1. Growth and Development
Chapter 8
Growth and Development
Lesson 3
Heredity and the Life Cycle
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2. Tiny strands of matter that carry the codes for inherited traits
chromosomes
genes
fetus
prenatal care
Tiny strands of matter that carry the codes for inherited traits
The basic units of heredity
What the developing unborn baby is known as from the eighth week until birth
Click to reveal the definitions.
Special care to ensure that an expecting mother and the baby remain healthy

3. In this lesson, you will learn to
explain how inherited traits are passed along.
identify changes to the developing baby.
recognize stages in the life-cycle.

4. The Developing Baby Analyzing a Graphic
After 3 months
After 6 months
After 9 months
The Developing Baby
Analyzing a Graphic
Using this diagram as a guide, describe the stages of development before birth.

5. Hair color and body build are examples of inherited traits.
Heredity
Heredity is the process by which parents pass certain traits to their children.
Hair color and body build are examples of inherited traits.
Children may also inherit talents and abilities. The likelihood of developing certain diseases and health problems is also passed along.

6. Traits are passed along by chromosomes.
Heredity
Traits are passed along by chromosomes.
chromosomes Tiny strands of matter that carry the codes for inherited traits
Chromosomes are made up of genes.
Chromosomes are arranged in pairs in your body’s cells. One chromosome comes from your father, the other from your mother.
genes The basic units of heredity

7. Chromosomes and Fertilization
Among each sperm’s 23 chromosomes, one alone determines the gender of the fertilized egg cell.
An egg caries only an X chromosome. Sperm carry either an X or Y chromosome.
If a sperm carries an X chromosome, a female will result. If a sperm carries a Y chromosome, a male will result.
Every type of cell in the human body except one contains 46 chromosomes. That one exception is the reproductive cell. The newly fertilized egg has 46 chromosomes.

8. Development Before Birth
The newly fertilized egg travels down the fallopian tube to the uterus.
The egg attaches itself to the wall of the uterus.
The egg begins to be divided millions of times.
The tissues, organs, and body systems are eventually formed.

9. The Developing Baby Time Size Features Development fertilization
microscopic
arms, legs, fingers, toes, eyes, ears
heart is beating; nervous system is forming; cannot survive outside uterus
6 months after fertilization
about 14 inches long; weighs about 2 pounds
hair, eyebrows, fingernails, toenails
can move and kick; sucks thumb; can hear sounds; might survive outside uterus
9 months after fertilization
18–20 inches long; weighs 7–9 pounds
smooth skin, fully developed organs
eyes open and close; fingers can grasp; body organs and systems can now work on their own; ready for birth

10. The Developing Baby
In the uterus, the fetus receives oxygen and nutrients through a tube called the umbilical cord.
fetus What the developing unborn baby is known as from the eighth week until birth

11. Throughout pregnancy, an expectant mother needs prenatal care.
The Developing Baby
Throughout pregnancy, an expectant mother needs prenatal care.
prenatal care Special care to ensure that the expectant mother and the baby remain healthy
Pregnancy is a joyful event, but is also means added responsibility. New parents often don’t get a lot of sleep and may experience added stress or other emotional changes.
The mother-to-be must avoid tobacco, alcohol, and other drugs not prescribed by the doctor.
Prenatal care includes eating healthy foods, getting enough rest, and seeing the doctor regularly.

12. The life cycle is divided into six major stages.
Infancy
Childhood
Adolescence
Early Adulthood
Middle Adulthood
Late Adulthood
Infancy – Age 1
Physically, babies grow fast. Babies also grow mentally/emotionally.
Infants need loving physical car and attention.
Childhood – Ages 1 to 11
During this time, children are busy absorbing information. Encouragement at this stage builds self-esteem.
Adolescence – Ages 12 to 18
This is a time of transition.
Skills such as decision making, goal setting, and good communication help prepare adolescents for adulthood
Early Adulthood – Ages 19 to 30
Many young adults are busy pursuing and education or training for a career..
Some young adults choose to get married and start a family.
Middle Adulthood – Ages 30 to 60
Many at this stage look at ways to contribute to the community.
People at this stage begin planning for the final stage
Late Adulthood – 60+
People at this stage are thinking about retirement,
Those who maintain good health will be able to stay active through this stage.
Age 1
Ages 1–11
Ages 12–18
Ages 19–30
Ages 30–60
Ages 60+

13. What I Learned Vocabulary Define chromosomes. Lesson 3 Review
Chromosomes are tiny strands of matter that carry the codes for inherited traits.

14. Lesson 3 Review
What I Learned
Recall How many chromosomes are there in most cells of the human body? What is the one exception?
There are 46 chromosomes in all body cells except for the reproductive cells, which have 23.

15. Lesson 3 Review
What I Learned
Identify Name two developments that may take place during early adulthood.
Sample answer: advancing one's education, planning or beginning a career, getting married, starting a family

16. Lesson 3 Review
Thinking Critically
Explain What determines whether a baby will be male or female?
The presence of an X or Y chromosome in the sperm cells determines this. An X chromosome means that a female will result, while a Y chromosome means that a male will result.

17. Lesson 3 Review
Thinking Critically
Apply Yvonne hopes to become a lawyer when she reaches adulthood. What skills can she develop now during her teens to help her achieve her career goals?
Sample answers: learning and practicing communication skills, achieving good grades

18. Growth and Development
End of
Chapter 8
Growth and Development
Lesson 3
Heredity and the Life Cycle
Click for:
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>> Chapter 8 Assessment