1. Chapter 12 Growing and Changing Lesson 5
Heredity and Human Development
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2. Threadlike structures that carry genes
chromosomes
Threadlike structures that carry genes
genes
The basic units of heredity
Click to reveal the definitions.
cell
The basic unit of life

3. A group of similar cells that do a particular job
tissue
A group of similar cells that do a particular job
A body part made up of different tissues joined to perform a particular function
organ
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body system
A group of organs that work together to carry out related tasks

4. The developing organism from the end of the eighth week until birth
The developing organism from two weeks until the end of the eighth week of development
embryo
The developing organism from the end of the eighth week until birth
fetus
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5. In this lesson, you will learn to
explain how humans inherit certain characteristics.
identify the basic unit of life.
describe how a fetus develops.
identify ways an expectant mother can care for her developing fetus.

6. Levels of Body Structure
Cells
Analyzing a Graphic
Using the diagram shown here, create a concept map about the different levels of body structure. As you read the lesson, fill in the concept map.

7. Genes carry the codes for inherited traits.
Heredity
When a sperm and egg unite, the newly fertilized egg has a complete set of chromosomes.
chromosomes Threadlike structures that carry genes
Genes carry the codes for inherited traits.
genes The basic units of heredity

8. Heredity

9. Fertilization and Human Development
How does a single cell become a person made of many cells?
cell The basic unit of life
Soon after fertilization, the fertilized egg begins to divide and multiply.

10. Fertilization and Human Development
Groups of cells make up tissues and tissues then make up organs.
tissue A group of similar cells that do a particular job
organ A body part made up of different tissues joined to perform a particular function

11. Fertilization and Human Development
Eventually, an entire body system is formed.
body system A group of organs that work together to carry out related tasks

12. Development of the Fetus
A fertilized egg is called a zygote.
The zygote divides to form 2 cells about 24 hours after fertilization.
After one week, the zygote attaches to the lining of the uterus.
After another week, the zygote is called an embryo.
Each time one of an embryo’s cells divides, it produces two cells. The number of cells continues to multiply as the embryo develops.
embryo The developing organism from two weeks until the eighth week of development

13. Fertilization and Human Development
After the eighth week, the human embryo is called a fetus.
fetus The developing organism form the end of the eighth week until birth.
The fetus gets nutrients and oxygen from its mother through the umbilical cord. This is a tube that attaches to the abdomen of the fetus. The umbilical cord is cut at birth.
Birth takes place about nine months after fertilization.

14. Positive Health Behaviors for Expectant Mothers
Care During Pregnancy
Positive Health Behaviors for Expectant Mothers
Eat healthful foods
Have regular checkups
Beware of infections
Don’t use tobacco
Don’t drink alcohol
Don’t take unnecessary
drugs
An expectant mother can do many things to create a healthy environment for her growing fetus. Since the fetus is inside the mother’s body, all of the mother’s health choices can also affect its health.
Eat healthful foods:
Because the fetus gets its nourishment directly from the mother, eating healthful foods will benefit the health of the mother and the fetus.
Have regular checkups:
A female should see a doctor as soon as she suspects that she is pregnant.
A pregnant female should take prenatal vitamins as recommended by her doctor.
Beware of infections:
Some diseases are very dangerous to the fetus. Rubella (German measles) and some sexually transmitted diseases can cause serious problems. A vaccine can protect against rubella.
Don’t use tobacco:
Smoking or chewing tobacco can harm a developing fetus.
A pregnant female should avoid being around smokers.
Don’t drink alcohol:
Any alcohol a pregnant female drinks goes into the fetus’s body.
Fetal alcohol syndrome (FAS) can effect the size a baby. Other possible effects include brain damage, mental retardation, severe emotional problems, learning disabilities, memory problems, problem-solving problems, and social problems.
Don’t take any unnecessary drugs:
Even OTC medicines can be dangerous to a fetus.
A pregnant female should take medication only if absolutely necessary and only as instructed by her doctor.
Pregnant females should avoid consuming products containing caffeine.

15. What I Learned Vocabulary Define chromosomes. Lesson 5 Review
Chromosomes are threadlike structures that carry the genes. Genes are the basic units of heredity.

16. Lesson 5 Review
What I Learned
Identify List four levels of body organization from most complex to most basic.
body system, organ, tissue, cell

17. Lesson 5 Review
What I Learned
Describe Describe the development of a human from the point of fertilization.
Answers will vary but should correctly describe fetal development as shown in Figure 12.9.

18. Lesson 5 Review
What I Learned
List What are four ways that a pregnant female can care for her developing baby?
Any four: Eat healthful foods, have regular checkups, beware of infections, don't smoke or use tobacco, don't drink alcohol, don't take any unnecessary drugs.

19. Lesson 5 Review
Thinking Critically
Apply A test of Ling’s fetus shows that its cells each have one more chromosome than normal human cells. How many chromosomes does each of her fetus cells have?
47 chromosomes

20. Lesson 5 Review
Thinking Critically
Analyze Using the information given in Figure 12.9, calculate the weight that the developing fetus gains at each three month stage. During which stage does it gain the most weight?
1 ounce, 23 ounces; pounds; the last stage

21. Chapter 12 Growing and Changing End of Lesson 5
Heredity and Human Development
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