Lesson 1 | Sexual Reproduction and Meiosis
Student Labs and Activities
Page
Appropriate For:
Launch Lab
8
all students
Content Vocabulary ELL
9
all students
Lesson Outline ELL
10
all students
MiniLab
12
all students
Content Practice A
13
AL
AL
AL
Content Practice B
14
AL
OL
BL
Language Arts Support
15
all students
Math Skills
17
all students
School to Home
18
all students
Key Concept Builders
19
Enrichment
23
Challenge
24
AL
AL
BL
Lesson Quiz A
25
AL
AL
AL
Lesson Quiz B
26
AL
OL
BL
AL
AL
AL
all students
Assessment
Teacher Support
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Answers (with Lesson Outlines)
AL Approaching Level
T2
OL On Level
BL Beyond Level
ELL English-Language Learner
Teacher evaluation will determine which activities to use or modify to meet any ELL student’s proficiency level.
Reproduction of Organisms
7
Name
Date
Launch Lab
Class
LESSON 1: 15 minutes
Why do offspring look different?
Unless you’re an identical twin, you probably don’t look exactly like any siblings you might
have. You might have differences in physical characteristics such as eye color, hair color, ear
shape, or height. Why are there differences in the offspring from the same parents?
Procedure
1. Read and complete a lab safety form.
2. Open the paper bag labeled Male
Parent, and, without looking, remove
three beads. Record the bead colors in
your Science Journal, and replace the
beads.
4. Repeat steps 2 and 3 for each member
of the group.
5. After each member has recorded his or
her bead colors, study the results. Each
combination of male and female beads
represents an offspring.
3. Open the paper bag labeled Female
Parent and remove three beads. Record
the bead colors and replace the beads.
Think About This
1. Compare your group’s offspring to another group’s offspring. What similarities or
differences do you observe?
3.
8
Key Concept Why might this type of reproduction be beneficial to an organism?
Reproduction of Organisms
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2. What caused any differences you observed? Explain.
Name
Date
Class
Content Vocabulary
LESSON 1
Sexual Reproduction and Meiosis
Directions: Explain the relationship between/among the terms in each group below.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Terms
How are these terms related?
egg, sperm
1.
fertilization, zygote
2.
diploid, haploid
3.
fertilization, sexual reproduction,
DNA
4.
homologous chromosomes, diploid
5.
DNA, meiosis, homologous
chromosomes
6.
meiosis, diploid, haploid
7.
Reproduction of Organisms
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Name
Date
Class
Lesson Outline
LESSON 1
Sexual Reproduction and Meiosis
A. What is sexual reproduction?
1.
produces an offspring when genetic materials from two
different sex cells combine.
a. The female sex cell, a(n)
, forms in an ovary.
b. The male sex cell, a(n)
, forms in a testis.
2. During a process called
, an egg cell and a sperm cell
join together. The new cell that forms is called a(n)
.
B. Diploid Cells
1. Organisms that reproduce sexually make two kinds of cells—
cells and sex cells.
2. Body cells are
; they have pairs of chromosomes.
3. If a zygote has too many or too few
, it will not develop
properly.
4. Different organisms have different
5.
of chromosomes.
C. Haploid Cells
1. Sex cells are
; they have only one chromosome from
each pair of chromosomes.
2. In
, one diploid cell divides and makes four haploid
cells.
D. The Phases of Meiosis
1. Meiosis involves two divisions of the nucleus and the
.
These divisions, known as meiosis I and meiosis II, result in four haploid cells.
2. During
, the reproductive cell grows and duplicates its
chromosomes.
3. During meiosis I, each pair of duplicated homologous chromosomes
.
4. After meiosis I, the two cells formed during this stage go through a second division
of the
sister
10
and cytoplasm called meiosis II. During meiosis II,
separate to produce four haploid cells.
Reproduction of Organisms
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are pairs of chromosomes that have genes for the same
traits arranged in the same order.
Name
Date
Class
Lesson Outline continued
E. Why is meiosis important?
1. Meiosis forms sex cells with the correct haploid number of
. This maintains the correct
number of chromosomes in organisms when sex cells join.
2. Meiosis creates genetic variation by producing
cells.
F. How do mitosis and meiosis differ?
1. During
and cell division, a body cell and its nucleus
divide once and produce two identical cells.
2. During
, a reproductive cell and its nucleus divide twice
and produce four cells––two pairs of identical haploid cells.
G. Advantages of Sexual Reproduction
1. Sexual reproduction produces
that have a new
combination of DNA. This results in genetic
individuals.
among
2. Genetic variation gives individuals within a population slight differences that
might be an advantage if the
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
3.
changes.
breeding has been used to develop desirable traits in
plants and animals.
