Meiosis: making egg and sperm cells with half the chromosomes

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   The front of the card reads n. The back is blank. Bo makes a flash card for the letter n. Which meaning belongs on the back?

   • One set of chromosomes, as in an egg or sperm cell
   • Two sets of chromosomes, as in a body cell
   • The number of cells made by one division
   • Two copies of one chromosome joined together
2. 2.

   Four cells (model, not to scale). Body cells of this animal have 4 chromosomes, drawn as 2 matching pairs. Esme looks at four cells from a model animal whose body cells have 4 chromosomes. Which cell is haploid?

   • Cell Q: 2 chromosomes, one from each pair
   • Cell R: 2 chromosomes that are a matching pair
   • Cell S: 8 chromosomes in 4 matching pairs
   • Cell P: 4 chromosomes in 2 matching pairs

3. Read this first

   Count card

   a human body cell has 46 chromosomes. An egg cell has ? chromosomes. Table: Count card; columns cell and chromosomes; rows body cell 46, egg cell ?.

4. 3.

   A human body cell has 46 chromosomes. Jun wants the number in one egg cell. What is it?

   • 92 chromosomes
   • 46 chromosomes
   • 22 chromosomes
   • 23 chromosomes
5. 4.

   Kira reads that a body cell of a model animal has 6 chromosomes. How many chromosomes are in one sperm cell of that animal?

   • 12 chromosomes
   • 6 chromosomes
   • 2 chromosomes
   • 3 chromosomes

6. Count card (model)

   Sperm cell, 5 chromosomes. Egg cell, 5 chromosomes. The two cells join in fertilization to make a new cell (a zygote) with ? chromosomes.

7. 5.

   In a model animal, a sperm cell with 5 chromosomes joins an egg cell with 5 chromosomes. How many chromosomes does the new cell have, asks Luz?

   • 15 chromosomes
   • 20 chromosomes
   • 10 chromosomes
   • 5 chromosomes

8. Use this

   Flow card (model, not to scale):

9. 6.

   One body cell goes through the whole of meiosis. How many cells does Milo count at the end?

   • Two cells
   • Eight cells
   • One cell
   • Four cells
10. 7.

    Noah counts the divisions in meiosis, from the starting cell to the finished cells. How many divisions are there?

    • Two divisions, one after the other
    • Four divisions, one for each finished cell
    • One division
    • Three divisions

11. Flow card (model, not to scale)

    An egg cell with 1 set of 3 chromosomes and a sperm cell with 1 set of 3 chromosomes join in fertilization to make a new cell (a zygote). Sets in the new cell: ?

12. 8.

    An egg cell and a sperm cell join in fertilization. How many sets of chromosomes does the new cell hold, asks Pia?

    • Four sets, doubled again
    • Two sets, the same as a body cell
    • One set, the same as each gamete
    • Two sets, but the sperm cell's chromosomes are lost
13. 9.

    Tala studies picture R, taken during the first division of meiosis. Which parts are being pulled to opposite ends?

    • The spindle fibers themselves
    • The two nuclei of the cell
    • The two sister chromatids of each X
    • The two members of each matching pair

14. Use this

    Picture S (model, not to scale): one of the cells made by the first division. It holds 2 chromosomes that do not match each other. Each X has split into 2 single rods. At each end sit 2 single rods.

15. 10.

    Zee studies picture S, taken during the second division of meiosis. Which parts are being pulled to opposite ends?

    • The two nuclei of the cell
    • The two members of each matching pair
    • The two cells made last time
    • The two sister chromatids of each chromosome