--- title: "NCERT Solutions Class 10 Science Ch 7 How do Organisms Reproduce?" url: https://www.swavid.com/science/class/10/chapter/how-do-organisms-reproduce/ncert-solutions dateModified: 2026-10-07T16:44:39+00:00 --- # NCERT Solutions Class 10 Science Ch 7 How do Organisms Reproduce? This chapter's questions cover the mechanisms, importance, and various modes of reproduction in single-celled organisms, plants, and human beings, along with reproductive health and contraception. 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 ## QUESTIONS ### Question 1 *3 marks · Short answer* What is the importance of DNA copying in reproduction? **Solution** 1. DNA copying is the basic event in reproduction that passes on genetic information from parents to the next generation. 2. It ensures that the offspring inherit body designs and characteristics similar to their parents. 3. It also creates variations during the copying process, which are essential for adaptation and evolution of the species. **Answer:** DNA copying transmits genetic blueprints to offspring, maintains body designs, and introduces variations necessary for evolution. > Common mistake: Students often forget to mention that DNA copying is responsible for passing body design blueprints and generating variations. ### Question 2 *3 marks · Short answer* Why is variation beneficial to the species but not necessarily for the individual? **Solution** 1. Variations are useful for the survival of species over time when environmental niches undergo drastic changes, such as rise in water temperature. 2. If a population has variations, some individuals may possess traits to survive such changes, preventing the whole species from getting wiped out. 3. However, for an individual organism, a particular variation might not be beneficial or could even be drastic, sometimes leading to the death of the newborn cell if it cannot work with the cellular apparatus. **Answer:** Variation ensures the survival of a species against drastic environmental changes, but for an individual, some variations can be harmful or fatal. > Common mistake: Students often write that variations are always beneficial to the individual organism, ignoring that drastic variations can be fatal. ## QUESTIONS ### Question 1 *3 marks · Short answer* How does binary fission differ from multiple fission? **Solution** 1. In binary fission, a single parent cell divides into two equal daughter cells, as seen in Amoeba. 2. In multiple fission, a single parent cell divides simultaneously into many daughter cells, as seen in Plasmodium. 3. Binary fission usually takes place under favourable conditions, whereas multiple fission often occurs during unfavourable conditions by forming a protective cyst. **Answer:** Binary fission produces two daughter cells, while multiple fission produces many daughter cells simultaneously from a single parent cell. > Common mistake: Confusing the organisms that undergo binary fission (Amoeba) with those that undergo multiple fission (Plasmodium). ### Question 2 *3 marks · Short answer* How will an organism be benefited if it reproduces through spores? **Solution** 1. Spores are covered by thick walls that protect them under unfavourable environmental conditions such as lack of moisture or extreme temperatures. 2. Due to their light weight and large numbers, spores can be easily dispersed by wind, water, or animals over long distances. 3. When spores come into contact with a moist surface, they germinate and grow into new individuals, helping the organism survive and spread. **Answer:** Spore formation protects organisms with thick walls during unfavourable conditions and aids in wide dispersal for survival. > Common mistake: Forgetting to mention the protective thick wall of spores. ### Question 3 *3 marks · Short answer* Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration? **Solution** 1. Complex multi-cellular organisms are not simply a random collection of cells. 2. Their specialised cells are organised into tissues, and tissues into organs that have to be placed at definite positions in the body. 3. Therefore, cell-by-cell division and complex organisation make simple regeneration impractical for giving rise to new individuals. **Answer:** Complex organisms have high specialisation with tissues and organs placed at definite positions, making simple regeneration impossible. > Common mistake: Stating that complex organisms cannot regenerate at all, instead of specifying that they cannot reproduce through regeneration. ### Question 4 *3 marks · Short answer* Why is vegetative propagation practised for growing some types of plants? **Solution** 1. Plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds. 2. It makes possible the propagation of plants such as banana, orange, rose, and jasmine that have lost the capacity to produce viable seeds. 3. All plants produced are genetically similar enough to the parent plant to retain all its desirable characteristics. **Answer:** Vegetative propagation allows earlier flowering and fruiting, propagation of seedless plants, and preservation of genetic traits. > Common mistake: Failing to mention seedless plants as a key application. ### Question 5 *3 marks · Short answer* Why is DNA copying an essential part of the process of reproduction? **Solution** 1. DNA in the cell nucleus is the information source for making proteins, which determine the body design of an organism. 2. DNA copying ensures that the offspring inherit the basic blueprint and characteristics from their parents. 