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

    Groups: Binary fission · Multiple fission · Budding · Fragmentation

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

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

  3. 3.Why does bread mold make spores with thick walls round them?

    • a) The wall protects the spore until it meets a moist surface and can grow
    • 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 holds the food store the new individual grows on

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

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

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

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

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

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

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

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

  8. 8.If the egg released this month is not fertilized, what happens to the thick lining the uterus has prepared?

    • a) It breaks down and leaves through the vagina as blood and mucus
    • b) It is absorbed back into the ovaries
    • c) It stays in place until the next egg is fertilized
    • d) It thickens further and holds the unfertilised egg

Answer key — Grade 10 Science — How organisms reproduce

  1. 1. Amoeba → Binary fission; Leishmania → Binary fission; Plasmodium → Multiple fission; Yeast → Budding; Hydra → Budding; Spirogyra → Fragmentation
  2. 2. d) Variation gives a species a chance of surviving a change in its niche
  3. 3. a) The wall protects the spore until it meets a moist surface and can grow
  4. 4. a) So that two of them joining restore the usual number rather than doubling it
  5. 5. 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
  6. 6. d) Sperm formation needs a temperature lower than the rest of the body's
  7. 7. a) HIV-AIDS
  8. 8. a) It breaks down and leaves through the vagina as blood and mucus