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Chapter 26
Reproduction and Development
Table of Contents
Section 1 Animal Reproduction
Section 2 Human Reproduction
Section 3 Growth and Development
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Chapter 26
Section 1 Animal Reproduction
Bellringer
Do you know how birds, ants, humans, and sea
stars reproduce? Write down any differences that
you are aware of in how these animals reproduce.
Write your answers in your science journal.
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Chapter 26
Section 1 Animal Reproduction
Objectives
• Distinguish between asexual and sexual
reproduction.
• Explain the difference between external and internal
fertilization.
• Identify the three different types of mammalian
reproduction.
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Chapter 26
Section 1 Animal Reproduction
Asexual Reproduction
• In asexual reproduction, a single parent has
offspring that are genetically identical to the parent.
• Budding, fragmentation, and regeneration are all
ways in which a parent organism can produce
genetically identical offspring.
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Chapter 26
Section 1 Animal Reproduction
Sexual Reproduction
• In sexual reproduction, offspring are formed when
genetic information from more than one parent
combines.
• Sexual reproduction in animals usually requires two
parents—a male and a female.
• The female parent produces sex cells called eggs.
The male parent produces sex cells called sperm.
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Chapter 26
Section 1 Animal Reproduction
Sexual Reproduction, continued
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Chapter 26
Section 1 Animal Reproduction
Internal and External Fertilization
• External Fertilization is the process when the
sperm fertilizes the eggs outside the female’s body.
• Internal Fertilization is the process when the egg
and sperm join inside the female’s body.
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Chapter 26
Section 1 Animal Reproduction
Mammals
• Monotremes are mammals that lay eggs.
• Marsupials are mammals that give birth to
partially developed live young. Most marsupials
have pouches where their young continue to
develop after birth.
• Placental Mammals are nourished inside their
mother’s body before birth.
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Chapter 26
Section 2 Human Reproduction
Bellringer
You may have heard of cloning in recent news
stories. Do you think that cloning human beings
could be considered as a kind of reproduction? Why
or why not? What kind of reproduction is it?
Record your answers in your science journal.
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Chapter 26
Section 2 Human Reproduction
Objectives
• Identify the structures and functions of the male
and female reproductive systems.
• Describe two reproductive system problems.
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Chapter 26
Section 2 Human Reproduction
The Male Reproductive System
• The male reproductive system produces sperm and
delivers it to the female reproductive system.
• The testes are a pair of organs that make sperm and
testosterone.
• Testosterone is the main male sex hormone. It helps
regulate the production of sperm and the development
of male characteristics.
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Chapter 26
Section 2 Human Reproduction
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Chapter 26
Section 2 Human Reproduction
The Female Reproductive System
• The female reproductive system produces eggs,
nurtures fertilized eggs (zygotes), and gives birth.
• The two ovaries are the organs that make eggs.
• Ovaries also release estrogen and progesterone,
the main female sex hormones. These hormones
regulate the release of eggs and development of
female characteristics.
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Chapter 26
Section 2 Human Reproduction
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Chapter 26
Section 2 Human Reproduction
The Female Reproductive System, continued
• The Egg’s Journey During ovulation, an egg is
released from an ovary and passes into a fallopian
tube. If the egg is fertilized, the resulting zygote
enters the uterus.
• When a baby is born, he or she passes through the
vagina and emerges outside the body.
• The menstrual cycle is a series of monthly changes
that prepares the body for pregnancy.
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Chapter 26
Section 2 Human Reproduction
Menstrual Cycle and Uterine Lining
Click below to watch the Visual Concept.
Visual Concept
You may stop the video at any time by pressing
the Esc key.
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Chapter 26
Section 2 Human Reproduction
Multiple Births
• Twins, Triplets, Quadruplets, and More In every
1,000 births, there are about 30 sets of twins. In the
United States, there are about two sets of triplets in
every 1,000 births. Births of quintuplets or more
happen only once in about 53,000 births.
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Chapter 26
Section 2 Human Reproduction
Reproductive System Problems
• STDs A sexually transmitted disease (STD) is a
disease that can pass from one person to another
during sexual contact.
STD
Approx. # of new cases each year
Chlamydia
3 to 10 millon
Genital HPV
5.5 million
Genital herpes
1 million
Gonorrhea
650,000
Syphilis
70,000
HIV/AIDS
40,000 to 50,000
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Chapter 26
Section 2 Human Reproduction
Reproductive System Problems, continued
• Cancer Sometimes, cancer happens in reproductive
organs. Cancer is a disease in which cells grow at an
uncontrolled rate.
