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NCERT Class 10 Science How do Organisms Reproduce?: In-text questions (page 126) Solutions

Step-by-step working for every question of In-text questions (page 126) in NCERT's Class 10 Science book, chapter “How do Organisms Reproduce?”, written by Shishya. Each question is in our own short words; open the NCERT chapter for the exact wording and figures.

1. In-text (page 126) Q1

   How is pollination different from fertilisation?

   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 gamete from pollen with the female gamete in the ovule.
   3. Pollination is a physical process that happens before fertilisation.
   4. Fertilisation is a biological process that results in the formation of a zygote.

   Answer: Pollination is the transfer of pollen to the stigma, while fertilisation is the fusion of gametes to form a zygote.

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2. In-text (page 126) Q2

   What is the role of the seminal vesicles and the prostate gland?

   1. The seminal vesicles are paired glands located behind the urinary bladder.
   2. They secrete a fluid rich in fructose and other nutrients.
   3. This fluid provides energy for the movement of sperm.
   4. The prostate gland is a single gland located below the urinary bladder.
   5. It secretes a milky alkaline fluid into the semen.
   6. This alkaline fluid neutralizes the acidic environment of the vagina.
      why?

      An acid and a base react to give a salt and water (neutralisation): the H⁺ ions of the acid and the OH⁻ ions of the base join to form water.

   7. Neutralization protects the sperm and helps them survive longer.
      why?

      An acid and a base react to give a salt and water (neutralisation): the H⁺ ions of the acid and the OH⁻ ions of the base join to form water.

   8. Together, these glands form the seminal fluid that surrounds the sperm.

   Answer: Seminal vesicles provide nutrients for sperm; prostate gland secretes alkaline fluid to neutralize acidity.

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3. In-text (page 126) Q3

   What changes are seen in girls at puberty?

   1. Puberty is the stage of life when the body matures and becomes capable of reproduction.
   2. In girls, the ovaries begin to produce the hormone oestrogen which drives these changes.
   3. The breasts develop and the nipples enlarge as part of the physical maturation.
   4. The hips widen to prepare the body for potential pregnancy and childbirth.
   5. Fat deposits increase in the hips, thighs, and breasts, changing the body shape.
   6. Menstruation begins, which is the monthly shedding of the uterine lining.
   7. Vaginal secretions appear to keep the reproductive tract clean and moist.
   8. Pubic and underarm hair starts to grow due to hormonal influence.
   9. Voice changes may occur, though typically less dramatic than in boys.
   10. Emotional changes and growth spurts in height are also common during this phase.

   Answer: Girls experience breast development, hip widening, fat deposition, onset of menstruation, vaginal secretions, growth of pubic and underarm hair, and emotional changes at puberty.

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4. In-text (page 126) Q4

   How does the embryo get nourishment inside the mother's body?

   1. The embryo is connected to the mother's uterus through a special structure called the placenta.
   2. The placenta contains many tiny finger-like projections called villi on the embryo side.
   3. These villi are surrounded by blood vessels from the mother's body on the other side.
   4. This arrangement provides a large surface area for the exchange of materials.
   5. Nutrients and oxygen from the mother's blood pass through the placenta to the embryo.
   6. Waste products like carbon dioxide from the embryo pass into the mother's blood to be removed.
   7. The placenta acts as the main organ for nourishing the developing embryo.

   Answer: The embryo gets nourishment from the mother's blood through the placenta, which exchanges nutrients and removes waste.

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5. In-text (page 126) Q5

   Does a copper-T protect a woman from sexually transmitted diseases?

   1. Copper-T is an intrauterine contraceptive device (IUD) placed inside the uterus.
   2. It works by preventing the implantation of a fertilized egg and creating a hostile environment for sperm.
   3. Sexually transmitted diseases (STDs) are caused by pathogens that enter the body through sexual contact.
   4. The Copper-T does not form a physical barrier to block the entry of these pathogens.
   5. Therefore, it does not provide protection against STDs.
   6. To prevent STDs, one must use barrier methods like condoms.

   Answer: No, Copper-T does not protect a woman from sexually transmitted diseases.

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