CBSE Class 10 Biology How Do Organisms Reproduce Worksheet Set E

VERY SHORT ANSWER TYPE QUESTIONS 

Question. Why is fertilisation not possible without pollination in plants?
Answer. Fertilisation is the process in which pollen grain and egg fuse to form zygote. Pollination is the process of transfer of pollen grains from stamen to the stigma of carpel. It means that fertilisation is not possible without pollination.

Question. What is the role of seminal vesicles and prostate gland? 
OR
Write the functions of secretions of prostate gland and seminal vesicles in humans. 
Answer. Seminal vesicle: It holds the liquid that mixes with sperm to form semen.
Prostate gland: It secretes fluid adding upto the semen and contains enzymes and other substances.
It also provides nutrition to the sperms, in the form of fructose and calcium. It protects sperms.

Question. What are sexually transmitted diseases? Name a STDs which damages the immune system of human body. 
Answer. Diseases that spread through the sexual contact are called STDs AIDS damages the body’s immune system.

Question. Trace the path of sperms from where they are produced in human body to the exterior. 
Answer. 
Testes → vas deferens → urethra → penis and then opens to outside.

Question. What is the main difference between sperms and eggs of humans? Write the importance of this difference. 
Answer. Sperms are motile (movable) and have X or Y chromosomes whereas eggs are non-motile and have X chromosome only.
The sperms can reach to egg for fertilisation because these are motile. Chromosomes in them help in determination of sex of a new born child.

Question. The chromosomal number of the sexually producing parents and their offspring is the same. Justify this statement.
Answer. (i) In sexual reproduction, fusion of male and female gametes takes place, each of their germ cells or gametes contain half the number of chromosomes.
(ii) When male and female gametes fuse at the time of fertilisation it restores the original number of chromosomes of parent.

Question. What happens when a Planaria gets cut into two pieces? 
Answer. Each piece regenerates into new organism, planaria.

Question. Differentiate between pollen grain and ovule. 
Answer. Pollen grains contain male gametes in plants and ovules contain female gametes.

Question. Differentiate between plumule and radicle.
Answer. 

Question. Why do we need to adopt contraceptive measures? 
Answer. (i) To prevent unwanted pregnancies.
(ii) To prevent STD (Sexually Transmitted Diseases).
(iii) To have proper gap between two children.
(iv) To control population.
(v) To have sound health.

Question. How is the process of pollination different from fertilisation? 
Answer. The process of transfer of pollens from anther to stigma is called pollination, which takes place only in plants.
Fertilisation is a process in which male sex cell and female sex cell join or fuse together to form zygote. It happens in all living organisms, in sexual reproduction.

Question. Give two differences between male gametes and female gametes. 
Answer. 

Question. List two preparations shown every month by the uterus in anticipation of pregnancy in the humans.
Answer. (i) The inner uterine wall becomes thick.
(ii) More blood vessels develop in its lining.

Question. Differentiate between the following:
(i) Role of placenta and uterus in pregnancy (ii) Unisexual and bisexual flowers
Answer. (i) Placenta: The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta.
Uterus: After fertilisation, embryo gets attached to the walls of uterus.
(ii) Unisexual flowers: Flowers which contain either stamens or carpels.
Bisexual flowers: Flowers which contain both stamens and carpels.

Question. If a women is using copper-T, will it help in protecting against sexually transmitted diseases?
Answer. No, it can only prevent unwanted pregnancy. It will not be able to prevent contact of body fluids.

Question. List two unisexual flowers. 
Answer. Watermelon, Cucumber and Willows (Any two)

Question. List two reasons for the appearance of variations among the progeny formed by sexual reproduction.
Answer. (i) Special cell division involved in the process of gametes formation is the cause of variations.
(ii) Genetic material comes from two parents, which brings variations in offsprings.

Question. List two functions performed by testis in human beings. 
Answer. 
(i) Testis produces sperms.
(ii) It produces testosterone hormone.

Question. What happens when a mature Spirogyra filament attains considerable length? 
Answer. A mature spirogyra filament breaks into smaller fragments and each fragment grows into a new plant.This process of reproduction is called fragmentation.

