Meiosis: making egg and sperm cells with half the chromosomes

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Ari reads a card for a model body cell. Which words describe a cell that has two matching sets of chromosomes?

   • Diploid, written n
   • Haploid, written n
   • Diploid, written 2n
   • Haploid, written 2n
2. 2.

   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?

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

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?

   • 46 chromosomes
   • 92 chromosomes
   • 23 chromosomes
   • 22 chromosomes

5. 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.

6. 4.

   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?

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

7. Use this

   Flow card (model, not to scale):

8. 5.

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

   • Four cells
   • One cell
   • Eight cells
   • Two cells
9. 6.

   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
   • One division
   • Three divisions
   • Four divisions, one for each finished cell

10. 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: ?

11. 7.

    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
    • Two sets, but the sperm cell's chromosomes are lost
    • One set, the same as each gamete
12. 8.

    Ren studies four pictures of a cell with 4 chromosomes. Which picture shows the finished haploid cells at the end of meiosis?

    • Picture D: four cells with 4 single rods each
    • Picture A: one cell with 4 X-shaped chromosomes
    • Picture C: four cells with 2 single rods each
    • Picture B: two cells with 2 X-shaped chromosomes each
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 members of each matching pair
    • The two sister chromatids of each X

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