NCERT Solutions for Class 10 Biology Chapter 8 : How do Organisms Reproduce?

Q: Question 1. How does binary fission differ from multiple fission?

Answer. Binary fission converts a single cell into two equal cells. Amoeba and Bacteria Division by binary fission occurs in Amoeba and bacteria. Multiple fission is the simultaneous division of one cell into numerous daughter cells. Multiple fission occurs in Amoeba and Plasmodium.

Q: Question 2. Why is DNA copying an essential part of the process of reproduction?

Answer. The transmission of genetic information from parents to offspring requires the copying of DNA (deoxyribonucleic acid). An individual's body design is determined. The reproducing cells generate a copy of their DNA through chemical reactions, resulting in two copies of DNA. The copying of DNA occurs with the formation of new cellular structures. The division of a cell to produce two cells follows this pattern.

Q: Question 3. What is the role of the seminal vesicles and the prostate gland?

Answer. The secretions from the seminal vesicles and prostate glands lubricate the sperms and provide a fluid medium for sperm transmission. They also give the streaming sperm sustenance in the form of fructose, calcium, and enzymes so that they can survive for a few days before fertilising the egg.

Q: Question 4. Why is vegetative propagation used to grow some plant species?

Answer. Vegetative propagation is asexual reproduction carried out by plant vegetative parts (leaf, stem, and roots). This type of reproduction is self-sustaining and takes place without the use of seeds. It has numerous advantages, including: Plants having no viable seeds, such as orchids and bananas, are dispersed Plant propagation of a superior type since the plants produced will be genetically identical to the parent plant. A faster method of propagation for obtaining a big number of plants in a shorter amount of time. Plant introduction and propagation in newer locations where seeds may fail to germinate due to poor environmental or soil conditions.

Question 1

What is the important of DNA copying in reproduction?

Medium

Solution

Verified by Toppr

Answer

The replication of DNA ensures that both the daughter cells get identical copies of the genetic material. HenceDNA copying is important in reproduction. If cells divided without DNA replication, they could not pass on any genes from one cell generation to the next.

Answer

The replication of DNA ensures that both the daughter cells get identical copies of the genetic material. HenceDNA copying is important in reproduction. If cells divided without DNA replication, they could not pass on any genes from one cell generation to the next.

Question 2

Why is the variation beneficial to the species but no necessarily for the individual ?

Medium

Solution

Verified by Toppr

Answer

Variations and Natural selection is the basis of evolution. It is beneficial to the species to overcome changes and thrive under unfavorable conditions resulting in stable survival or elimination from the ecosystem.
The same change in an individual won't impact drastic change in the ecosystem. So, Variation is beneficial to the species but not necessarily for an individual.

Answer

Variations and Natural selection is the basis of evolution. It is beneficial to the species to overcome changes and thrive under unfavorable conditions resulting in stable survival or elimination from the ecosystem.
The same change in an individual won't impact drastic change in the ecosystem. So, Variation is beneficial to the species but not necessarily for an individual.

Question 3

The anther contains

A

Sepals

B

Ovules

C

Carpel

D

Pollen grains

Medium

Solution

Verified by Toppr

Answer

The stamen are male reproductive organs. They contain anther which is the site of pollen development. Inside anther male sporogenous cell differentiates and undergoes meiosis to produce microspores that develop into pollen grains.

Therefore, the correct answer is option D.

Answer

The stamen are male reproductive organs. They contain anther which is the site of pollen development. Inside anther male sporogenous cell differentiates and undergoes meiosis to produce microspores that develop into pollen grains.

Therefore, the correct answer is option D.

Question 4

What is the advantage of sexual reproduction over asexual reproduction?

Medium

Solution

Verified by Toppr

Answer

Sexual reproduction involves two parents, whereas asexual reproduction involves only one parent. So, the offspring resulting from sexual reproduction will have mixed characteristics from both the parents and therefore, will be different from each parent. This will bring variations in the population. Variations are important for the survival of species over time. If a population of asexually reproducing organisms is suited to a particular environmental condition and the condition is drastically altered then the population would be wiped out. However, if some variations were to be present in a few individuals in this population, there would be some chance for them to survive in the new environmental condition.