• Infertility In the United States, about 15% of married
couples have difficulty producing offspring. Many of
these couples are infertile, or unable to have children.
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Chapter 26
Section 3 Growth and Development
Bellringer
Name the stages of physical development that you
have passed through thus far in your life. Remember
that your growth and development began while you
were still in the uterus.
Record your thoughts in your science journal.
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Chapter 26
Section 3 Growth and Development
Objectives
• Summarize the processes of fertilization and
implantation.
• Describe the development of the embryo and
the fetus.
• Identify the stages of human development from
birth to death.
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Chapter 26
Section 3 Growth and Development
From Fertilization to Embryo
• A fertilized egg
(zygote) travels down
the fallopian tube toward
the uterus. Eleven to 12
days after fertilization,
the zygote has become
a tiny ball of cells called
an embryo. The embryo
implants itself in the
uterus.
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Chapter 26
Section 3 Growth and Development
From Embryo to Fetus
• The placenta is a
special two-way
exchange organ. It has a
network of blood vessels
that provides the embryo
with oxygen and nutrients
from the mother’s blood.
Wastes produced by the
embryo are removed in
the placenta.
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Chapter 26
Section 3 Growth and Development
From Embryo to Fetus, continued
• Weeks 1 and 2 Doctors commonly count the time of
a woman’s pregnancy as starting from the first day of
her last menstrual period.
• Weeks 3 and 4 In week 3, after fertilization, the
zygote moves to the uterus. As the zygote travels, it
divides many times. At the end of week 4, implantation
is complete and the woman is pregnant.
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Chapter 26
Section 3 Growth and Development
From Embryo to Fetus, continued
• Weeks 5 to 8 In this stage, the embryo becomes
surrounded by a thin membrane called the amnion. The
umbilical cord forms. The heart, brain, other organs,
and blood vessels start to form.
• Weeks 9 to 16 At week 9, the fetus may begin to
make tiny movements. After week 10, the embryo is
called a fetus. The fetus grows rapidly during this
stage.
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Chapter 26
Section 3 Growth and Development
From Embryo to Fetus, continued
• Weeks 17 to 24 By week 17, the fetus can make
faces. By week 23, the fetus’s movements may be
quite vigorous!
• Weeks 25 to 36 At about 25 or 26 weeks, the
fetus’s lungs are well developed. By the 32nd week,
the fetus’s eyes are open and perceive light through
the mother’s abdominal wall.
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Chapter 26
Section 3 Growth and Development
Pregnancy Overview
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Visual Concept
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the Esc key.
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Chapter 26
Section 3 Growth and Development
Birth
• A full-term pregnancy usually lasts about 40 weeks.
Typically, as birth begins, the mother’s uterus begins a
series of muscular contractions called labor. Usually,
these contractions push the fetus through the mother’s
vagina, and the baby is born.
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Chapter 26
Section 3 Growth and Development
From Birth to Death
• Infancy to Childhood Generally, infancy is the
stage from birth to age 2. Childhood—another
period of fast growth—lasts from age 2 to puberty.
• Adolescence The stage from puberty to
adulthood is adolescence. During puberty, a
person’s reproductive system becomes mature.
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Chapter 26
Section 3 Growth and Development
From Birth to Death, continued
• Adulthood From about age 20 to age 40, you will
be a young adult. Beginning around age 30,
changes associated with aging begin.
• The aging process continues in middle age
(between 40 and 65 years old). A person who is
more than 65 years old is considered an older adult.
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Chapter 26
Section 3 Growth and Development
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Chapter 26
Reproduction and Development
Concept Map
Use the terms below to complete the concept map on
the next slide.
fragmentation
reproduction
sexual reproduction
internal fertilization
an embryo
zygote
egg
budding
asexual reproduction
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Chapter 26
Concept Map
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Chapter 26
Concept Map
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End of Chapter 26 Show
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Chapter 26
Standardized Test Preparation
Reading
Read each of the passages. Then, answer the
questions that follow each passage.
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Chapter 26
Standardized Test Preparation
Passage 1 The male reproductive system is made up
of internal and external organs. The external organs of
this system are the penis and the scrotum. The scrotum
is a skin-covered sac that hangs outside the body.
Normal human body temperature is about 37°C.
Normal sperm production and development cannot take
place at that temperature.
Continued on the next slide
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Chapter 26
Standardized Test Preparation
Passage 1, continued Normal sperm production and
development takes place at lower temperatures. That is
why the testes rest in the scrotum, outside the body.
