Download Name: Block: ______ Chapter 11 Introduction to Genetics

Name: ______________________________________
Block: _________
Chapter 11 Introduction to Genetics
Homework Packet 3
Section 11-4 Meiosis (pages 275-278)
This section explains how gametes form in the process of meiosis. It also explains how meiosis is different
from mitosis.
Chromosome Number (page 275)
1. The cells in an adult human have two versions of each chromosome. For instance, each of his or her cells
has two sex chromosomes, two chromosome 3s, two chromosome 15s, and so on. This kind of cell, with two
versions of every chromosome, is called _____ploid.
2. The cell at the center of a grain of plant pollen only has one version of each chromosome. It has only one
sex chromosome, one chromosome #1, one chromosome #2, and so on. This kind of cell, with only one
version of every chromosome, is called _____ploid.
3. Identify each of the following as being haploid or diploid cells:
a. 25 kinds of chromosomes. 50 chromosomes in each cell. _______
b. 3 kinds of chromosomes. 3 chromosomes in each cell. ______
c. 18 kinds of chromosomes. 18 chromosomes in each cell. ______
d. 7 kinds of chromosomes. 14 chromosomes in each cell. ______
e. 23 kinds of chromosomes. 46 chromosomes in each cell. ______
f. 148 kinds of chromosomes. 148 chromosomes in each cell. ______
4. What you see below are karyotypes, images of all the chromosomes found in a single cell. One of these
two cells (A or B) is diploid, and one (A or B) is haploid. Which is which?
Which is the diploid cell? __
Which is the haploid cell? __
5. A scientist isolates a cell from a mosquito. The cell has 3 different kinds of chromosomes, with two copies
of each, for a total of 6 chromosomes. Is this a diploid cell or a haploid cell? ________
6. A scientist isolates an egg cell from a pea plant. The cell has 7 different kinds of chromosomes, with one
copy of each, for a total of 7 chromosomes. Is this a diploid cell or a haploid cell? ________
7. A scientist isolates a gamete from a shrimp. The cell has 127 different kinds of chromosomes, with one
copy of each, for a total of 127 chromosomes. Is this a diploid cell or a haploid cell? ________
8. A scientist isolates a muscle cell from a pigeon. The cell has 40 different kinds of chromosomes, with one
copy of each, for a total of 40 chromosomes. Is this a diploid cell or a haploid cell? ________
1
9. The diagram below provides information about a carrot cell.
A normal diploid carrot cell contains 18 chromosomes. Which of the following diagrams correctly illustrates
the number of chromosomes in new cells produced in asexual reproduction (mitosis)?
A.
B.
C.
D.
Phases of Meiosis (pages 275-277)
10. During meiosis, how many divisions does the cell go through? ________________________
11. How many cells are formed at the end of meiosis? ______________________
12. What results from the process of crossing-over during meiosis? __________________________________
_____________________________________________________________________________________
Gamete Formation (page 278)
Match the products of meiosis with the descriptions.
Description
________ 13. Haploid gametes produced in males
Product of Meiosis
a. eggs
________ 14. Haploid gametes produced in females
b. sperm
________ 15. Cells produced in females that do not participate in reproduction
c. polar bodies
Comparing Mitosis and Meiosis (page 278)
16. Compare the number and type of cells that result from meiosis and mitosis. ________________________
_____________________________________________________________________________________
2
17. For each of the following cells, state how many chromosomes each daughter cell would have
if the cell underwent mitosis or meiosis.
Chromosome Number of
Chromosome Number in
Chromosome Number in
Dividing Cell
Each Daughter Cell
Each Daughter Cell
Produced by MITOSIS
Produced by MEIOSIS
2n
n
16
8
32
40
2n
18. Identify each of the cells in the diagram by stage of meiosis.
3
19.
a. If an organism has 17 different kinds of chromosomes, how many chromosomes are
found in each of its normal diploid cells? _____
b. How many chromosomes are found in its gametes? _____
c. After two of those gametes fertilize each other, how many chromosomes will the
zygote have? ____
20. Which of these is NOT true of gametes?
a. They do not contain homologous chromosomes.
b. Sperm and egg cells are examples of gametes.
c. Gametes are created by meiosis.
d. Gametes are created by mitosis.
21. Why is crossing-over important for organisms that reproduce sexually?
a. It makes sure their homologous chromosomes don’t stick together.
b. Each gamete and each offspring is genetically unique, so the whole population winds
up very genetically diverse.
c. It makes sure that gametes are haploid.
d. It gets rid of bad mutations before they can hurt the offspring.
22. In which phase of meiosis do each of these events occur?
a. The chromosomes of a diploid cell condense and become visible. ________
b. The cell membrane “squeezes in” and pinches off, dividing the cytoplasm to create four total
cells. ____________
c. Two nuclear membranes re-form. ____________
d. Homologous chromosomes are pulled apart by spindles. ____________
e. Paired homologous chromosomes line up down the center of the cell. _____________
f. The cell membrane “squeezes in” and pinches off, dividing the cytoplasm to create two total
cells. _____________
g. The cell conducts its normal metabolic activities. _____________
h. The chromosomes of two haploid cells condense and become visible. _____________
i. Unpaired chromosomes line up down the center of a cell. ____________
j. Sister chromatids are pulled apart by spindles. _____________
k. DNA replicates. _____________
l. Four nuclear membranes re-form. _____________
m. Crossing-over occurs. _____________
23. What is the name of the process illustrated here? ____________________
4