H. Disadvantages of Sexual Reproduction
1. One disadvantage of sexual reproduction is that organisms have to grow and
develop until they are mature enough to produce
cells.
2. Another disadvantage is that searching for a mate takes time and energy and might
expose individuals to predators,
environmental conditions.
Reproduction of Organisms
, or harsh
11
Name
Date
MiniLab
Class
LESSON 1: 20 minutes
How does one cell produce four cells?
When a diploid cell goes through meiosis, it produces four haploid cells. How does
this happen?
Procedure
1. Read and complete a lab safety form.
2. Make a copy of the diagram by tracing
circles around a jar lid on your
paper. Label as shown.
3. Use chenille craft wires to make
red and blue duplicated chromosomes
Diploid cell
2.5 cm long and green and yellow
duplicated chromosomes 1.5 cm long.
Recall that a duplicated chromosome
has two sister chromatids connected at
the centromere.
4. Place the chromosomes in the diploid
cell.
5. Move one long chromosome and one
short chromosome into each of the
middle cells.
Meiosis I
Meiosis II
6. Separate the two strands of the
chromosomes, and place one strand
into each of the haploid cells.
Haploid cells
1. Describe What happened to the chromosomes during meiosis I? During meiosis II?
2. Think Critically Why are two haploid cells (sperm and egg) needed to form a zygote?
3.
12
Key Concept How does one cell form four cells during meiosis?
Reproduction of Organisms
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Analyze and Conclude
Name
Date
Class
Content Practice A
LESSON 1
Sexual Reproduction and Meiosis
Directions: On the line before each definition, write the letter of the term that matches it correctly. Each term
is used only once.
1. production of an offspring through the
combination of egg and sperm
A. diploid cell
B. egg
C. fertilization
2. female sex cell
3. male sex cell
D. haploid cell
E. homologous
chromosomes
F. meiosis
4. joining of egg and sperm
5. the cell formed by fertilization
G. sexual reproduction
H. sperm
I. zygote
6. body cell or zygote, which has pairs
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
of chromosomes
7. male or female sex cell that has only one
chromosome from each pair
8. process by which one diploid cell divides into
four haploid cells
9. two chromosomes that have genes for the same
traits in the same order
Directions: On the line before each statement, write T if the statement is true or F if the statement is false.
10. Sexual reproduction produces offspring that is identical to the parents.
11. The nucleus divides in meiosis I and again in meiosis II.
12. During meiosis, the number of chromosomes in each cell stays the same.
Reproduction of Organisms
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Name
Date
Class
Content Practice B
LESSON 1
Sexual Reproduction and Meiosis
Directions: Answer each question or respond to each statement on the lines provided.
1. Define sexual reproduction.
2. What are male and female sex cells, and where are they made?
3. Explain what a zygote is. Use the terms egg cell, sperm cell, and fertilization in your
explanation.
5. Which process divides one diploid cell and makes four haploid cells? How many times
does the nucleus divide during this process?
6. What are homologous chromosomes?
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Reproduction of Organisms
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4. Compare a diploid cell and a haploid cell. Include where each cell is located.
Name
Date
Language Arts Support
Class
LESSON 1
Writing Activity: Revisions
Learning the Skill
Few people get everything right the first time. When you draw a picture, you probably erase
and sketch it many times. A theater performance requires many rehearsals before it is ready
for an audience. In a similar way, the writing process involves more than one draft. After
you gather ideas, take notes, and develop an outline, you write a draft, which puts the ideas
together. Then it is time to revise. Revision takes a piece of writing to the next level. During
this step, you review your work to make sure your ideas will be clear to your readers. Multiple
revisions are often necessary. It might help to think of revisions on four different levels:
• Overall Structure—Readers can understand your writing more clearly if you combine
related ideas. As you review your writing, circle each main point in a different color.
Then underline each sentence that supports that point in the same color. If your
paragraph contains marks of several different colors, move sentences to the paragraph
they support. If you find sentences that are not circled or underlined, delete the
sentence or use it in a new paragraph.
• Paragraphs—Make sure the main idea in each paragraph is adequately supported.
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Several types of sentences can support a main idea. Use the following list to evaluate
the strength of each paragraph. If your review shows that an idea needs more support,
add one of the sentence types from this list.
Paragraph Number
Supporting Sentences:
Main Idea:
Detail:
Example:
Fact:
Quotation:
• Sentences—Review your sentence patterns. Are your sentences mostly short or long?
Do their beginnings vary, or do they start the same way? Some ways to add variety to
your sentences include
inserting a short sentence between two long ones;
combining two sentences into one longer, compound sentence;
changing the passive to the active tense to make the writing more vivid and concise.
• Word Choice—Review your draft again, checking for repeated words or words that are
too general. Highlight nouns, verbs, adjectives, and phrases you have used more than
once. Then use a thesaurus to find alternate words. Highlight general words and
replace them with more concise ones; for example, tree → oak; dog → beagle; red →
crimson.
