HOW DO ORGANISMS REPRODUCE: Long Answer Type Question Class 10th Chapter 10 JKBOSE/NCERT
Long Answer Type Question
Question 1. State, in brief, the changes that take place in a fertilised egg (zygote) till the birth of the child in the human female reproductive system. What happens to the egg when it is not fertilised?
Answer: Changes in a fertilized egg (zygote) till birth in the human female reproductive system:
1. After fertilization, the zygote undergoes a series of divisions through a process called cleavage. It forms a ball of cells called a blastocyst.
2. The blastocyst implants itself into the uterine lining, a process known as implantation.
3. The blastocyst develops further, and the inner cell mass differentiates into three germ layers: ectoderm, mesoderm, and endoderm.
4. The ectoderm gives rise to the nervous system, skin, and hair.
5. The mesoderm develops into muscles, bones, circulatory system, and reproductive organs.
6. The endoderm forms the digestive system, lungs, and other internal organs.
7. The embryo grows and develops organs, limbs, and other structures. It receives oxygen and nutrients from the mother through the placenta.
8. During the later stages of development, the embryo is referred to as a fetus.
At the end of approximately nine months, the fetus is ready for birth, and the process of labour and delivery takes place.
When the egg is not fertilized, it passes through the fallopian tube and into the uterus. It does not implant into the uterine lining. In this case, the uterine lining sheds during the menstrual period, and the unfertilized egg is expelled from the body along with the menstrual blood.
Question 2. Explain the male reproductive system.
Answer: The male reproductive system consists of the following structures:
1. Testes: The testes are the primary male reproductive organs responsible for producing sperm and testosterone.
2. Epididymis: The epididymis is a coiled tube located on the surface of each testis. It is responsible for storing and maturing sperm.
3. Vas Deferens: The vas deferens is a muscular tube that carries sperm from the epididymis to the urethra.
4. Seminal Vesicles, Prostate Gland, and Bulbourethral Glands: These glands secrete fluids that combine with sperm to form semen.
5. Urethra: The urethra is a tube that serves both the reproductive and urinary systems. It carries urine from the bladder and semen from the reproductive organs.
6. Penis: The penis is the external male reproductive organ. It delivers sperm into the female reproductive tract during sexual intercourse.
Question 3. What is AIDS? What is the full form of 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.
Answer: AIDS stands for Acquired Immunodeficiency Syndrome. It is a chronic and life-threatening condition caused by the Human Immunodeficiency Virus (HIV). HIV primarily attacks the immune system, specifically CD4 cells (T cells), weakening the body’s ability to fight off infections and diseases.
One mode of transmission of AIDS is through unprotected sexual intercourse with an infected individual. The virus can be transmitted through the exchange of certain bodily fluids, including blood, semen, vaginal fluids, and breast milk.
One measure for the prevention of AIDS is practising safe sex, which involves using barrier methods of contraception such as condoms. Condoms create a physical barrier, preventing the exchange of bodily fluids and reducing the risk of HIV transmission. Additionally, regular testing for HIV, avoiding sharing needles, and educating individuals about the disease and its prevention are crucial in combating the spread of AIDS.
Question 4. Where is the embryo sac found? How many cells are present in an embryo sac?
Answer: The embryo sac is found within the ovule of a flower, specifically within the ovary. It is the female gametophyte, which develops from the megaspore. The embryo sac is a specialized structure that contains the egg cell (ovum) and other cells necessary for fertilization and the development of the embryo. It is typically located within the ovule’s embryo sac chamber.
The embryo sac consists of seven cells. These cells are organized into three distinct regions: the egg apparatus, the central cell, and the antipodal cells. The egg apparatus contains the egg cell and two synergids, which are involved in the fertilization process. The central cell contains two polar nuclei, which will fuse with a sperm cell during double fertilization to form the endosperm, a nutritive tissue in the seed.
Question 5. What is asexual reproduction? Write any four modes of asexual reproduction in lower organisms.
Answer: Asexual reproduction is a mode of reproduction that involves the production of offspring without the involvement of gametes or the union of reproductive cells. It results in the production of genetically identical or nearly identical offspring, also known as clones. Some modes of asexual reproduction in lower organisms include:
Binary fission: The organism divides into two equal-sized daughter cells.
Budding: A small outgrowth (bud) forms on the parent organism and eventually detaches to become a new individual.
Fragmentation: The parent organism breaks into fragments, and each fragment can develop into a new individual.
Example: Flatworms (Planaria).
Spore Formation: Specialized cells called spores are produced, which can develop into new individuals.
Example: Fungi (Molds and Yeasts).
Question 6. What is vegetative reproduction? Explain in brief various modes of vegetative propagation in plants.
Answer: Vegetative reproduction is a type of asexual reproduction in plants that involves the production of new individuals from vegetative parts such as stems, roots, or leaves, without the involvement of seeds or spores. Various modes of vegetative propagation include:
1. Runners or stolons: Above-ground stems that grow horizontally and produce new plantlets at their nodes. Example: Strawberry plants.
2. Rhizomes: Underground stems that grow horizontally and give rise to new shoots and roots. Example: Ginger.
3. Bulbs: Underground storage structures composed of modified leaves that produce new shoots. Example: Onion.
4. Tubers: Enlarged underground stems that store nutrients and produce new shoots. Example: Potato.
These methods of vegetative propagation allow plants to produce genetically identical offspring and are commonly used in horticulture and agriculture for plant propagation and reproduction.