Answer

Sexual reproduction involves two parents, whereas asexual reproduction involves only one parent. So, the offspring resulting from sexual reproduction will have mixed characteristics from both the parents and therefore, will be different from each parent. This will bring variations in the population. Variations are important for the survival of species over time. If a population of asexually reproducing organisms is suited to a particular environmental condition and the condition is drastically altered then the population would be wiped out. However, if some variations were to be present in a few individuals in this population, there would be some chance for them to survive in the new environmental condition.

Question 5

What are the functions performed by the testis in human beings?

Medium

Solution

Verified by Toppr

Answer

Testes are the primary sex organs of a male reproductive system that lie outside the abdominal cavity in the scrotal sac. Each testis is divided into lobules by connective tissue and each lobule contains one to three seminiferous tubules which are the site for sperm formation. The large sustentacular cells that extend from the capsule to the lumen of the seminiferous tubule are called as Sertoli cells. They serve to support, nourish and regulate the development of cells undergoing spermatogenesis. The endocrine cells present in the space between seminiferous tubules are termed as interstitial cells or interstitial cells of Leydig. They serve to secrete androgen, testosterone, which is responsible for the development of male secondary sexual characters.

Answer

Testes are the primary sex organs of a male reproductive system that lie outside the abdominal cavity in the scrotal sac. Each testis is divided into lobules by connective tissue and each lobule contains one to three seminiferous tubules which are the site for sperm formation. The large sustentacular cells that extend from the capsule to the lumen of the seminiferous tubule are called as Sertoli cells. They serve to support, nourish and regulate the development of cells undergoing spermatogenesis. The endocrine cells present in the space between seminiferous tubules are termed as interstitial cells or interstitial cells of Leydig. They serve to secrete androgen, testosterone, which is responsible for the development of male secondary sexual characters.

Question 6

Why does menstruation occur?

Medium

Solution

Verified by Toppr

Answer

Explanation-

Menstrual cycle refers to the female reproductive cycle characterized by regularly occurring changes in the uterine lining and the loss of blood and tissue during this cycle.
The cycle includes egg maturation and preparation of the uterus for implantation by thickening of the endometrium under hormonal regulation. In absence of egg fertilization, egg rupture is followed by disintegration of the uterine lining (endometrium).
Since the uterine wall is rich in blood capillaries and tissues, its shedding off results in the release of blood and tissues which come out through the vagina in menses.

Answer

Explanation-

Menstrual cycle refers to the female reproductive cycle characterized by regularly occurring changes in the uterine lining and the loss of blood and tissue during this cycle.
The cycle includes egg maturation and preparation of the uterus for implantation by thickening of the endometrium under hormonal regulation. In absence of egg fertilization, egg rupture is followed by disintegration of the uterine lining (endometrium).
Since the uterine wall is rich in blood capillaries and tissues, its shedding off results in the release of blood and tissues which come out through the vagina in menses.

Question 7

What are the different methods of contraception?

Medium

Solution

Verified by Toppr

Answer

Answer-

Any approach used to prevent the conception of unwanted pregnancy refers to contraception. Major contraceptive methods are categorized as barrier methods, surgical and chemical methods.
Barrier methods are the physical devices that prevent conception by inhibiting the entry of sperms in the female genital tract. Example: condoms, diaphragms, cervical caps, etc.
Surgical methods include vasectomy (blocks vas deferens to prevent sperms from coming out) and tubectomy (blocks fallopian tubes to prevent the entry of eggs in it) in males and females respectively.
Chemical methods of contraception include any hormonal preparation that serves to alter the hormonal balance of the body to prevent egg maturation or fertilization. For example, oral and vaginal pills.
Other methods include intrauterine devices (inserted by a physician into the uterus to prevent implantation), medical termination of pregnancy, coitus interruptus, etc.

Answer

Answer-

Any approach used to prevent the conception of unwanted pregnancy refers to contraception. Major contraceptive methods are categorized as barrier methods, surgical and chemical methods.
Barrier methods are the physical devices that prevent conception by inhibiting the entry of sperms in the female genital tract. Example: condoms, diaphragms, cervical caps, etc.
Surgical methods include vasectomy (blocks vas deferens to prevent sperms from coming out) and tubectomy (blocks fallopian tubes to prevent the entry of eggs in it) in males and females respectively.
Chemical methods of contraception include any hormonal preparation that serves to alter the hormonal balance of the body to prevent egg maturation or fertilization. For example, oral and vaginal pills.
Other methods include intrauterine devices (inserted by a physician into the uterus to prevent implantation), medical termination of pregnancy, coitus interruptus, etc.

