Very Short Answer Questions - 1 Mark

Que 1. What is the effect of DNA copying which is not perfectly accurate in the reproduction process?

Ans. The DNA copying which is not perfectly accurate in the reproduction process results in variation in populations for better survival of the species.

Que 2. What methods will you use for growing jasmine and rose plants?

Ans. For growing jasmine plants, layering method will be used and for growing rose plants, cutting and grafting methods will be used.

Que 3. Name the part of Bryophyllum where the buds are produced for vegetative propagation.

Ans. In Bryophyllum, the buds are produced in leaf notches.

Que 4. Which parts of plants can grow vegetatively?

Ans. Modified stems like onion bulbs, runners of doob grass, ginger rhizomes, potato tubers, root tubers of sweet potato and dahlia, stem cutting of plants like rose and leaves of plants like Bryophyllum can be grown vegetatively.

Que 5. can you consider cell division as a type of reproduction in unicellular organism? Give one reason.

Ans. Yes, because it results in the formation of two daughter cells, i.e. It results in the production of more individuals of the organism

Que 6. What is the function of pollen grains in flowers?

Ans. Pollen grains are the male gametes which fertilise the egg cell present in the ovule.

Que 7. Write the various methods of cross-pollination.

Ans. Various methods of cross-pollination are entomophily (insect pollination), anemophily (wind pollination), hydrophily (water pollination) and zoophily (animal pollination).

Que 8. Why cannot fertilisation take place in flowers if pollination does not occur?
                                                     Or
Why is fertilisation not possible without pollination?

Ans. In a flower, fertilisation requires both male and female gametes. If pollination does not occur, male gametes will not be available hence fertilisation cannot take place.

Que 9. Explain the role of cotyledon and plumule in germination.

Ans. Cotyledon stores food and the plumule acts as future shoot.

Que 10. Is the chromosome number of zygote, embryonal cells and adult of a particular organism always constant? How is the constancy maintained in these three stages?

Ans. Yes, the constancy is maintained because cells in all these three structures undergo only mitotic divisions.

Que 11. In a bisexual flower inspite of the young stamens being removed artificially, the flower produces fruit. How is it possible?

Ans. This is because the pistil is intact due to which cross-pollination takes place leading to fertilisation and formation of fruit.

Que 12. Can you consider cell division as a type of reproduction in unicellular organism? Give one reason.

Ans. Yes, because it results in the formation of two daughter cells, i.e., it results in the production of more individuals of the organism.

Que 13. What is gametogenesis?

Ans. Formation of sperms in testes and ova in ovary is called gametogenesis.

Que 14. In tobacco plant, the male gametes have twenty four chromosomes. What is the number of chromosomes in the female gamete? What is the number of chromosomes in the zygote?

Ans. Number of chromosomes in female gamete is 24 and in zygote it is 48.

Que 15. How is the sperm genetically different from the egg?

Ans. Sperms contain either X or Y chromosome whereas an egg will always have an X chromosome.

Que 16. What would be the ratio of chromosome number between an egg and its zygote? How is the sperm genetically different from the egg?

Ans. The ratio is 1: 2 Sperms contain either X or Y chromosome whereas an egg will always have an X chromosome.

Que 17. List two functions performed by the testis in human beings.

Ans. Functions of testis: 

(i) To produce sperms. 

(ii) To produce male sex hormone/testosterone.

Que 18. List two functions of ovary of human female reproductive system.

Ans. (i) To produce female gamete. 

(ii) To secrete female hormones.

Que 19. Name the life process of an organism that helps in the growth of its population.

Ans. Reproduction helps in the growth of the population.

Que 20. What happens when a mature Spirogyra filament attains considerable length?

Ans. When a mature Spirogyra filament attains considerable length its filament breaks up into smaller fragments and each fragment grows into a new filament or individual.

Que 21. Name two simple organisms having the ability of regeneration.

Ans. Planaria/Hydra/Earthworm. (Any two)

Que 22. What happens when a Planaria gets cut into two pieces?

Ans. Each piece regenerates into a new Planaria.

Que 23. Name the method by which Hydra reproduces. Is this method sexual or asexual?

Ans. Hydra reproduces by budding or regeneration. 

It is a method of asexual reproduction.

Que 24. Name the male and female gametes in animals.

Ans. Male gametes are called sperms while female gametes are called eggs or ova.

Que 25. Why are testes placed outside the abdominal cavity in the scrotal sac?

Ans. Testes are placed outside the body cavity in the scrotal sac because it requires a temperature 2°C lower than the normal body temperature for production of sperms.

Que 26. What is hymen?

Ans. It is a thin fold of mucous membrane which partly closes the external vaginal opening in the unmarried girls.

Que 27. What is funeral of unfertilised egg?

Ans. Menstruation is also called funeral of egg since it is not fertilised.

Que 28. What is gestation?

Ans. The period of development of foetus in the uterus till birth is called gestation. It is of 9 months duration (i.e., 280 days or 40 weeks from the first day of the last menstrual cycle) in human beings.

Que 29. Define parturition.

Ans. The birth of the fully developed foetus (childbirth) is called parturition

Que 30. Name the causative agent of the disease "Kala-azar" and its mode of asexual reproduction.

Ans. The causative agent is Leishmania and the mode of asexual reproduction is binary fission.

Que 31. Name the parts of a bisexual flower that are not directly involved in reproduction.

Ans. (i) Sepals/calyx  

(ii) Petals/Corolla 

(iii) Thalamus

Que 32. List two unisexual flowers. 

Ans. Water melon and papaya are unisexual flowers. 

Que 33. What is DNA? 

Ans. DNA is the carrier of hereditary information from parents to the next generation. 

Que 34. Write names of one male and one female sex hormone. 

Ans. Male sex hormone is testosterone and female sex hormone is oestrogen. 

Que 35. Write whether true (T) or false (F) : 

(i) Duration of menstrual cycle in human female is 20 days. 

(ii) Onset of menstruation is termed menopause 

(iii) In human beings, male attains puberty little later than females.

Ans. (i) F, (ii) F, (iii) T 

Que 36. What is syngamy? 

Ans. One male nucleus fuses with one female gamete or egg. This process of fusion of male and female nuclei is called syngamy. 

Que 37. What are those organisms called which bear both the sex organs in the same individual. Give one example of such organism.

Ans. Organisms bearing both the sex organs in the same individual are called bisexual. Example, Hydra, Mustard.

Que 38. Give an example of a unisexual and bisexual flower. 

Ans. Cucumber is a unisexual flower and hibiscus is a bisexual flower. 

Que 39. Where is the zygote located in the flower after fertilisation? 

Ans. Zygote is located inside the ovule which is present in the ovary.

Que 40. Where do the following functions occur? 

(i) Production of an egg       

(ii) Fertilisation 

(iii) Implantation of zygote.

Ans. (i) In ovary  

(ii) In fallopian tube  

(iii) In uterus (uterine wall).

Que 41. Give reason for the statement- Since the ovary releases one egg every month, the uterus also prepares itself every month by making its lining thick and spongy.

Ans. The lining of uterus becomes thick for nourishing the embryo if fertilisation takes place and egg reaches the uterus.

Que 42. What is menopause? 

Ans. The period of permanent cessation of menstruation in females, usually occurring between the age of 45 and 50.