3. Inbuilt variations during DNA copying provide the raw material for evolution and ensure the survival of species in changing environments. **Answer:** DNA copying transmits body design blueprints to the next generation and introduces variations essential for survival and evolution. > Common mistake: Writing that DNA copying creates exact copies without mentioning that minor variations always occur. ## QUESTIONS ### Question 1 *3 marks · Short answer* How is the process of pollination different from fertilisation? **Solution** 1. Pollination is the transfer of pollen grains from the anther to the stigma of a flower. 2. Fertilisation is the fusion of the male germ-cell with the female gamete present in the ovule. 3. Pollination occurs before fertilisation and helps bring the male and female gametes together. **Answer:** Pollination is the transfer of pollen from anther to stigma, whereas fertilisation is the fusion of male and female germ-cells. > Common mistake: Students often confuse pollination with fertilisation or state that both are the same process. ### Question 2 *3 marks · Short answer* What is the role of the seminal vesicles and the prostate gland? **Solution** 1. The secretions of the seminal vesicles and the prostate gland are added along the path of the vas deferens. 2. These secretions provide a fluid medium that makes the transport of sperms easier. 3. The fluid also provides nutrition to the sperms. **Answer:** Seminal vesicles and prostate gland add their secretions to provide nutrition and make the transport of sperms easier. > Common mistake: Forgetting to mention that these glands help in both transport and nutrition. ### Question 3 *3 marks · Short answer* What are the changes seen in girls at the time of puberty? **Solution** 1. Breast size begins to increase with the darkening of the skin of the nipples at the tips of the breasts. 2. Girls begin to menstruate at around this time. 3. Thick hair grows in new parts of the body such as armpits and the genital area, and skin frequently becomes oily leading to pimples. **Answer:** Puberty changes in girls include increase in breast size, initiation of menstruation, and growth of thick hair in new body parts. > Common mistake: Writing changes common to both boys and girls instead of specifically focusing on girls. ### Question 4 *3 marks · Short answer* How does the embryo get nourishment inside the mother's body? **Solution** 1. The embryo gets nutrition from the mother's blood with the help of a special disc-shaped tissue called placenta. 2. The placenta is embedded in the uterine wall and contains villi on the embryo's side with blood spaces surrounding them on the mother's side. 3. This provides a large surface area for glucose and oxygen to pass from the mother to the embryo. **Answer:** The embryo gets nourishment from the mother's blood through the placenta, which provides a large surface area for glucose and oxygen transfer. > Common mistake: Failing to mention the role and structure of the placenta. ### Question 5 *3 marks · Short answer* If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases? **Solution** 1. A copper-T is a contraceptive device placed in the uterus to prevent pregnancy. 2. It acts by preventing implantation or fertilisation. 3. It does not protect against sexually transmitted diseases (STDs) because it is not a barrier method like a condom. **Answer:** No, a copper-T will not help in protecting against sexually transmitted diseases as it only prevents pregnancy. > Common mistake: Assuming that all contraceptives protect against sexually transmitted diseases. ## 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. ## Frequently asked questions ### How many total questions are covered in the NCERT Solutions for Class 10 Science Chapter 7? This chapter covers a total of 23 questions across various sections, including 11 main exercise questions and 12 additional practice questions. SwaVid provides a free PDF and step-by-step solutions for all of them on this page only. ### Which important topics do the additional questions for this chapter cover? The additional questions cover core concepts such as the importance of DNA copying in reproduction, significance of variation, binary versus multiple fission, vegetative propagation, and contraception. You can find detailed answers to these topics in SwaVid's free PDF and step-by-step solutions on this page only. ### What are the hardest question types in this chapter and how should I approach them? Long answer questions related to human reproductive systems and flower fertilization are often considered the hardest because they require detailed explanations and diagrams. You should approach them by breaking down the process into sequential steps and using scientific terminology correctly. ### How can I write answers to get full marks in Class 10 board exams for this chapter? To get full marks, write your answers in clear points, highlight key biological terms, and draw neat, labeled diagrams where required. SwaVid's free PDF and step-by-step solutions on this page only demonstrate the exact answering style expected by examiners. ### Is the free PDF for these NCERT solutions available for download? Yes, you can easily access and download the complete study material for the 2026-27 session. SwaVid's free PDF and step-by-step solutions are available on this page only to help with your exam preparation. ## Related pages - [Exercise Exercises solutions](https://www.swavid.com/science/class/10/chapter/how-do-organisms-reproduce/ncert-solutions/exercise-exercises) - [How do Organisms Reproduce?: CBSE previous year questions](https://www.swavid.com/cbse/class-10/science/pyq/how-do-organisms-reproduce) - [Class 10 Science chapters](https://www.swavid.com/science/class/10) 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