NCERT Solutions for Class 10 Science Chapter 8 How do Organisms Reproduce
The Class 10 NCERT Solutions for Science Chapter 8 How do Organisms Reproduce includes all the intext and exercise questions. Class 10 Science Chapter 8 How do Organisms Reproduce NCERT questions and answers help students to clear their doubts and to obtain good marks in Class 10 board exam. All the solutions provided in this article are strictly based on the CBSE syllabus and curriculum.
Class 10 Science Chapter 8 NCERT Questions and Answers
Class 10 Science Chapter 8 How do Organisms Reproduce NCERT Questions and Answers are prepared by experts with a detailed explanation that will help students complete their assignments & homework. Having a good grasp over CBSE NCERT Solutions for Class 10 Science will further help the students in their preparation for board exams and other competitive exams such as NTSE, Olympiad, etc.
NCERT Solutions for Class 10 Science Chapter 8 Intext Questions
Intext Question (Page No. 128)
Question 1: What is the importance of DNA copying in reproduction?
Answer: DNA (Deoxyribonucleic acid) is the genetic material found in the chromosomes, which are present in the nucleus of a cell. The DNA is the information site for making proteins and each specific type of protein leads to a specific type of body design. Thus, it is the DNA molecule that determines the body design of an individual. Therefore, it can be concluded that it is the DNA that gets transferred from parents to off-springs and makes them look similar.
Question 2: Why is variation beneficial to the species but not necessarily for the individual?
Answer: The reason why the variation is beneficial to the species than individuals is because sometimes the climatic changes have a drastic effect on the species, which makes their survival difficult. For examples, if the temperature of the water body increases, then there might be certain species of microorganisms which might die. This may result in disturbance in the environment. So, variation is beneficial to species and not for the individuals.
Intext Question (Page No. 133)
Question 1: How does binary fission differ from multiple fission?
Answer:
| Binary fission | Multiple fission |
| In this an organism divides into two similar organisms. | In this an organism produces two or more organisms. |
| A cyst or thick layer is not formed around the cell. | A cyst or thick layer is formed around the cell. |
| It generally occurs in favourable conditions Example: Amoeba, paramecium | It can take place in unfavourable conditions too. Example: Malarial parasite. |
Question 2: How will an organism be benefited if it reproduces through spores?
Answer: There are many advantages, if an organism reproduces through spores.
Advantages of spore formation:
- Large numbers of spores are produced in one sporangium.
- Spores are distributed easily by air to far-off places to avoid competition at one place.
- Spores are covered by thick walls to prevent dehydration under unfavourable conditions.
Question 3: Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Answer 3: Simple organisms such as Hydra and Planaria are capable of producing new individuals through the process of regeneration. The process of regeneration involves the formation of new organisms from its body parts. Simple organisms can utilize this method of reproduction as their entire body is made of similar kind of cells in which any part of their body can be formed by growth and development.
However, complex organisms have organ-system level of organization. All the organ systems of their body work together as an interconnected unit. They can regenerate their lost body parts such as skin, muscles, blood, etc. However, they cannot give rise to new individuals through regeneration.
Question 4: Why is vegetative propagation practised for growing some types of plants?
Answer: Following are the advantages of practising vegetative propagation for growing some types of plants:
- Crops like orange, banana, pineapple do not have viable seeds, so vegetative propagation can be used.
- It is a rapid, cheap and easier method to grow crops.
- It can be used in places where seed germination fails.
- A good quality of variety can be preserved.
Question 5: Why is DNA copying an essential part of the process of reproduction?
Answer: DNA (Deoxyribonucleic acid) copying is an essential part of reproduction as it passes genetic information from parents to offspring. It determines the body design of an individual. The reproducing cells produce a copy of their DNA through some chemical reactions and result in two copies of DNA. The copying of DNA always takes place along with the creation of additional cellular structure. This process is then followed by division of a cell to form two cells.
Intext Question (Page No. 140)
Question 1: How is the process of pollination different from fertilization?
Answer: Pollination is defined as the process of transfer of pollens from anther to stigma. The process takes place with the help of pollinators like air, water and some insects.
Fertilization is defined as the fusion of male and female gametes. It takes place in the ovule and leads to the formation of zygote.
Question 2: What is the role of the seminal vesicles and the prostate gland?
Answer: The secretions from seminal vesicles and prostate glands lubricate the sperms and provide a fluid medium for easy transport of sperms. Their secretion also provides nutrient in the form of fructose, calcium, and some enzymes.
Question 3: What are the changes seen in girls at the time of puberty?
Answer: Secondary sexual characteristics in girls:
- Increase in breast size and darkening of skin of the nipples present at the tips of the breasts.
- Appearance of hair in the genital area.
- Appearance of hair in other areas of skin like underarms, face, hands, and legs.
- Increase in the size of uterus and ovary.
- Beginning of menstrual cycle.
- More secretion of oil from the skin, which results in the appearance of pimples.
Question 4: How does the embryo get nourishment inside the mother’s body?
Answer: The embryo develops inside the mother’s body for about nine months. Inside the uterus, the outer tissue surrounding the embryo develops finger-like projections called villi. These villi are surrounded by uterine tissue and maternal blood. They provide a large surface area for exchange of oxygen and nutrients. Also, there is a special tissue called placenta, which is embedded in the uterine wall. The embryo receives the oxygen and nutrients from the mother’s blood via the placenta. The waste materials produced by the embryo are also removed through the placenta.