Reproduction of Organisms
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Name
Date
Language Arts Support
Class
LESSON 1
Writing Activity: Revisions
Practicing the Skill
Directions: Read the following draft. Then answer each question or respond to each statement on the
lines provided.
Meiosis is a special type of cell division that produces eggs and sperm for sexual reproduction.
Mitosis is a different process by which cells divide. Meiosis is cell division that produces
eggs or sperm from certain cells in an organism’s reproductive system. Meiosis is a process
that only takes place in eukaryotes that reproduce sexually. Sexual reproduction only occurs
among some organisms.
1. What is the main idea of the paragraph?
2. Which two sentences do not fit the main idea of the paragraph? What do you think
the writer should do with these sentences? Explain why.
Revise the sentence below to eliminate the repetition.
Meiosis is cell division that produces eggs or sperm from certain cells in an organism’s
reproductive system.
4. Look at the sentence you revised in question 3. Three sentences start with the words
“Meiosis is.” Make an additional revision to the sentence above or another sentence to
vary the sentence structure.
Applying the Skill
Directions: Review a piece of writing that you have worked on for this class. Evaluate it using the four levels of
revisions outlined under Learning the Skill. Then use the suggested strategies to revise your draft. Exchange your
revised paper with a partner to find out whether your ideas are clear.
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Reproduction of Organisms
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3. The phrase “cell division that produces eggs and sperm” appears twice in this paragraph.
Name
Date
Class
Math Skills
LESSON 1
Use Proportions
A proportion is an equation that shows that two ratios are equal. When two ratios form
a proportion, the cross products are equal. In this example, the cross products are 2 × 10
and 4 × 5.
5
2 = ___
If __
, then 2 × 10 = 4 × 5.
10
4
If one of the numbers in a proportion is unknown, cross multiply to change the proportion
to an equation. Then solve the equation for the unknown number.
You know that 1 cell produces 2 daughter cells at the end of mitosis. How many daughter
cells will be produced by 19 cells?
Step 1 Use the information in the problem to write a proportion.
1
__
2
19
= ___
n
Step 2 Cross multiply to solve for the unknown number.
1 × n = 2 × 19
n = 38
Step 3 Use the solution to answer the question in the original problem situation.
The 19 cells will produce 38 daughter cells.
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Practice
1. If 7 cells go through mitosis, how
many daughter cells will be produced?
3. The egg of a type of frog is 1.5 mm
wide. If you place 12 eggs in a line,
what is the length of the line from end
to end?
Reproduction of Organisms
2. If 47 sex cells go through meiosis, how
many daughter cells will be produced?
4. For another type of frog, 3 eggs in a
row measure 6 mm across. What is the
length of a line of 12 eggs?
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Name
Date
Class
School to Home
LESSON 1
Sexual Reproduction and Meiosis
Directions: Use your textbook to answer each question.
1. The production of an offspring resulting from the combination of genetic
materials of two different cells is called sexual reproduction.
How is a zygote formed in sexual reproduction?
2. Diploid cells have pairs of chromosomes, whereas haploid cells have only
one chromosome from each pair.
Which cells are sex cells, diploid cells or haploid cells?
3. Meiosis and mitosis are similar processes in which an organism produces
new cells.
4. Meiosis produces cells that are not genetically identical to the parent cell.
What are the advantages and disadvantages of sexual reproduction?
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Reproduction of Organisms
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
What are the differences between the processes of meiosis and mitosis?
Name
Date
Class
Key Concept Builder
LESSON 1
Sexual Reproduction and Meiosis
Key Concept What is sexual reproduction, and why is it beneficial?
Directions: Work with a partner to answer each question or respond to each statement on the lines provided.
1. Name the type of reproduction that occurs when the genetic materials from two
different cells combine to produce an offspring.
2. What are egg cells?
3. What are sperm cells?
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4. Explain the relationship between fertilization and a zygote.
5. What happens to a zygote?
6. Compare the DNA of an offspring to the DNA of its parents.
7. Why do offspring from the same parents usually have a different set of traits?
Reproduction of Organisms
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Name
Date
Class
Key Concept Builder
LESSON 1
Sexual Reproduction and Meiosis
Key Concept What is the order of the phases of meiosis, and what happens in each phase?
Directions: On each line, write the term from the word bank that correctly completes each sentence. Some terms
may be used more than once or not at all.
diploid
haploid
homologous chromosomes
meiosis
mitosis
sister chromatids
1. In meiosis, one
cell divides to make four
cells.
2. A
cell has half the chromosomes of a
cell.
3. A
cell has pairs of chromosomes.
