Science 9 · Unit 7: Genes and inheritance · Cambridge Lower Secondary Science Stage 9

Questions

1. 1. How many chromosomes are in the nucleus of a human egg or sperm cell?

   • 92
   • 23
   • 12
   • 46
   Check

2. 2. What is a zygote?

   • a sperm cell with a tail
   • the new cell formed when a sperm and an egg fuse
   • an unfertilised egg
   • a type of chromosome
   Check

3. 3. A sperm cell with 23 chromosomes fertilises an egg cell with 23 chromosomes. How many chromosomes does the zygote have?

   • 2
   • 92
   • 46
   • 23
   Check

4. 4. Which sex chromosome do all human egg cells contain?

   • a Y chromosome
   • no sex chromosome
   • either X or Y
   • an X chromosome
   Check

5. 5. Which sex chromosomes can a human sperm cell contain?

   • always one X chromosome
   • either one X chromosome or one Y chromosome
   • always one Y chromosome
   • both an X and a Y chromosome
   Check

6. 6. A sperm cell with a Y chromosome fertilises an egg. What sex is the baby?

   • male (XY)
   • female (XX)
   Check

7. 7. What are egg cells and sperm cells called?

   • zygotes
   • embryos
   • chromosomes
   • gametes
   Check

8. 8. Egg cells are female gametes. What are sperm cells?

   • male gametes
   • female gametes
   Check

9. 9. What is the joining of a sperm cell and an egg cell called?

   • reproduction
   • germination
   • excretion
   • fertilisation
   Check

10. 10. Which part of a sperm cell produces swimming movements?

    • the cytoplasm
    • the nucleus
    • the cell membrane
    • the tail
    Check

11. 11. Which gamete has food reserves in its cytoplasm?

    • the egg cell
    • the sperm cell
    Check

12. 12. Why does an egg cell have food reserves in its cytoplasm?

    • to provide energy for the embryo after fertilisation
    • to help it swim
    • to make it lighter
    • to store chromosomes
    Check

13. 13. How does a sperm cell compare with an egg cell?

    • It is much smaller and can swim. The egg is large and doesn't move.
    • It is much bigger and can't move.
    • They are the same size and shape.
    • It has more chromosomes.
    Check

14. 14. What do a sperm cell and an egg cell have in common?

    • Both have a nucleus with 23 chromosomes, and a cell membrane.
    • Both have a tail.
    • Both have lots of food reserves.
    • Both have 46 chromosomes.
    Check

15. 15. Why is it useful that a sperm cell has only a small amount of cytoplasm?

    • It needs to store water.
    • It is small and light, so it can swim quickly.
    • It needs to feed the embryo.
    • It makes the sperm cell bigger.
    Check