Question 5: If a woman is using a copper−T, will it help in protecting her from sexually transmitted diseases?
Answer: No, because usage of copper-T cannot stop the contact of body fluids. Hence, it cannot protect her from getting sexually transmitted diseases.
NCERT Solutions for Class 10 Science Chapter 8 Exercise Questions
Question 1: Asexual reproduction takes place through budding in
(a) amoeba
(b) yeast
(c) plasmodium
(d) leishmania
Answer: (b) in yeast.
Question 2: Which of the following is not a part of the female reproductive system in human beings?
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube
Answer: (c) Vas deferens
Question 3: The anther contains
(a) sepals
(b) ovules
(c) carpel
(d) pollen grains
Answer: (d) pollen grains.
Question 4: What are the advantages of sexual reproduction over asexual reproduction?
Answer: Advantages of sexual reproduction:
- In sexual reproduction, more variations are produced. Thus, it ensures survival of species in a population.
- The new formed individual has characteristics of both the parents.
- Variations are more viable in sexual mode than in asexual one. This is because in asexual reproduction, DNA has to function inside the inherited cellular apparatus.
Question 5: What are the functions performed by the testis in human beings?
Answer: The testes are the male reproductive organs that are located outside the abdominal cavity within a pouch called scrotum.
Functions of testes:
- Produce sperms
- Produce a hormone called testosterone, which brings about secondary sexual characters in boys.
Question 6: Why does menstruation occur?
Answer: Menstruation is a process in which blood and mucous flows out every month through the vagina. This process occurs every month because one egg is released from the ovary every month and at the same time, the uterus (womb) prepares itself to receive the fertilized egg. Thus, the inner lining of the uterus gets thickened and is supplied with blood to nourish the embryo. If the egg does not get fertilized, then the lining of the uterus breaks down slowly and gets released in the form of blood and mucous from the vagina.
Question 7: Draw a labelled diagram of the longitudinal section of a flower.
Answer:
Question 8: What are the different methods of contraception?
Answer: The contraceptive methods can be broadly divided into the following types:
Natural method: It involves avoiding the chances of meeting of sperms and ovum. In this method, the sexual act is avoided from day 10th to 17th of the menstrual cycle because during this period, ovulation is expected and therefore, the chances of fertilization are very high.
Barrier method: In this method, the fertilization of ovum and sperm is prevented with the help of barriers. Barriers are available for both males and females. Condoms are barriers made of thin rubber that are used to cover penis in males and vagina in females.
Oral contraceptives: In this method, tablets or drugs are taken orally. These contain small doses of hormones that prevent the release of eggs and thus fertilization cannot occur.
Implants and surgical methods: Contraceptive devices such as the loop or Copper-T are placed in uterus to prevent pregnancy. Some surgical methods can also be used to block the gamete transfer. It includes the blocking of vas deferens to prevent the transfer of sperms known as vasectomy. Similarly, fallopian tubes of the female can be blocked so that the egg will not reach the uterus known as tubectomy.
Question 9: How are the modes for reproduction different in unicellular and multicellular organisms?
Answer:
| Reproduction mode in unicellular organisms | Reproduction mode in multicellular organisms |
| (i) A sexual reproduction takes place in unicellular organisms. | (i) Sexual reproduction takes place in multicellular organisms. |
| (ii) Only one organism is required in this method. | (ii) A male and a female both are required in this method. |
| (iii) No special cells are present for reproduction. | (iii) Special cells are present for reproduction. |
| (iv) No special organs are present for reproduction. | (iv) Special organs are present for reproduction located at the fixed position in the body. |
Question 10: How does reproduction help in providing stability to populations of species?
Answer: Living organisms reproduce for the continuation of a particular species. It helps in providing stability to the population of species by producing a new individual that resembles the parents. This is the reason why cats give birth to only cats or dogs give birth to only dogs. Therefore, reproduction provides stability to populations of dogs or cats or any other species.
Question 11: What could be the reasons for adopting contraceptive methods?
Answer: Following are the reasons for adopting contraceptive methods:
- To control population
- To avoid unplanned pregnancy
- To avoid transfer of sexually transmitted diseases
Topics covered under Class 10 Science Chapter 8 How do Organisms Reproduce
Below we have listed the topics discussed in NCERT Solutions for Class 10 Science Chapter 8. The list gives you a quick look at the different topics and subtopics of this chapter.
| Section in NCERT Book | Topics Discussed |
|---|---|
| 8.1 | Do Organisms create exact copies of Themselves |
| 8.2 | Modes of Reproduction Used by Single Organisms |
| 8.3 | Sexual Reproduction |
| 8.3.1 | Why Sexual Mode of Reproduction? |
| 8.3.2 | Sexual Reproduction in Flowering Plants |
| 8.3.3 | Reproduction in Human Beings |
NCERT Solutions for Class 10 Science Chapter 8 – A Brief Discussion
Chapter Overview: Have you ever wondered why do organisms reproduce? Whatever the answer to this question but it is obvious that we see organisms because they reproduce. In this chapter, you will learn about the modes of reproduction used by unicellular such as fission, fragmentation, regeneration, budding, vegetative propagation and spore formation. All these modes are the asexual modes of of reproduction. Mutlicellular organisms prefer sexual mode of reproduction over asexual mode. This chapter explains you the sexual mode of reproduction in plants and animals.