Year 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.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 gives a species a chance of surviving a change in its niche
- c) Asexual reproduction produces identical offspring
- d) Variation protects each individual from any change
2.Banana, orange, rose and jasmine are raised by vegetative propagation. What makes it the method of choice for them?
- a) They have lost the capacity to produce seeds
- b) Their seeds produce plants that flower too early
- c) Their flowers cannot be pollinated by insects
- d) Their seeds take too long to germinate
3.Put the stages of fertilisation in a flowering plant in order, starting with "Pollen lands on a suitable stigma".
- The ovule takes a tough coat and becomes a seed
- A tube grows out of the pollen grain and travels down the style
- The male germ-cell fuses with the egg cell in the ovule
- The ovary ripens into a fruit
- The zygote divides again and again to form an embryo
- Pollen lands on a suitable stigma
4.Why does bread mould make spores with thick walls round them?
- a) The wall stops the spore from dividing too early
- b) The wall makes the spore heavy enough to fall to the ground
- c) The wall holds the food store the new individual grows on
- d) The wall protects the spore until it meets a moist surface and can grow
5.Which of these is a viral infection that can be passed on during the sexual act, according to the chapter?
- a) Goitre
- b) Gonorrhoea
- c) Syphilis
- d) HIV-AIDS
6.Put these stages in order, starting with "One of the ovaries releases an egg".
- The egg travels along the oviduct
- One of the ovaries releases an egg
- The embryo is implanted in the lining of the uterus
- The zygote divides into a ball of cells
- A sperm meets the egg in the oviduct
7.Match each part to the job it does.
- The testes
- The vas deferens
- The ovaries
- The oviduct
- The placenta
- Make the sperms
- Passes glucose and oxygen from the mother to the embryo
- Carries the sperms from the testes
- Make the eggs
- Carries the egg towards the uterus
8.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 large surface for glucose and oxygen to pass across, and for wastes to pass back
- d) A muscular wall that pushes nutrients through
Answer key — Year 10 Science — How organisms reproduce
- 1. b) Variation gives a species a chance of surviving a change in its niche
- 2. a) They have lost the capacity to produce seeds
- 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. d) The wall protects the spore until it meets a moist surface and can grow
- 5. d) HIV-AIDS
- 6. 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
- 7. 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
- 8. c) A large surface for glucose and oxygen to pass across, and for wastes to pass back