PAGE 114 – QUESTIONS & ANSWERS
Q1. What is the importance of DNA copying in reproduction?
Answer:
DNA copying is important because:
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It ensures that genetic information is passed from parents to offspring.
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It maintains similar body design and characteristics in the next generation.
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It also introduces variations, which help in the survival and evolution of species.
Q2. Why is variation beneficial to the species but not necessarily for the individual?
Answer:
Variation helps a species survive changes in the environment.
For example, if climate or temperature changes, some individuals with useful variations survive.
But variation may not help the same individual because:
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It might not provide immediate advantage.
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Some variations may even be harmful.
Example: If temperatures rise suddenly, heat-resistant bacteria survive, others die.
PAGE 119 – QUESTIONS & ANSWERS
Q1. How does binary fission differ from multiple fission?
| Binary Fission | Multiple Fission |
|---|---|
| One parent cell divides into two equal daughter cells |
One parent cell divides into many daughter cells |
| Example: Amoeba, Leishmania | Example: Plasmodium |
Q2. How will an organism be benefited if it reproduces through spores?
Answer:
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Spores can survive harsh conditions because they have thick protective walls.
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They spread easily by wind or water.
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They reproduce quickly to form new individuals.
Example: Bread mould (Rhizopus)
Q3. Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Answer:
Complex organisms have:
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Highly specialised tissues and organs arranged in a fixed pattern.
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Cannot be divided into pieces without damaging vital organs.
Therefore, regeneration cannot form a complete individual.
Example: Humans cannot regrow full bodies.
Q4. Why is vegetative propagation practised for growing some types of plants?
Answer:
Vegetative propagation is used because:
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Plants grow faster and bear fruits earlier.
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New plants are genetically identical to parents (same qualities preserved).
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Useful for plants not producing seeds naturally.
Q5. Why is DNA copying an essential part of the process of reproduction?
Answer:
Because it ensures:
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Transfer of hereditary information to offspring.
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Development of new individuals similar to parents.
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Introduction of variations that support evolution.
PAGE 126 – QUESTIONS & ANSWERS
Q1. How is the process of pollination different from fertilisation?
| Pollination | Fertilisation |
|---|---|
| Transfer of pollen from anther to stigma | Fusion of male gamete & female gamete |
| Occurs by wind, water, insects |
Occurs inside ovule |
| No zygote formation | Zygote is formed |
Q2. What is the role of the seminal vesicles and the prostate gland?
Answer:
They produce fluid that mixes with sperms to form semen, which:
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Provides nutrition
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Helps transport the sperms easily
Q3. What are the changes seen in girls at the time of puberty?
Answer:
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Development of breasts
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Menstruation begins
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Growth of hairs in armpits & pubic region
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Widening of hips
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Oily skin and pimples
Q4. How does the embryo get nourishment inside the mother’s body?
Answer:
Through the placenta, which:
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Transfers oxygen & nutrients from mother’s blood to embryo
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Removes waste products from embryo’s blood
Q5. If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?
Answer:
No.
Copper-T prevents pregnancy by blocking the movement of sperms,
but it does not prevent STDs like AIDS or syphilis.
Condoms help prevent STDs.