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

Questions

1. 1. Why can't we usually see the chromosomes in a cell, even using a microscope?

   • They only become visible when a cell is dividing, and they need special stains.
   • Chromosomes are bigger than the cell.
   • Only animal cells have chromosomes.
   • Chromosomes are outside the nucleus.
   Check

2. 2. Do red blood cells contain chromosomes?

   • No, they have no nucleus.
   • Yes, 46 of them.
   • Yes, 23 of them.
   Check

3. 3. How many chromosomes are in most human body cells?

   • 92
   • 23
   • 12
   • 46 (23 pairs)
   Check

4. 4. How many chromosomes are in the cells of a fruit fly?

   • 23
   • 8
   • 40
   • 46
   Check

5. 5. What is a chromosome?

   • a long thread of DNA in the nucleus
   • a short length of DNA that affects one characteristic
   • a type of cell
   • a part of the cell membrane
   Check

6. 6. What is a gene?

   • a short length of DNA that affects a characteristic
   • a long thread of DNA in the nucleus
   • a type of cell
   • a part of the cytoplasm
   Check

7. 7. All fruit flies have a gene for wing shape in the same place on chromosome 2. But some have normal wings and some have tiny wings. What can explain this?

   • The tiny-winged flies have more chromosomes.
   • They have different versions of the wing shape gene.
   • Some fruit flies have no chromosome 2.
   • Wing shape is not controlled by genes.
   Check

8. 8. Two sisters have different eye colours, though everyone has eye colour genes in the same place on chromosome 15. Why?

   • One of them has no eye colour gene.
   • They have different versions of the eye colour genes.
   • They have different numbers of chromosomes.
   • Eye colour is not inherited.
   Check

9. 9. What shape is a DNA molecule?

   • a circle
   • a double helix, like a twisted ladder
   • a straight line
   • a cube
   Check

10. 10. What does DNA do?

    • It makes the cell green.
    • It carries the instructions for making and running the organism.
    • It stores food for the cell.
    • It controls what enters the cell.
    Check

11. 11. Which is the correct order from largest to smallest?

    • nucleus, gene, chromosome
    • nucleus, chromosome, gene
    • gene, chromosome, nucleus
    • chromosome, nucleus, gene
    Check

12. 12. The diagrams show a plant cell and an animal cell. Name the part labelled A.

    • cytoplasm
    • chloroplast
    • vacuole
    • nucleus
    Check

13. 13. The diagrams show a plant cell and an animal cell. Name the part labelled B.

    • cytoplasm
    • vacuole
    • nucleus
    • cell wall
    Check

14. 14. Where in a cell are the chromosomes found?

    • in the nucleus
    • in the cytoplasm
    • in the cell membrane
    • in the cell wall
    Check

15. 15. Do plant cells contain chromosomes?

    • Yes, in their nucleus.
    • No, only animal cells do.
    • Yes, in their cell wall.
    Check

16. 16. When a cell divides, all the DNA is copied first. Why is this important?

    • so the cell gets bigger
    • so the old DNA can be thrown away
    • so each new cell gets a complete set of instructions
    • so the cell can make more food
    Check

17. 17. Why do cells divide in a growing plant or animal?

    • to make food
    • to release energy
    • to grow and to repair damage
    • to get rid of waste
    Check