The scrotum is about 2°C cooler than the body. Inside
each testis are masses of tightly coiled tubes, called
seminiferous tubules, in which sperm are produced
when conditions are right.
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Chapter 26
Standardized Test Preparation
1. In this passage, what does the word external mean?
A not part of the body
B outside the body
C inside the body
D lasting a long time
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Chapter 26
Standardized Test Preparation
1. In this passage, what does the word external mean?
A not part of the body
B outside the body
C inside the body
D lasting a long time
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Chapter 26
Standardized Test Preparation
2. Which of the following statements is a fact
according to the passage?
F The temperature in the scrotum is higher than
body temperature.
G Testes are internal organs of the male
reproductive system.
H Normal sperm production cannot take place at
normal body temperature.
I Normal human body temperature is about 37°F.
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Chapter 26
Standardized Test Preparation
2. Which of the following statements is a fact
according to the passage?
F The temperature in the scrotum is higher than
body temperature.
G Testes are internal organs of the male
reproductive system.
H Normal sperm production cannot take place at
normal body temperature.
I Normal human body temperature is about 37°F.
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Chapter 26
Standardized Test Preparation
3. What are the tubes in which sperm are made called?
A testes
B scrotum
C seminiferous tubules
D external organs
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Chapter 26
Standardized Test Preparation
3. What are the tubes in which sperm are made called?
A testes
B scrotum
C seminiferous tubules
D external organs
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Chapter 26
Standardized Test Preparation
Passage 2 In a normal pregnancy, the fertilized egg
travels to the uterus and implants itself in the uterus’s
wall. But, in about 7 out of 1,000 pregnancies in the
United States, a woman has an ectopic pregnancy. The
term ectopic is from two Greek words meaning “out of
place.” In an ectopic pregnancy, the fertilized egg
implants itself in an ovary, a fallopian tube, or another
area of the female reproductive system that is not the
lining of the uterus.
Continued on the next slide
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Chapter 26
Standardized Test Preparation
Passage 2, continued Because the zygote cannot
develop properly outside of the uterus, an ectopic
pregnancy can be very dangerous for both the mother
and zygote. As the zygote grows, it causes the mother
pain and bleeding. For example, an ectopic pregnancy
in a fallopian tube can rupture the tube and cause
abdominal bleeding. If an ectopic pregnancy is not
treated quickly enough, the mother may die.
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Chapter 26
Standardized Test Preparation
1. In the passage, what does the term ectopic
pregnancy probably mean?
A a pregnancy that takes place at the wrong time
B a type of pregnancy that happens about 7 out of 100
times in the United States
C a type of pregnancy caused by a problem with a
fallopian tube
D a pregnancy in which the zygote implants itself in the
wrong place
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Chapter 26
Standardized Test Preparation
1. In the passage, what does the term ectopic
pregnancy probably mean?
A a pregnancy that takes place at the wrong time
B a type of pregnancy that happens about 7 out of 100
times in the United States
C a type of pregnancy caused by a problem with a
fallopian tube
D a pregnancy in which the zygote implants itself in the
wrong place
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Chapter 26
Standardized Test Preparation
2. Which of the following statements is a fact
according to the passage?
F Ectopic pregnancies take place in about 7% of all
pregnancies.
G The ectopic pregnancy rate in the United States is
less than 1%.
H Ectopic pregnancies take place in the uterus.
I An ectopic pregnancy is harmless.
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Chapter 26
Standardized Test Preparation
2. Which of the following statements is a fact
according to the passage?
F Ectopic pregnancies take place in about 7% of all
pregnancies.
G The ectopic pregnancy rate in the United States is
less than 1%.
H Ectopic pregnancies take place in the uterus.
I An ectopic pregnancy is harmless.
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Chapter 26
Standardized Test Preparation
Interpreting Graphics
Use these diagrams to answer the questions that
follow.
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Chapter 26
Standardized Test Preparation
1. Which diagram of cell division would produce
identical twins: A or B?
A diagram B, because each egg is fertilized by a
separate sperm cell
B both diagram A and diagram B, because twins
result in both cases
C diagram A, because a single fertilized egg
separates into two halves
D diagram B, because two eggs are released by
an ovary
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Chapter 26
Standardized Test Preparation
1. Which diagram of cell division would produce
identical twins: A or B?
