--- title: "NCERT Solutions for Class 10 Science Chapter 7 Exercise Exercises" url: https://www.swavid.com/science/class/10/chapter/how-do-organisms-reproduce/ncert-solutions/exercise-exercises dateModified: 2026-10-07T16:44:39+00:00 --- # NCERT Solutions for Class 10 Science Chapter 7 Exercise Exercises Chapter 7: How do Organisms Reproduce?. Every question from Exercise Exercises, with full working and the final answer. Free PDF (10 pages): https://www.swavid.com/api/seo/pdf/ncert/science/class-10/swavid-ncert-solutions-class-10-science-chapter-7-how-do-organisms-reproduce-b9c3994334.pdf ## EXERCISES ### Question 1 *1 mark · MCQ* Asexual reproduction takes place through budding in - Amoeba. - Yeast. - Plasmodium. - Leishmania. **Solution** 1. Yeast is a unicellular fungus that reproduces asexually through budding. 2. Amoeba reproduces by binary fission, Plasmodium by multiple fission, and Leishmania by binary fission in a definite orientation. **Answer:** (b) Yeast. > Common mistake: Confusing budding in yeast with binary fission in amoeba or leishmania. ### Question 2 *1 mark · MCQ* Which of the following is not a part of the female reproductive system in human beings? - Ovary - Uterus - Vas deferens - Fallopian tube **Solution** 1. Vas deferens is a part of the male reproductive system that delivers sperms. 2. Ovary, uterus, and fallopian tube are parts of the female reproductive system. **Answer:** (c) Vas deferens > Common mistake: Choosing ovary or fallopian tube which are clearly female reproductive organs. ### Question 3 *1 mark · MCQ* The anther contains - sepals. - ovules. - pistil. - pollen grains. **Solution** 1. The anther is the part of the stamen that produces pollen grains. 2. Sepals and pistil are other floral parts, while ovules are contained inside the ovary. **Answer:** (d) pollen grains. > Common mistake: Confusing anther contents with ovules which are located inside the ovary of the pistil. ### Question 4 *3 marks · Short answer* What are the advantages of sexual reproduction over asexual reproduction? **Solution** 1. Sexual reproduction involves the combining of DNA from two different individuals, which creates new combinations of variants. 2. It generates greater variations compared to asexual reproduction, which are essential for the survival of species over time when niches change. 3. It provides long-term stability to populations by ensuring that some individuals have variations to adapt to altered environments. **Answer:** Sexual reproduction generates greater variations by combining DNA from two individuals, ensuring species survival and adaptability. > Common mistake: Writing that sexual reproduction makes the individual stronger instead of focusing on variation and population survival. ### Question 5 *3 marks · Short answer* What are the functions performed by the testis in human beings? **Solution** 1. The primary function of the testis is the formation or production of male germ-cells called sperms. 2. Testis is located outside the abdominal cavity in the scrotum to provide a lower temperature required for sperm formation. 3. It secretes the male hormone testosterone, which regulates sperm formation and brings about secondary sexual changes in boys at puberty. **Answer:** The testes produce sperms and secrete the hormone testosterone. > Common mistake: Forgetting to mention the hormone secretion or the role of the scrotum. ### Question 6 *3 marks · Short answer* Why does menstruation occur? **Solution** 1. The ovary releases one egg every month, and the uterus prepares itself every month to receive a fertilised egg by making its lining thick and spongy. 2. If fertilisation does not take place, the egg lives for about one day and the thickened uterine lining is no longer needed. 3. This lining slowly breaks and comes out through the vagina as blood and mucous, a cycle known as menstruation. **Answer:** Menstruation occurs when the unfertilised egg and the thickened uterine lining are shed out of the body. > Common mistake: Stating that menstruation happens because the egg is fertilized instead of unfertilized. ### Question 7 *5 marks · Long answer* Draw a labelled diagram of the longitudinal section of a flower. **Solution** 1. Diagram: Draw a clean, labelled diagram of the longitudinal section of a flower showing the female and male reproductive parts as given in Fig. 7.7 of the textbook. 2. Label the parts clearly: Stigma, Style, Ovary, Anther, Filament, Petal, and Sepal. 