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Year 11 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.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) Warm water causes bacteria to develop resistance
    • b) Variation protects each individual from any change
    • c) Variation gives a species a chance of surviving a change in its niche
    • d) Asexual reproduction produces identical offspring

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

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

  3. 3.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 large surface for glucose and oxygen to pass across, and for wastes to pass back
    • c) A store of food the embryo draws on directly
    • d) A muscular wall that pushes nutrients through

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

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

  5. 5.Why do germ-cells carry half the chromosomes an ordinary body cell carries?

    • a) So that they are small enough to travel
    • b) So that each parent's variations stay separate in the offspring
    • c) So that they can divide more quickly than body cells
    • d) So that two of them joining restore the usual number rather than doubling it

  6. 6.A pistil is drawn below, cut down the middle, with a stamen beside it. Tap the part the pollen has to land on.

    Write the number of the part.

    1234

  7. 7.Sort each organism by the way the chapter says it reproduces.

    Groups: Binary fission · Multiple fission · Budding · Fragmentation

    • Hydra
    • Yeast
    • Spirogyra
    • Amoeba
    • Leishmania
    • Plasmodium

  8. 8.Why does bread mould make spores with thick walls round them?

    • a) The wall holds the food store the new individual grows on
    • b) The wall makes the spore heavy enough to fall to the ground
    • c) The wall stops the spore from dividing too early
    • d) The wall protects the spore until it meets a moist surface and can grow

Answer key — Year 11 Science — How organisms reproduce

  1. 1. c) Variation gives a species a chance of surviving a change in its niche
  2. 2. d) They have lost the capacity to produce seeds
  3. 3. b) A large surface for glucose and oxygen to pass across, and for wastes to pass back
  4. 4. b) Sperm formation needs a temperature lower than the rest of the body's
  5. 5. d) So that two of them joining restore the usual number rather than doubling it
  6. 6. 1 — The stigma
  7. 7. Amoeba → Binary fission; Leishmania → Binary fission; Plasmodium → Multiple fission; Yeast → Budding; Hydra → Budding; Spirogyra → Fragmentation
  8. 8. d) The wall protects the spore until it meets a moist surface and can grow