Question 8

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

Medium

Solution

Verified by Toppr

Answer

Answer-

Unicellular organism- The organisms with single-celled body organisation are referred to as unicellular organisms.

Being single-celled, cell division in these organisms gives rise to offspring (mainly asexual reproduction) and therefore, there is no need of special organ system for the process of reproduction.
For example, binary fission in Amoeba takes place by enlargement of the cell and increasing cell content followed by division of mother cell into two daughter cells, each of which is now offspring Amoeba.
Other methods of reproduction in unicellular organisms include fragmentation, fission, budding etc.

Multicellular organisms- Multicellular organisms consist of multiple cells which are organised into tissues, organs and organ systems. Owing to the complexity of their body organisation, they have specialised reproductive systems and reproduce by sexual reproduction.

Answer

Answer-

Unicellular organism- The organisms with single-celled body organisation are referred to as unicellular organisms.

Being single-celled, cell division in these organisms gives rise to offspring (mainly asexual reproduction) and therefore, there is no need of special organ system for the process of reproduction.
For example, binary fission in Amoeba takes place by enlargement of the cell and increasing cell content followed by division of mother cell into two daughter cells, each of which is now offspring Amoeba.
Other methods of reproduction in unicellular organisms include fragmentation, fission, budding etc.

Multicellular organisms- Multicellular organisms consist of multiple cells which are organised into tissues, organs and organ systems. Owing to the complexity of their body organisation, they have specialised reproductive systems and reproduce by sexual reproduction.

Question 9

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

Medium

Solution

Verified by Toppr

Answer

Reproduction is the production of offspring via the sexual or asexual method and thus, is responsible for the inheritance of genetic characters and to create variations. It includes DNA replication, the carrier of genetic information, and its transmission from parent to offspring.
This ensures the inheritance of species-specific genetic characters from one generation to next and thereby maintain the species stability. Also, the ratio of death and birth maintains species stability.
Since reproduction is the only method to transmit DNA from one generation to next and to give birth to offspring, it is inevitable for maintaining species stability.

Answer

Reproduction is the production of offspring via the sexual or asexual method and thus, is responsible for the inheritance of genetic characters and to create variations. It includes DNA replication, the carrier of genetic information, and its transmission from parent to offspring.
This ensures the inheritance of species-specific genetic characters from one generation to next and thereby maintain the species stability. Also, the ratio of death and birth maintains species stability.
Since reproduction is the only method to transmit DNA from one generation to next and to give birth to offspring, it is inevitable for maintaining species stability.

Question 10

What could be the reasons for adopting contraceptive methods?

Medium

Solution

Verified by Toppr

Answer

Answer:

Contraceptive methods include any approach to prevent conception; for example, oral contraceptive pills, surgical methods (vasectomy, tubal ligation), contraceptive implants, diaphragm, cervical cap, condoms, intrauterine devices etc.
These methods are adopted for protection against sexually transmitted diseases, to have a sufficient gap between two successive childbirth to ensure better health of mother and children, to restrict the number of kids, to enjoy reproductive health and to control exponential population growth.

Answer

Answer:

Contraceptive methods include any approach to prevent conception; for example, oral contraceptive pills, surgical methods (vasectomy, tubal ligation), contraceptive implants, diaphragm, cervical cap, condoms, intrauterine devices etc.
These methods are adopted for protection against sexually transmitted diseases, to have a sufficient gap between two successive childbirth to ensure better health of mother and children, to restrict the number of kids, to enjoy reproductive health and to control exponential population growth.

NCERT Solutions for Class 10 Biology Chapter 8 : How do Organisms Reproduce?

Access NCERT Solutions for Class 10 Biology Chapter 8 : How do Organisms Reproduce?

NCERT Solutions for Class 10 Biology Chapter 8 : How do Organisms Reproduce?

NCERT Solutions for Chapter 8 Science Class 10 - How do Organisms Reproduce?

Key Features of NCERT Solutions for How do Organisms Reproduce Class 10 Solutions

Frequently Asked Questions on NCERT Class 10 Biology Chapter 8 : How do Organisms Reproduce?