Chapter 8 . How do Organisms Reproduce ?

Class 10 Science Chapter 8 . How do Organisms Reproduce ? Internal Questions and Answers :

Internal Question :

1. What is the importance of DNA copying in reproduction?

Answer:  DNA copying, or DNA replication, is essential in reproduction as it ensures that the genetic information is accurately passed on to the offspring. It allows for the faithful transmission of genetic instructions, enabling the inheritance of traits and maintaining genetic continuity across generations.
2. Why is variation beneficial to the species but not necessarily for the individual?

Answer:  Variation is beneficial to the species because it increases the likelihood of some individuals possessing advantageous traits that can better adapt to changing environments, leading to improved survival and reproductive success. However, for an individual, excessive variation may increase the risk of being less adapted and less competitive in their specific environment.

Internal Question :

1. How does binary fission differ from multiple fission?

Answer:  Binary fission is a form of asexual reproduction in which a single parent cell divides into two identical daughter cells. Multiple fission, on the other hand, is a form of asexual reproduction where a parent cell divides into multiple daughter cells simultaneously, resulting in the formation of several offspring.
2. How will an organism be benefited if it reproduces through spores?

Answer: Reproduction through spores offers several benefits to organisms. Spores are lightweight and can be easily dispersed by wind or other means, allowing for colonization of new habitats. They are also resistant to adverse conditions, ensuring survival during unfavorable periods and facilitating the spread of the species.
3. Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?

Answer: More complex organisms have specialized cells and tissues that are highly differentiated and often have limited regenerative abilities. Their complex anatomical structures and functional requirements make complete regeneration of new individuals impractical or impossible.
4. Why is vegetative propagation practised for growing some types of plants?

Answer: Vegetative propagation is practiced for growing certain types of plants because it allows for the production of genetically identical offspring. This method ensures that desirable traits and characteristics are preserved in the new plants, such as disease resistance or specific flower color, without relying on seed production or genetic recombination through sexual reproduction.
5. Why is DNA copying an essential part of the process of reproduction?

Answer: DNA copying, or DNA replication, is essential in the process of reproduction because it ensures that each new offspring receives an accurate and complete copy of the genetic information from the parent. This fidelity in DNA copying is crucial for maintaining genetic continuity and passing on inherited traits to subsequent generations.

Internal Question :

1. How is the process of pollination different from fertilisation?

Answer: Pollination is the transfer of pollen from the male reproductive organ (anther) to the female reproductive organ (stigma) of a flower. Fertilization, on the other hand, occurs when the sperm from the pollen combines with the egg in the ovule, leading to the formation of a zygote and the development of seeds.
2. What is the role of the seminal vesicles and the prostate gland?

Answer: The seminal vesicles and the prostate gland are both accessory reproductive glands in males. The seminal vesicles produce a fluid rich in fructose, enzymes, and prostaglandins, which nourish and activate sperm. The prostate gland secretes a milky fluid that helps to protect and enhance the motility of sperm.
3. What are the changes seen in girls at the time of puberty?

Answer: During puberty, girls undergo several physical and physiological changes are :

(i) Development of breasts

(ii) Growth of pubic hair and underarm hair

(iii) Onset of menstruation (menarche)

(iv) Growth spurt and increase in height

(v)  Development of hips and widening of the pelvis

(vi) Maturation of reproductive organs and the ability to conceive.

4. How does the embryo get nourishment inside the mother’s body?

Answer: The embryo receives nourishment inside the mother's body through the placenta. The placenta is a specialized organ that forms during pregnancy. It is connected to the embryo through the umbilical cord and facilitates the exchange of oxygen, nutrients, and waste products between the mother's bloodstream and the developing embryo.
5. If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?

Answer: No, a copper-T intrauterine device (IUD) does not provide protection against sexually transmitted diseases (STDs). Copper-T is a form of long-acting reversible contraception that primarily works by preventing pregnancy. To prevent the transmission of STDs, it is important to use barrier methods such as condoms in addition to contraception methods like the copper-T.

