Chapter 8Growth andDevelopment

Lesson 3Heredity and theLife Cycle

>> Main Menu

Next >>

>> Chapter 8 Assessment

Click for:

Teacher’s notes are available in the notes section of this presentation.

chromosomes

genes

fetus

prenatal care

Tiny strands of matter that carry the codes forinherited traits

The basic units of heredity

What the developing unborn baby is known as from the eighth week until birth

Special care to ensure that an expecting mother and the baby remain healthy

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.

Analyzing a Graphic

Using this diagram as a

guide, describe the stages

of development before birth.

After 3 months

After 6 months

After 9 months

The Developing Baby

Heredity

Heredity is the process by which parents pass certain traits to their children.

Hair color and body build are examples of inherited traits.

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.

genes The basic units of heredity

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.

Development Before Birth

The newly fertilized

egg travels downthe 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.

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

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

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

Prenatal care includes eating healthy foods, getting enough rest, and seeing the doctor regularly.

The Life Cycle

The life cycle is divided into six major stages.

Infancy Childhood AdolescenceEarly

AdulthoodMiddle

AdulthoodLate

Adulthood

Age 1 Ages1–11

Ages12–18

Ages19–30

Ages30–60

Ages60+

What I Learned

Vocabulary Define chromosomes.

Lesson 3 Review

What I Learned

Recall How many chromosomes are there in most cellsof the human body? What is the one exception?

Lesson 3 Review

What I Learned

Identify Name two developments that may take placeduring early adulthood.

Lesson 3 Review

Thinking Critically

Explain What determines whether a baby will be male or female?

Lesson 3 Review

Thinking Critically

Apply Yvonne hopes to become a lawyer when shereaches adulthood. What skills can she develop now during her teens to help her achieve her career goals?

Lesson 3 Review

Chapter 8Growth andDevelopment

Lesson 3Heredity and theLife Cycle

Click for:

End of

>> Main Menu

>> Chapter 8 Assessment