4. Pairs of chromosomes that are not identical but have genes for the same trait arranged
in the same order are
.
has one chromosome from the mother and
one chromosome from the father.
6. In
7. During
, the two chromosomes are always identical.
, two divisions of the nucleus and the cytoplasm
occur.
8. When a cell duplicates one chromosome, two
are formed.
9. During interphase of mitosis and meiosis, two
are formed
for each chromosome.
10. A reproductive cell goes through interphase before beginning
I, but not before
II.
11. Prophase I and Prophase II are stages in
.
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Reproduction of Organisms
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5. Each pair of
Name
Date
Class
Key Concept Builder
LESSON 1
Sexual Reproduction and Meiosis
Key Concept What is the order of the phases of meiosis, and what happens in each phase?
Directions: Work with a partner. On each line, write the term or phrase that correctly completes each sentence.
Meiosis I
Phase
Prophase I
Description
1. Chromosomes that are duplicated during
remain sister chromatids.
2.
join and form pairs.
3. The membrane surrounding the nucleus
Metaphase I
apart.
4. Homologous chromosome pairs align along the
of the cell.
5.
Anaphase I
fibers attach to each pair.
6. Pairs of duplicated
and are pulled toward opposite ends of the cell.
chromosomes separate
7.
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Telophase I
stay together.
8. A nuclear membrane forms around each group of chromosomes. The
cytoplasm divides forming
daughter cells.
9.
remain together.
Meiosis II
Phase
Prophase II
Description
10.
do not duplicate.
breaks apart.
Metaphase II
11. Sister chromatids
along the middle of the cell.
Anaphase II
12. Sister chromatids of each duplicated chromosome are
and move
to
Telophase II
.
13. A nuclear membrane forms around each set of chromatids, which are again
called
14. The cytoplasm divides, and
15. Each cell has
as the original cell.
Reproduction of Organisms
.
cells form.
the number of chromosomes
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Name
Date
Class
Key Concept Builder
LESSON 1
Sexual Reproduction and Meiosis
Key Concept Why is meiosis important?
Directions: Answer each question on the lines provided.
1. If a male organism has 40 chromosomes in each body cell, how many chromosomes
does a female of the same species have in each body cell?
2. How many homologous pairs of chromosomes does the male have?
3. How many chromosomes would be in a sperm cell and in an egg cell?
4. How many chromosomes would be in an offspring?
5. How many pairs of homologous chromosomes would be in an offspring?
6. What is the difference between a diploid cell and a haploid cell?
diploid, haploid, fertilized egg, and sex cells in your answer.
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Reproduction of Organisms
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7. How does meiosis help maintain diploid cells in offspring? Use the terms chromosomes,
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Class
Enrichment
LESSON 1
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Rescuing Native Plants
Most North American food crops are
not native. Instead, they were brought to
America by European settlers. Many of these
crops are not resistant to American diseases
and pests—but native plants often are.
That’s why native plants play an important
role in growing healthy food crops.
drier and hotter conditions than most
other species of rice. Such traits are
especially useful in areas that experience
droughts, or extended periods of belowaverage rainfall. The traits might also be
needed if Earth’s surface temperatures
continue to rise on a global level.
Breeding with Native Plants
Benefits Versus Costs
Scientists can breed native plants with
crop plants to produce hardier plants. For
example, if potatoes are threatened by
disease, scientists can cross potatoes with
a native plant that has traits that make it
naturally disease resistant. Using the same
technique, scientists can produce plants
that are more resistant to pests. Improved
resistance has environmental benefits as
well, because farmers can use less chemical
pesticide.
Some native plants are better able to
withstand the climatic conditions in
different parts of America. For example,
a wild rice plant grows on the banks of a
single stream in Texas. This plant, which is
in danger of becoming extinct, can survive
Most scientists agree that native plants
should be preserved. They point out that
the health of the planet depends on a high
level of species diversity. In addition, some
native plants might have unknown
medicinal or commercial value; if they
become extinct, these benefits are lost
forever.
However, other experts point out that
the cost of saving each native plant is
very high. They argue that society must
determine the potential value of each
species before paying the high cost of
saving that species. About 700 native plants
in the United States are endangered, or at
risk of becoming extinct. That’s nearly onefourth of all native plants in the country.
Applying Critical-Thinking Skills
Directions: Answer each question or respond to each statement.
1. Infer Why are native plants often resistant to the diseases and pests in their
native land?
2. Weigh Do you think that all native plants should be preserved, or should only
those plants that have value for people be preserved? Explain.
Reproduction of Organisms
23
Name
Challenge
Date
Class
LESSON 1
Sequencing Meiosis
The diagrams show the stages of meiosis in scrambled order. To the left of each diagram,
label and sequence the stages in the correct order. To the right of each diagram, include a
brief description of what happens during each stage.
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Reproduction of Organisms