HOW DO ORGANISMS REPRODUCE: Short Answer Type Questions Class 10th Chapter 10 JKBOSE/NCERT
Short Answer Type Questions
Question 1. List and explain in brief three methods of contraception.
Ans: Three methods of contraception:
a) Barrier Methods: Barrier methods of contraception involve the use of physical barriers to prevent sperm from reaching the egg. Examples include condoms (male and female) and diaphragms.
b) Hormonal Methods: Hormonal methods of contraception use hormones to prevent ovulation, inhibit sperm motility, or create an unfavourable environment for fertilization and implantation. Examples include oral contraceptive pills, hormonal patches, injections, and hormonal intrauterine devices (IUDs).
c) Surgical Methods: Surgical methods of contraception are permanent and involve surgical procedures to prevent pregnancy. Two common methods are tubal ligation (for females) and vasectomy (for males).
Question 2. Name the two types of germ cells present in human beings. How do they structurally differ from each other? Give two differences.
Ans: The two types of germ cells present in human beings are:
a) Sperm Cells (Spermatozoa): Sperm cells are the male germ cells. They are produced in the testes through the process of spermatogenesis. Sperm cells are small, motile, and have a streamlined structure with a head, midpiece, and tail. The head contains genetic material (DNA) and is covered by a cap called the acrosome, which aids in penetrating the egg during fertilization.
b) Egg Cells (Ova or Oocytes): Egg cells are the female germ cells. They are produced in the ovaries through the process of oogenesis. Egg cells are larger and non-motile compared to sperm cells. They have a spherical structure and contain genetic material (DNA). Each month, during the menstrual cycle, one mature egg is released from the ovary in a process called ovulation.
Structural differences between sperm cells and egg cells:
Size: Sperm cells are smaller in size compared to egg cells.
Mobility: Sperm cells are highly motile and equipped with a tail for swimming towards the egg, while egg cells are non-motile.
Question 3. List the parts of the human male reproductive system which contribute fluid to the semen. State two advantages semen offers to the sperms.
Ans: Parts of the human male reproductive system that contribute fluid to semen:
The parts of the male reproductive system that contribute fluid to semen are:
a) Seminal Vesicles: Seminal vesicles secrete a fluid that contributes a significant portion of the volume of semen. This fluid contains fructose, prostaglandins, and other substances that provide energy and nourishment to sperm.
b) Prostate Gland: The prostate gland produces and secretes prostatic fluid, which forms a component of semen. The prostatic fluid contains enzymes, citric acid, zinc, and other substances that aid in sperm activation, nourishment, and neutralization of acidic conditions in the female reproductive tract.
Advantages of semen for sperm:
Nourishment: Semen provides nutrients and energy sources, such as fructose, to nourish and support the motility and survival of sperm.
Protection: The fluid components of semen help protect sperm from the acidic environment of the female reproductive tract, increasing their chances of reaching and fertilizing the egg.
Question 4. What are the male and female gonads called in human beings? Mention their functions.
Ans: Male and female gonads in human beings and their functions:
Male Gonads: The male gonads are called testes or testicles. Their primary function is to produce sperm cells (spermatogenesis) and male sex hormones, primarily testosterone. The testes are responsible for the production of mature sperm and are located in the scrotum outside the abdominal cavity.
Female Gonads: The female gonads are called ovaries. Their primary function is to produce egg cells (oogenesis) and female sex hormones, such as estrogen and progesterone. The ovaries release mature eggs during ovulation and are located in the pelvic cavity on either side of the uterus.
Question 5. Explain post-fertilization changes in plants.
Ans: Post-fertilization changes in plants:
After fertilization in plants, several changes occur:
Formation of Zygote: Fertilization results in the fusion of the male gamete (sperm) with the female gamete (egg) to form a zygote. The zygote is the first cell of the new sporophyte generation.
Development of Embryo: The zygote undergoes cell division and differentiation, leading to the development of an embryo within the seed. The embryo contains the future plant with its shoot (plumule) and root (radicle) systems.
Maturation of Ovule: The ovule, which housed the egg, changes and develops into a seed. The ovule wall forms the seed coat, protecting the embryo.
