SCIENCE-10TH CBSE ANSWER KEY

HOW DO ORGANISMS REPRODUCE(8-10)
Question 7:How is the process of pollination different from fertilization?
Answer: Pollination is the process of transfer of pollens from anther to stigma. It occurs with the help of certain pollinators such as air, water, birds, or some insects.
Fertilization, on the other hand, is the fusion of the male and female gametes. It occurs inside the ovule and leads to the formation of zygote.
Question 8:
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 9:
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 10:
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.

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