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.
What is the effect of DNA copying which is not perfectly accurate on the reproduction process?
(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.
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) 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?
Name one sexually transmitted disease each caused due to bacterial infection and viral infection. How can these be prevented?
Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
How are the modes for reproduction different in unicellular and multicellular organisms ?
What is reproduction? What are its two types? Which one of the two confers new characteristics on the offsprings and how?
State one genetically different feature between sperms and eggs of humans. What is its consequence?
List any four reasons for vegetative propagation being practised in the growth of some type of plants.
“DNA copies generated during reproduction will be similar but may not be identical to the original.” Justify this statement.
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.
(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.
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 does HIV stand for? Is AIDS an infectious disease? List any four modes of spreading AIDS.
(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.
(a) Explain the terms:
(i) Implantation (ii) Placenta
(b) What is the average duration of human pregnancy?
Explain the following methods of contraception giving one example of each:
(i) Barrier method
(ii) Hormonal imbalance method
(iii) Surgical method.
Differentiate between ‘self-pollination’ and ‘cross-pollination’. Describe double fertilisation in plants.
“Variations that confer an advantage to an individual organism only will survive in a population.” Justify.
Illustrate the following with the help of suitable diagrams:
(i) Regeneration in Planaria.
(ii) Budding in Hydra.
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.
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?