Class 10 Science Chapter 7 Case Based Questions - How Do Organisms Reproduce

Case Study - 1

The sexual act always has the potential to lead to pregnancy. Pregnancy will make major demands on the body and the mind of the woman, and if she is not ready for it, her health will be adversely affected. Therefore, many ways have been devised to avoid pregnancy.

Q1: What are the different methods to prevent pregnancy?
Ans: Uses of contraceptive such as condoms, pills, copper -T and surgical methods.

Q2: What are the surgical methods to prevent pregnancy?
Ans: Tubectomy in females and vasecotomy in males.

Q3: Why the female sex ratio is declining day by day?
Ans: Due to female foeticides by doing illegal sex selective abortion of female foetuses.

Q4: Which contraceptive methods have large side effects?
Ans: Oral pills and by changing the hormonal balance leads to high side effect.

Q5: Why should one have the knowledge about sexual act and the disease causing by it?
Ans: To stay healthy and free free from sexually transmitted disease one should be aware of the disease cause by bacteria and viruses such as gonorrhoea, syphilis and HIV- AIDS.

Case Study - 2

Chromosomes in the nucleus of a cell contain information for inheritance of features from parents to next generation in the form of DNA (Deoxyribo Nucleic Acid) molecules. The DNA in the cell nucleus is the information source for making proteins. If the information is changed, different proteins will be made. Different proteins will eventually lead to altered body designs. Therefore, a basic event in reproduction is the creation of a DNA copy. Cells use chemical reactions to build copies of their DNA.

Q1: What is the importance of variation?
Ans: Variation is important for the survival of species over time. Variation make the species resistant to the changing environment and hence, it make easy for their survival.

Q2: Which mode of reproduction does not show much variation?
Ans: Generally, asexual reproduction show less variation which includes budding, fragmentation, fission etc.

Q3: What are the different modes of reproduction of single celled organism?
Ans: Fission, fragmentation, Budding  and regeneration.

Q4: What are the features of sexual reproduction?
Ans: It includes both the parents to produce offsprings and DNA copy is a crucial part of it.

Q5: Which mode of reproduction is better and why?
Ans: Sexual reproduction is better than asexual reproduction as the chances of survival of the species is higher in sexual reproduction.

Case Study - 3

There are many plants in which parts like the root, stem and leaves develop into new plants under appropriate conditions. Unlike in most animals, plants can indeed use such a mode for reproduction. This property of vegetative propagation is used in methods such as layering or grafting to grow many plants like sugarcane, roses, or grapes for agricultural purposes

Q1: What are the advantages of vegetative propagation?
Ans: All plants that are produced by such method are genetically similar to their parent and have all its characteristics. easy, less expensive and a fast method.

Q2: Give a example of vegetative propagation through buds?
Ans: Bryophyllum

Q3: What is tissue culture?
Ans: New plants are grown first in suitable artificial medium and then placing it in the soil to grow into mature plants.

Q4: What is grafting?
Ans: New plants are grown by joining a scion(upper portion of plant) to a stock of other plants in such a manner that they get united to each other.
Example: Roses

Q5: What are the examples of layering?
Ans: Jasmine or Grapevine.

Case Study - 4

The reproductive parts of angiosperms are located in the flower. You have already studied the different parts of a flower – sepals, petals, stamens and pistil. Stamens and pistil are the reproductive parts of a flower which contain the germ-cells.The flower may be unisexual (papaya, watermelon) when it contains either stamens or pistil or bisexual (Hibiscus, mustard) when it contains both stamens and pistil.

Q1: What is the male reproductive parts of flower?
Ans: Stamen is the male reproductive part of flower and it consist of anther and filament.

Q2: What are the different part of pistil?
Ans: Stigma, style and ovary.

Q3: What is pollination?
Ans: The transfer of pollen grains from the stamen to the stigma of flower is called pollination.

Q4: Where does fertilization occur in flower?
Ans: The fertilization takes place inside the ovule.

Q5: What are the two types of pollination?
Ans: Self pollination and cross pollination.

Case Study - 5

When a girl is born, the ovaries already contain thousands of immature eggs. On reaching puberty, some of these start maturing. One egg is produced every month by one of the ovaries. The egg is carried from the ovary to the womb through a thin oviduct or fallopian tube. The two oviducts unite into an elastic bag-like structure known as the uterus. The uterus opens into the vagina through the cervix.

Q1: What is fertilization?
Ans: The fusion of male gametes(sperms) and the female gametes(egg) to form zygote is called fertilization.

Q2: Where does fertilization occur?
Ans: Fertilization occur in the oviduct or Fallopian tube.

Q3: What is placenta?
Ans: It is an special tissue which provide nutrition from mother’s blood to developing embryo.

Q4: What are the different parts of female reproductive system?
Ans: Fallopian tube, ovary, uterus, vagina and cervix.

Q5: What happens when egg is not fertilized?
Ans: If the egg is not fertilized, the thick lining of uterus is not needed. So, it breaks slowly and comes out through vagina as blood and vagina, which is called as menstruation.