Class 10 Science Chapter 8 . How do Organisms Reproduce ?  Exercises :

1. Asexual reproduction takes place through budding in
(a) amoeba.
(b) yeast.
(c) plasmodium.
(d) leishmania.

Answer : (b) yeast.

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
3. The anther contains
(a) sepals.
(b) ovules.
(c) carpel.
(d) pollen grains.

Answer : (d) pollen grains.
4. What are the advantages of sexual reproduction over asexual reproduction?

Answer: Advantages of sexual reproduction over asexual reproduction include increased genetic diversity, allowing for adaptation to changing environments, repair of DNA damage through recombination, elimination of harmful traits, evolutionary innovation, co-evolution with other species, and the potential for offspring to inherit beneficial combinations of genes.
5. What are the functions performed by the testis in human beings?

Answer: The testes in human beings have several functions:

(i) Production of sperm cells through spermatogenesis.

(ii) Secretion of testosterone, the primary male sex hormone, which is responsible for the development of male secondary sexual characteristics, maintenance of reproductive tissues, and regulation of reproductive functions.

6. Why does menstruation occur?

Answer: Menstruation occurs as a result of the shedding of the uterine lining (endometrium) when pregnancy does not occur. It is part of the menstrual cycle and prepares the uterus for potential implantation of a fertilized egg.
7. Draw a labelled diagram of the longitudinal section of a flower.

Answer:  The longitudinal section of a flower :

8. What are the different methods of contraception?

Answer: There are different methods of contraception :

Barrier methods: Condoms, diaphragms, and cervical caps that physically block sperm from reaching the egg.

Hormonal methods: Birth control pills, patches, injections, and hormonal intrauterine devices (IUDs) that use hormones to prevent ovulation or thicken cervical mucus.

Intrauterine devices (IUDs): T-shaped devices inserted into the uterus to prevent fertilization and implantation.

Sterilization: Permanent methods like tubal ligation (female sterilization) or vasectomy (male sterilization) that prevent pregnancy by blocking or cutting the fallopian tubes or vas deferens.

Emergency contraception: "Morning-after pills" taken after unprotected intercourse to prevent pregnancy.

Natural methods: Tracking fertility signs, such as basal body temperature or cervical mucus changes, to identify fertile days and avoid intercourse.

Behavioral methods: Withdrawing (pulling out) before ejaculation or practicing abstinence during fertile periods.

Permanent contraception: Surgical procedures like bilateral salpingectomy (removal of fallopian tubes) or hysterectomy (removal of the uterus) for permanent sterilization.

9. How are the modes for reproduction different in unicellular and multicellular organisms?

Answer: The modes of reproduction different between unicellular and multicellular organisms. Unicellular organisms, such as bacteria and protists, reproduce asexually through processes like binary fission or budding, resulting in identical offspring. Multicellular organisms, including plants and animals, reproduce sexually, involving the fusion of gametes from two parents to produce genetically diverse offspring with combinations of traits from both parents.

10. How does reproduction help in providing stability to populations of species?

Answer: Reproduction plays a crucial role in providing stability to populations of species. By producing offspring, individuals ensure the continuation of their genetic material and the survival of their species. Reproduction allows for genetic diversity, which increases the resilience of a population to environmental changes and reduces the risk of extinction. It also maintains a balance between birth and death rates, ensuring a stable population size that can adequately utilize available resources and maintain ecological equilibrium.
11. What could be the reasons for adopting contraceptive methods?

Answer: There are several reasons why individuals and couples may choose to adopt contraceptive methods:

Family planning: Contraception allows individuals to plan and space their pregnancies according to their desires and circumstances.

Preventing unintended pregnancies: Contraception helps avoid unintended pregnancies, which can have significant social, emotional, and financial consequences.

Health considerations: Contraception can be used to manage and prevent certain health conditions associated with pregnancy, such as high-risk pregnancies or medical conditions that may worsen during pregnancy.

Economic stability: Contraception enables individuals and families to make informed decisions about their reproductive choices, considering their financial resources and goals.