Explain the terms:
(i) Implantation (ii) Placenta
(b) What is the average duration of human pregnancy?
Explain vegetative propagation with the help of two examples. List two advantages of vegetative propagation.
(a) What is fragmentation in organism?
Name a multicell-ular organism which reproduces by this method.
(b) What is regeneration in organism? Describe regeneration in Planaria with the help of a suitable diagram.
Name an organism which reproduces by spore formation. List three conditions favourable for spores to germinate and grow.
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.
List any four reasons for vegetative propagation being practised in the growth of some type of plants.