Chapter 7: How do Organisms Reproduce?

Q1. What is the importance of reproduction?

Solution

Reproduction is important because:
• Ensures continuation of species
• Introduces variation in population
• Variation helps in adaptation to changing environment
• Without reproduction, species would become extinct

Q2. What is the difference between sexual and asexual reproduction?

Solution

Asexual reproduction:
• Only one parent involved
• No gamete formation
• No fertilization
• Offspring are identical (clones)
• Examples: Budding, fragmentation, binary fission

Sexual reproduction:
• Two parents involved
• Gametes are formed
• Fertilization occurs
• Offspring show variation
• More genetic diversity

Q3. What is binary fission? Give examples.

Solution

Binary fission is a type of asexual reproduction where a single parent cell divides into two equal halves.

Examples:
• Amoeba — divides into two
• Leishmania — longitudinal binary fission
• Bacteria — divide by binary fission
• Plasmodium — multiple fission

Q4. What is budding? Give examples.

Solution

Budding is a type of asexual reproduction where a new organism develops from an outgrowth (bud) on the parent.

Examples:
• Hydra — bud grows and detaches
• Yeast — reproduces by budding
• Sponge — can reproduce by budding

Q5. What is fragmentation? Give examples.

Solution

Fragmentation is a type of asexual reproduction where the body of an organism breaks into two or more fragments, each developing into a new organism.

Examples:
• Spargana (flatworm)
• Starfish — can regenerate from arm fragments
• Spirogyra — filament breaks into fragments

Q6. What is vegetative propagation? What are its advantages?

Solution

Vegetative propagation is a type of asexual reproduction in plants where new plants are produced from roots, stems, leaves, or buds.

Advantages:
• Faster growth than seed propagation
• Plants are genetically identical (uniform quality)
• Plants can be produced year-round
• Useful for plants that don't produce viable seeds

Examples: Potato (tuber), Ginger (rhizome), Sugarcane (stem), Bryophyllum (leaf buds)

Q7. What are the different methods of contraception?

Solution

Methods of contraception:
• Barrier method: Condoms, diaphragm (prevent sperm entry)
• Oral contraceptive pills: Prevent ovulation
• IUD (Intrauterine Device): Copper-T prevents implantation
• Surgical methods: Vasectomy (male), Tubectomy (female)
• Natural methods: Periodic abstinence, withdrawal
• Emergency contraception: Morning-after pill

Q8. What are the changes that occur during puberty in boys and girls?

Solution

Boys:
• Voice becomes deeper
• Muscles develop
• Facial hair grows
• Testosterone increases
• Shoulders broaden

Girls:
• Menstruation begins
• Breasts develop
• Hips widen
• Estrogen increases
• Body becomes more rounded

Q9. Why is reproductive health important?

Solution

Reproductive health is important because:
• Prevents sexually transmitted diseases (STDs)
• Ensures safe pregnancy and childbirth
• Reduces maternal and infant mortality
• Helps in family planning
• Promotes physical and mental well-being
• Awareness helps prevent unwanted pregnancies

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