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Class 10 Science — How organisms reproduce

Tell the asexual modes apart by the organism that uses each, follow pollen from stigma to seed and an egg from ovary to implantation, and say why variation is worth the cost of two parents.

Name: ________________________

  1. 1.Match each part to the job it does.

    • The testes
    • The vas deferens
    • The ovaries
    • The oviduct
    • The placenta
    • Carries the sperms from the testes
    • Carries the egg towards the uterus
    • Make the sperms
    • Passes glucose and oxygen from the mother to the embryo
    • Make the eggs

  2. 2.A population of bacteria lives in temperate water, and the water warms. Most die; a few carrying a heat-resistant variation live and multiply. What does this show?

    • a) Variation protects each individual from any change
    • b) Warm water causes bacteria to develop resistance
    • c) Asexual reproduction produces identical offspring
    • d) Variation gives a species a chance of surviving a change in its niche

  3. 3.Put the stages of fertilisation in a flowering plant in order, starting with "Pollen lands on a suitable stigma".

    • The male germ-cell fuses with the egg cell in the ovule
    • The ovule takes a tough coat and becomes a seed
    • The ovary ripens into a fruit
    • Pollen lands on a suitable stigma
    • The zygote divides again and again to form an embryo
    • A tube grows out of the pollen grain and travels down the style

  4. 4.Put these stages in order, starting with "One of the ovaries releases an egg".

    • One of the ovaries releases an egg
    • The zygote divides into a ball of cells
    • A sperm meets the egg in the oviduct
    • The embryo is implanted in the lining of the uterus
    • The egg travels along the oviduct

  5. 5.What does the placenta's structure — villi on the embryo's side, blood spaces on the mother's — give the embryo?

    • a) A barrier that keeps the mother's blood entirely separate
    • b) A store of food the embryo draws on directly
    • c) A muscular wall that pushes nutrients through
    • d) A large surface for glucose and oxygen to pass across, and for wastes to pass back

  6. 6.Which of these is a viral infection that can be passed on during the sexual act, according to the chapter?

    • a) HIV-AIDS
    • b) Goitre
    • c) Syphilis
    • d) Gonorrhoea

  7. 7.Why do the testes lie in the scrotum, outside the abdominal cavity?

    • a) There is no room for them inside the abdomen
    • b) It keeps them away from the urinary bladder
    • c) It shortens the path the sperms have to travel
    • d) Sperm formation needs a temperature lower than the rest of the body's

  8. 8.Banana, orange, rose and jasmine are raised by vegetative propagation. What makes it the method of choice for them?

    • a) Their seeds produce plants that flower too early
    • b) They have lost the capacity to produce seeds
    • c) Their flowers cannot be pollinated by insects
    • d) Their seeds take too long to germinate

Answer key — Class 10 Science — How organisms reproduce

  1. 1. The testes → Make the sperms; The vas deferens → Carries the sperms from the testes; The ovaries → Make the eggs; The oviduct → Carries the egg towards the uterus; The placenta → Passes glucose and oxygen from the mother to the embryo
  2. 2. d) Variation gives a species a chance of surviving a change in its niche
  3. 3. 1. Pollen lands on a suitable stigma 2. A tube grows out of the pollen grain and travels down the style 3. The male germ-cell fuses with the egg cell in the ovule 4. The zygote divides again and again to form an embryo 5. The ovule takes a tough coat and becomes a seed 6. The ovary ripens into a fruit
  4. 4. 1. One of the ovaries releases an egg 2. The egg travels along the oviduct 3. A sperm meets the egg in the oviduct 4. The zygote divides into a ball of cells 5. The embryo is implanted in the lining of the uterus
  5. 5. d) A large surface for glucose and oxygen to pass across, and for wastes to pass back
  6. 6. a) HIV-AIDS
  7. 7. d) Sperm formation needs a temperature lower than the rest of the body's
  8. 8. b) They have lost the capacity to produce seeds