Formation of Fruit: In many plants, the ovary surrounding the ovule develops into a fruit. The fruit protects the seeds, aids in seed dispersal, and promotes the survival and germination of seeds.
Seed Dispersal: The mature seeds are dispersed from the parent plant through various means like wind, water, animals, or mechanical mechanisms. This dispersal allows the seeds to reach new locations for germination and growth.
These post-fertilization changes are crucial for the successful reproduction and propagation of plants.
Question 6. Define the term puberty. List two changes observed in girls at the time of puberty.
Ans: Puberty is the stage of development during which a child’s body undergoes significant changes, transitioning into the reproductive and sexual maturity of adulthood. It is characterized by the maturation of the reproductive organs, the development of secondary sexual characteristics, and the onset of fertility.
Two changes observed in girls at the time of puberty are:
Development of Breasts: The mammary glands in the breasts develop, leading to an increase in the size and shape of the breasts.
The onset of Menstruation: The menstrual cycle begins, indicating the onset of fertility. It involves the shedding of the uterine lining, resulting in vaginal bleeding.
Question 7. State differences between sperm and eggs of humans.
1. Sperms are the male reproductive cells or gametes.
2. They are produced in the testes through the process of spermatogenesis.
3. Sperms are smaller in size and highly motile, equipped with a tail (flagellum) that aids in swimming towards the egg.
4. They have a streamlined structure with a head that contains genetic material (DNA) and an acrosome, which helps in penetrating the egg during fertilization.
1. Eggs are the female reproductive cells or gametes.
2. They are produced in the ovaries through the process of oogenesis.
4. Eggs are larger in size and non-motile compared to sperms.
5. They have a spherical structure and contain genetic material (DNA).
6. Each month, during the menstrual cycle, one mature egg is released from the ovary through ovulation.
Size: Sperms are smaller, while eggs are larger.
Mobility: Sperms are highly motile, while eggs are non-motile.
Question 8. (i) What is fragmentation in an organism?
(ii) Name a multicellular organism which reproduces by this method.
Ans: (i) Fragmentation in organisms refers to the process of breaking or dividing the body of an organism into several pieces, each of which can grow into a new individual. Each fragment has the potential to regenerate and develop into a complete organism.
(ii) Planaria, a flatworm, is a multicellular organism that reproduces by fragmentation. If a planarian is cut into several pieces, each piece can regenerate and develop into a new complete planarian organism.
Question 9. Explain the following methods of contraception giving one example of each:
(i) Barrier method
(ii) Hormonal imbalance method
(iii) Surgical method.
Ans: Methods of contraception and examples:
(i) Barrier Method: Barrier methods of contraception involve the use of physical barriers to prevent sperm from reaching the egg. One example is the male condom
(ii) Hormonal Imbalance Method: Hormonal methods of contraception use hormones to prevent ovulation, inhibit sperm motility, or create an unfavourable environment for fertilization and implantation. One example is oral contraceptive pills
(iii) Surgical Method: Surgical methods of contraception are permanent and involve surgical procedures to prevent pregnancy. One example is tubal ligation, where the fallopian tubes are blocked or sealed to prevent the eggs from reaching the uterus. Another example is vasectomy.
Question 10. (i) List any four reasons for adopting contraceptive methods.
(ii) If a woman is using Copper-T, will it help in protecting her from sexually transmitted diseases? Why?
Ans: (i) Four reasons for adopting contraceptive methods:
Family Planning: Contraceptive methods allow individuals and couples to plan and space their pregnancies according to their desired family size and resources.
Preventing Unwanted Pregnancy: Contraception helps prevent unwanted pregnancies, especially in cases where individuals are not ready for parenthood due to various reasons such as education, career goals, financial stability, or personal circumstances.
Health and Well-being: Contraceptive methods contribute to the overall health and well-being of individuals by reducing the risk of maternal and infant mortality, complications associated with childbirth, and unsafe abortions.
Controlling and Managing Reproductive Health: Contraception gives individuals the ability to take control of their reproductive health. It allows them to make informed choices about their sexual and reproductive lives, including preventing sexually transmitted infections and promoting safer sexual practices.
