Heredity and Growth In this lesson, you will Learn About… How traits are passed from parents to children. How a baby develops inside its mother’s body. The stages in the life cycle.

Bell Work Make a List of different traits that you think you got from your parents.

Standards 1: The student will comprehend concepts related to health promotion to enhance health.

Indicators/ Essential Question Prove that traits are passed down from your parents? Use evidence.

Relevance Predict how genes and traits from parents affect a baby’s life cycle.

Heredity and Growth The Vocabulary terms in this lesson are: Heredity Chromosomes Genes Egg cell Sperm cell Fertilization Uterus Umbilical cord

Heredity Heredity is the process by which parents pass traits to their children. Traits may include eye color, hair color, and body build. Children may inherit musical or athletic ability or diseases from parents.

Heredity (cont’d.) Parents pass down their traits through their chromosomes.chromosomes Each pair of chromosomes in your body contains one chromosome each from your mother and father.

Heredity (cont’d.) Each chromosome is divided into small sections called genes.genes Each gene is related to a particular trait such as height or eye color. Each person has a unique arrangement of genes. Only identical twins share 100 percent of their genes.

Combining Chromosomes Almost every cell in your body contains 46 chromosomes – 23 from each parent. Only reproductive cells do not have 46 chromosomes. Egg cellsEgg cells and sperm cells are reproductive cells and have 23 chromosomes each.sperm cells During fertilization, an egg cell and a sperm cell combine to produce a cell with 46 chromosomes.fertilization

X and Y Chromosomes Special chromosomes in sperm cells determine whether a fertilized cell will develop into a male or female. Each sperm cell contains either an X chromosome or a Y chromosome.

X and Y Chromosomes (cont’d.) Every egg cell contains only an X chromosome. If an X-carrying sperm combines with the egg cell, it will produce a girl. If a Y-carrying sperm combines with the egg cell, it will produce a boy.

Development Before Birth A fertilized egg cell develops inside the mother’s uterus.uterus The baby gets its nourishment through the umbilical cord.umbilical cord Blood from the mother carries food and oxygen through the cord to the baby. The cord also carries wastes away.

Development Before Birth (cont’d.) TimeSizeFeaturesDevelopment Fertilizationmicroscopicsingle cellundeveloped 3 months after fertilization about 3 inches long; weighs about 1 ounce 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 Life Cycle During your life, you will go through many stages of growth and development. These stages are called the life cycle. The life cycle begins with birth and continues through childhood, adolescence, and adulthood.

The Life Cycle (cont’d.) There are six stages of the life cycle: 1.Infancy 2.Childhood 3.Adolescence 4.Early adulthood 5.Middle adulthood 6.Late adulthood

Reviewing Terms and Facts 1.________ is the process by which parents pass traits to their children. Heredity

Reviewing Terms and Facts 2.In what part of the mother’s body does a baby develop during pregnancy? A baby develops in the mother’s uterus during pregnancy.

Reviewing Terms and Facts 3.Which cells in the human body do not have 46 chromosomes? Egg cells and sperm cells do not have 46 chromosomes; they have 23 chromosomes.

Chapter Review

Reviewing Terms and Facts 1.A ___________ is a group of organs that perform a body function. body system

2._____________ is the the force of blood pushing against the walls of the blood vessels. Blood pressure Reviewing Terms and Facts

3.________ are cells that carry electrical messages. Neurons Reviewing Terms and Facts

4.________ is how you act in situations that occur in your life. Behavior Reviewing Terms and Facts

5.An ________ is the reproductive cell in the female body. egg cell Reviewing Terms and Facts

6.Think about the different body systems. Which do you seem to have control over? Which seem to work by themselves? Share your answer with the class. Thinking Critically

7.Think about the role of the heart within the circulatory system. Identify actions or behaviors that you can engage in to protect the health of this vital organ. The heart acts as the pump for the circulatory system. Thinking Critically

8.Why does lifting heavy objects improperly present a risk of injury to the nervous system? Lifting heavy objects improperly could put a strain on the spinal cord and injure it. Thinking Critically

9.How do you think you will develop socially during adolescence? Some of the signs of social development during adolescence include a sense of a separate identity and the growing importance of friends. Thinking Critically

10.Explain what determines whether a child will be male or female. Every egg cell contains only an X chromosome. If an X-carrying sperm combines with the egg cell, it will produce a female. If a Y-carrying sperm cell combines with the egg cell, it will produce a male. Thinking Critically

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

Vocabulary Review Chromosomes are pairs of tiny, threadlike pieces of matter that carry the codes for inherited traits.

Vocabulary Review Genes are the basic units of heredity.

Vocabulary Review An egg cell is the reproductive cell in the female body.

Vocabulary Review A sperm cell is the reproductive cell in the male body.

Vocabulary Review The joining together of an egg cell and a sperm cell is called fertilization.

Vocabulary Review The uterus is a pear-shaped organ that expands as a baby grows.

Vocabulary Review The umbilical cord is a tube that connects the lining of the uterus to the unborn baby.