3. The outermost whorl consists of green sepals that protect the flower in the bud stage. 4. The petals are brightly coloured to attract insects for pollination. 5. The staman (anther and filament) is the male reproductive part producing pollen grains, and the pistil (stigma, style, ovary) is the female reproductive part containing ovules. **Answer:** A correctly drawn and labelled longitudinal section of a flower showing sepals, petals, stamen, and pistil. > Common mistake: Incorrectly labelling the anther and filament or missing the ovary and ovule structures. ### Question 8 *3 marks · Short answer* What are the different methods of contraception? **Solution** 1. Mechanical barriers: Devices like condoms on the penis or coverings in the vagina prevent sperm from reaching the egg. 2. Chemical and hormonal methods: Oral pills change the hormonal balance of the body so that eggs are not released, and devices like copper-T or loop are placed in the uterus. 3. Surgical methods: Blocks are created surgically, such as blocking the vas deferens in males or the fallopian tubes in females, to prevent gamete transfer. **Answer:** The different methods of contraception include mechanical barriers, chemical and hormonal methods, intrauterine devices, and surgical methods. > Common mistake: Forgetting to mention surgical methods or confusing barrier methods with hormonal pills. ### Question 9 *3 marks · Short answer* How are the modes for reproduction different in unicellular and multicellular organisms? **Solution** 1. In unicellular organisms, reproduction occurs by simple cell division, fission, budding, or fragmentation, where the entire body participates in creating new individuals. 2. In simple multicellular organisms like Spirogyra, simple reproductive methods such as fragmentation can occur, where the body simply breaks up into smaller pieces upon maturation. 3. In complex multicellular organisms, cell-by-cell division is impractical because specialized cells are organized as tissues and organs at definite positions; hence, they use complex methods like sexual reproduction and specialized reproductive organs. **Answer:** Unicellular organisms reproduce through simple cell division or fission, whereas multicellular organisms use specialized cells, tissues, or sexual modes of reproduction due to their complex body organization. > Common mistake: Stating that all multicellular organisms reproduce sexually without mentioning simple multicellular forms like Spirogyra or Hydra. ### Question 10 *3 marks · Short answer* How does reproduction help in providing stability to populations of species? **Solution** 1. Populations of organisms fill well-defined places, or niches, in the ecosystem using their ability to reproduce. 2. The consistency of DNA copying during reproduction is important for the maintenance of body design features that allow the organism to use that particular niche, ensuring population stability. 3. Variations introduced during reproduction allow some individuals to survive even when ecological niches undergo drastic changes, ensuring the survival of the species over time. **Answer:** Reproduction maintains the consistency of body designs suited to specific niches, and the built-in variations ensure the survival and stability of populations against environmental changes. > Common mistake: Explaining individual survival instead of focusing on population stability and species survival in a niche. ### Question 11 *3 marks · Short answer* What could be the reasons for adopting contraceptive methods? **Solution** 1. To prevent unwanted pregnancies and maintain a desired family size, avoiding the major physical and mental demands of frequent pregnancies on women. 2. To regulate birth rates and control population growth, which helps in improving standard of living and health. 3. To prevent the transmission of sexually transmitted diseases (STDs) such as HIV-AIDS, gonorrhoea, and syphilis by using barrier methods like condoms. **Answer:** Contraceptive methods are adopted to prevent unwanted pregnancies, control population growth, and protect against sexually transmitted diseases. > Common mistake: Mentioning only pregnancy prevention and omitting the prevention of sexually transmitted diseases. ## Related pages - [All Chapter 7 NCERT solutions](https://www.swavid.com/science/class/10/chapter/how-do-organisms-reproduce/ncert-solutions) Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student