(ii) Copper-T, also known as an intrauterine device (IUD), does not protect against sexually transmitted diseases (STDs). It is primarily used as a highly effective form of contraception for preventing pregnancy. However, it does not create a barrier to prevent the transmission of STDs. To protect against STDs, the use of barrier methods such as condoms is recommended.
Question 11. Write any three differences between binary fission and multiple fission.
Ans: Differences between binary fission and multiple fission
1. Binary fission is a method of asexual reproduction in which a single organism divides into two daughter cells, each having identical genetic material to the parent cell.
2. It is commonly observed in single-celled organisms like bacteria and protozoans.
3. The division occurs along a single plane, resulting in the formation of two equal-sized daughter cells.
1. Multiple fission is a method of asexual reproduction in which a single organism divides into multiple daughter cells, each with a portion of the genetic material of the parent cell.
2. It is commonly observed in certain protozoans like Plasmodium, which causes malaria.
4. The division occurs simultaneously along multiple planes, resulting in the formation of multiple daughter cells.
Question 12. (i) Explain the role of the placenta in the development of the human embryo.
(ii) Give examples of two bacterial and two viral sexually transmitted diseases. Name the most effective contraceptive which prevents the spread of such diseases.
Ans: (i) Role of the placenta in the development of the human embryo:
1. The placenta is an organ that develops during pregnancy and acts as a connection between the mother and the developing embryo.
2. It facilitates the exchange of nutrients, oxygen, and waste products between the mother and the embryo.
3. The placenta provides a barrier between the maternal and fetal bloodstreams, preventing their mixing while allowing the exchange of substances.
4. It produces hormones, such as human chorionic gonadotropin (hCG) and progesterone, which support the maintenance of pregnancy.
5. The placenta also acts as a protective barrier against certain harmful substances and pathogens, preventing them from reaching the developing embryo.
(ii) Examples of bacterial sexually transmitted diseases (STDs):
Examples of viral sexually transmitted diseases (STDs):
1. Human Immunodeficiency Virus (HIV)
The most effective contraceptive method that helps prevent the spread of such diseases is the correct and consistent use of condoms. Condoms act as a barrier, preventing direct contact between bodily fluids and reducing the risk of transmission of STDs.
Question 13. Write the full form of DNA. Name the part of the cell where it is located. Explain its role in the process of reproduction of the cell.
Ans: DNA stands for Deoxyribonucleic Acid. It is located in the nucleus of a cell and plays a crucial role in the process of cell reproduction.
DNA’s role in the process of cell reproduction:
1. DNA contains the genetic information that determines the characteristics and traits of an organism.
2. During cell reproduction, DNA replicates itself in a process called DNA replication.
3. The replicated DNA is then passed on to the daughter cells during cell division, ensuring that the genetic information is transmitted to the new cells.
4. DNA carries the instructions for the synthesis of proteins, which are essential for the structure and functioning of cells and the overall development and functioning of the organism.
Question 14. (a) Explain the terms:
(i) Implantation (ii) Placenta (iii) What is the average duration of human pregnancy?
Ans: (i) Implantation: Implantation refers to the attachment of the fertilized egg (embryo) to the lining of the uterus (endometrium).
(ii) Placenta: The placenta is an organ that develops during pregnancy and connects the developing embryo or fetus to the uterine wall.
(iii) The average duration of human pregnancy is around 40 weeks or 9 months.
Question 15. Define menstruation and menopause.
Ans: Menstruation: Menstruation refers to the monthly shedding of the lining of the uterus (endometrium) in females of reproductive age. It is accompanied by vaginal bleeding and occurs as a part of the menstrual cycle. Menstruation typically lasts for a few days to a week and marks the beginning of a new menstrual cycle.
Menopause: Menopause is a natural biological process that occurs in females usually between the ages of 45 and 55. It is defined as the permanent cessation of menstrual periods and marks the end of reproductive years. During menopause, hormonal changes lead to the cessation of ovulation and the decline in reproductive function. It is often associated with symptoms such as hot flashes, mood changes, and changes in the reproductive system.