A diagram B, because each egg is fertilized by a
separate sperm cell
B both diagram A and diagram B, because twins
result in both cases
C diagram A, because a single fertilized egg
separates into two halves
D diagram B, because two eggs are released by
an ovary
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Chapter 26
Standardized Test Preparation
2. Which of the following could describe fraternal
twins?
F both boys
G both girls
H one girl and one boy
I any of these combinations
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Chapter 26
Standardized Test Preparation
2. Which of the following could describe fraternal
twins?
F both boys
G both girls
H one girl and one boy
I any of these combinations
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Chapter 26
Standardized Test Preparation
3. Which diagram of cell division could explain
triplets, two of whom are identical and one of
whom is fraternal?
A diagram A
B diagram B
C either diagram A or diagram B
D neither diagram A or diagram B
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Chapter 26
Standardized Test Preparation
3. Which diagram of cell division could explain
triplets, two of whom are identical and one of
whom is fraternal?
A diagram A
B diagram B
C either diagram A or diagram B
D neither diagram A or diagram B
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Chapter 26
Standardized Test Preparation
Math
Read each question, and choose the best answer.
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Chapter 26
Standardized Test Preparation
1. Identify the group that contains equivalent fractions,
decimals, and percents.
A 7/10, 0.7, 7%
B 1/2, 0.5, 50%
C 3/8, 0.38, 38%
D 3/100, 0.3, 33%
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Chapter 26
Standardized Test Preparation
1. Identify the group that contains equivalent fractions,
decimals, and percents.
A 7/10, 0.7, 7%
B 1/2, 0.5, 50%
C 3/8, 0.38, 38%
D 3/100, 0.3, 33%
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Chapter 26
Standardized Test Preparation
2. A geologist was exploring a cave. She spent 2.7 h
exploring on Saturday and twice as many hours
exploring on Sunday. Which equation could be used to
find n, the total number of hours the geologist spent
exploring the cave on those 2 days?
F n  2  2.7
G n  2.7  (2  2.7)
H n  2.7  2.7  2
I n  2  2.7
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Chapter 26
Standardized Test Preparation
2. A geologist was exploring a cave. She spent 2.7 h
exploring on Saturday and twice as many hours
exploring on Sunday. Which equation could be used to
find n, the total number of hours the geologist spent
exploring the cave on those 2 days?
F n  2  2.7
G n  2.7  (2  2.7)
H n  2.7  2.7  2
I n  2  2.7
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Chapter 26
Standardized Test Preparation
3. Which of the following story problems can be solved
by the equation below?
(60  70  68  80  x)  5  70
A The heights of four buildings in South Braintree are
60 ft, 70 ft, 68 ft, and 80 ft. Find x, the average height of
the buildings.
B The weights of four dogs Jason is raising are 60 lb,
70 lb, 68 lb, and 80 lb. Find x, the sum of the weights of
the four dogs.
Answer choices continued on the next slide
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Chapter 26
Standardized Test Preparation
3. Which of the following story problems can be solved
by the equation below?
(60  70  68  80  x)  5  70
Answer choices continued from previous slide
C Kayla’s first four handmade bracelets sold for $60,
$70, $68, and $80. Find x, the amount for which Kayla
needs to sell her fifth bracelet to have an average
selling price of $70.
D The times it took Taylor to complete each of four 100
m practice swims were 60 s, 70 s, 68 s, and 80 s. Find
x, the average time it took Taylor to complete his
practice swims.
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Chapter 26
Standardized Test Preparation
3. Which of the following story problems can be solved
by the equation below?
(60  70  68  80  x)  5  70
A The heights of four buildings in South Braintree are
60 ft, 70 ft, 68 ft, and 80 ft. Find x, the average height of
the buildings.
B The weights of four dogs Jason is raising are 60 lb,
70 lb, 68 lb, and 80 lb. Find x, the sum of the weights of
the four dogs.
Answer choices continued on the next slide
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Chapter 26
Standardized Test Preparation
3. Which of the following story problems can be solved
by the equation below?
(60  70  68  80  x)  5  70
Answer choices continued from previous slide
C Kayla’s first four handmade bracelets sold for $60,
$70, $68, and $80. Find x, the amount for which Kayla
needs to sell her fifth bracelet to have an average
selling price of $70.
D The times it took Taylor to complete each of four 100
m practice swims were 60 s, 70 s, 68 s, and 80 s. Find
x, the average time it took Taylor to complete his
practice swims.
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Chapter 26
Section 1 Animal Reproduction
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Chapter 26
Section 3 Growth and Development
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Chapter 26
Section 3 Growth and Development
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Chapter 26
Standardized Test Preparation
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