Question. Name the method by which hydra reproduces. Is this method sexual or asexual? 
Answer. Hydra reproduces by budding. It is an asexual mode of reproduction.

Question. Name the causative agent of the disease ‘kala-azar’ and its mode of asexual reproduction.
Answer. Leishmania causes ‘kala-azar’. It reproduces by binary fission in a definite orientation.

Question. What are those organisms called which bear both the sex organs in the same individual? Give one example of such organisms. 
Answer. These are called hermaphrodites, e.g. earthworm and leech.

Question. Select two plants from the following which are grown by vegetative propagation process:
Banana, Wheat, Mustard, Jasmine, Gram.
Answer. Banana and jasmine are grown by vegetative propagation, because they do not produce seeds.

Question. List two functions of ovary of human female reproductive system. 
Answer. 
(i) Ovary produces eggs for fertilisation.
(ii) They also produces hormones oestrogen and progestrone.

Question. Why is temperature of scrotal sac 2°C less than the body temperature? 
Answer. Scrotal sac temperature is less by 2° because sperms are safe at a little lower temperature than body temperature. It is outside the body that is why it has lower temperature than body.

Question. Give one difference between zygote and embryo.
Answer. Zygote is a single celled fusion product of sperm and ovum whereas embryo is a multicellular product produced by mitotic divisions from zygote.

Question. Write the expanded form of AIDS.
Answer. Acquired Immuno Deficiency Syndrome.

Question.Give an example of a flower which contains both stamens and carpels.
Answer. Hibiscus, Mustard (Any one)

Question. Give the respective scientific term used for studying.
(i) The mechanism by which variation are created and inherited and
(ii) The development of new type of organism from the existing ones. 
Answer. (i) Heredity, (ii) Evolution.

Question. Name the parts of a bisexual flower that are not directly involved in reproduction. 
Answer. Sepals and petals are not directly involved in reproduction.

Question.What happens when egg is not fertilised?
Answer. When egg is not fertilised, blood and mucus comes out through vagina. This process is called menstruation.

Question. Why does the lining of uterus becomes thick and spongy during every month?
Answer. The lining of uterus becomes thick and spongy by the action of progesterone to receive and nurture the development of embryo.

Question. Write the number of immature eggs present in the ovaries of newly born baby girl. Mention what happens to these immature eggs when the girl attains maturity. 
Answer. Ovaries contain thousands of immature eggs at the time of birth. Some of these eggs start maturing when girls attain puberty. One egg is produced every month by one of the ovaries.

Question. How can the chromosomes be identified? 
Answer. Chromosomes can be seen as thread like structure having specific shape when cell is dividing by which they can be identified.

Question. Differentiate between germination and fertilisation.
Answer. 
Germination: Involves development of embryo into a seedling.
Fertilisation: It involves fusion of male with female gametes.

Question. How does binary fission differ from multiple fission? 
Answer. In binary fission cell divides into two cells whereas in multiple fission a cell divide into many daughter cells.

Question. What is the role of scrotum? 
Answer. Scrotum regulates the temperature of testes and maintains it at 35°C, two degree below the body temperature, so as to protect sperms from high temperature.

Question. Name the part of Bryophyllum where the buds are produced for vegetative propagation. 
Answer.Buds arise from the notches in the leaf margins of Bryophyllum.

Question. State one function each performed by following organs in human beings.
(a) Testes (b) Prostate gland.
Answer. (a) Formation of sperms takes place in testes.
(b) Prostate gland contributes fluid to the semen.

Question. Name the method by which spirogyra reproduces under favourable conditions. Is this method sexual or asexual? 
Answer. Under favourable conditions, spirogyra reproduces by a process known as fragmentation. This is an asexual method of reproduction.

Question. How does Planaria reproduce? Is this method sexual or asexual?
Answer. Planaria reproduces by a process known as regeneration. It is a type of asexual reproduction in which if Planaria can be cut into any number of pieces, each piece grows into a new individual organism.