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# 24.4: Environmental Problems and Human Health

Difficulty Level: At Grade Created by: CK-12

## Lesson 24.4: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. Most carcinogens cause cancer by producing mutations in DNA.

_____ 2. Most cancers are caused by viruses.

_____ 3. UV radiation is the leading cause of lung cancer.

_____ 4. Tumor-suppressor genes normally help control cell division.

_____ 5. More cancer deaths in adults are due to lung cancer than any other type of cancer.

_____ 6. Almost 5 million people die each year because of air pollution.

_____ 7. Oncogenes promote the division of cells with damaged DNA.

_____ 8. A low AQI value is the most hazardous.

_____ 9. Smog contains tiny particles of solids or liquids that are suspended in the air.

_____ 10. Bioterrorism is usually an accident.

_____ 11. Exposure to tobacco smoke is the leading cause of lung cancer.

_____ 12. Not smoking, or stopping smoking, can reduce your own risk of getting cancer.

## Lesson 24.4: Critical Reading

Name___________________ Class______________ Date________

Read these passages from the text and answer the questions that follow.

Carcinogens and Cancer

A carcinogen is anything that can cause cancer. Cancer is a disease in which cells divide out of control. Most carcinogens cause cancer by producing mutations in DNA.

Types of Carcinogens

There are several different types of carcinogens. They include pathogens, radiation, and chemicals. Some carcinogens occur naturally. Others are produced by human actions.

• Viruses cause about 15 percent of all human cancers. For example, the virus called hepatitis B causes liver cancer.
• UV radiation is the leading cause of skin cancer. The radioactive gas known as radon causes lung cancer.
• Tobacco smoke contains dozens of carcinogens, including nicotine and formaldehyde. Exposure to tobacco smoke is the leading cause of lung cancer.
• Some chemicals that were previously added to foods, such as certain dyes, are now known to cause cancer. Cooking foods at very high temperatures also causes carcinogens to form.

How Cancer Occurs

Mutations that lead to cancer usually occur in genes that control the cell cycle. These include tumor-suppressor genes and proto-oncogenes.

• Tumor-suppressor genes normally prevent cells with damaged DNA from dividing. Mutations in these genes prevent them from functioning normally. As a result, cells with damaged DNA are allowed to divide.
• Proto-oncogenes normally help control cell division. Mutations in these genes turn them into oncogenes. Oncogenes promote the division of cells with damaged DNA.

Cells that divide uncontrollably may form a tumor, or abnormal mass of cells. Tumors may be benign or malignant. Benign tumors remain localized and generally do not harm health. Malignant tumors are cancerous. There are no limits to their growth, so they can invade and damage neighboring tissues. Cells from malignant tumors may also break away from the tumor and enter the bloodstream. They are carried to other parts of the body, where new tumors may form.

Questions

1. What is a carcinogen? What is cancer?

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2. Describe two carcinogens.

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3. What is a tumor-suppressor gene?

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4. What is a proto-oncogene?

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5. Discuss how a malignant tumor can cause cancer.

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## Lesson 24.4: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

1. Which statement is true concerning cancer?
1. Most carcinogens cause cancer by producing mutations in DNA.
2. Cancer is a disease in which cells divide out of control.
3. A carcinogen is anything that can cause cancer.
4. all of the above
2. Carcinogens include
1. viruses, which cause about 50 percent of all human cancers.
2. UV radiation, which is the leading cause of lung cancer.
3. exposure to tobacco smoke, which is the leading cause of skin cancer.
4. none of the above.
3. The most common deadly cancer in the United States is
1. skin cancer.
2. lung cancer.
3. breast cancer.
4. prostate cancer.
4. Tumor-suppressor genes
1. help cells with damaged DNA to divide.
2. normally help control cell division.
3. prevent cells with damaged DNA from dividing.
4. normally help stop cell division.
5. Warning signs of cancer include
1. a lump in the breast or elsewhere.
2. an obvious changes in a wart or mole.
3. an unusual bleeding or discharge.
4. all of the above.
6. The Air Quality Index
1. measures levels of ground-level ozone and particulates.
2. is one of the main components of smog.
3. is harmful to people with certain health problems, such as asthma.
4. affects almost 5 million people each year.
7. Bioterrorism
1. contains dozens of carcinogens, and is the leading cause of lung cancer.
2. is the intentional release of disease causing viruses, bacteria, or other toxins.
3. includes pollutants in the outdoor air.
4. includes anything that causes cancer.
8. Air pollution
1. can make asthma and other diseases more severe.
2. can cause skin cancer.
3. is the leading cause of lung cancer.
4. all of the above

## Lesson 24.4: Vocabulary I

Name___________________ Class______________ Date________

Match the vocabulary word with the proper definition.

Definitions

_____ 1. kills almost 5 million people die each year

_____ 2. when inhaled, replaces oxygen in the blood and quickly leads to death

_____ 3. anything that can cause cancer

_____ 4. normally help control cell division

_____ 5. contains dozens of carcinogens

_____ 6. an assessment of the pollutants in the outdoor air based on their human health effects

_____ 7. the leading cause of skin cancer

_____ 8. the intentional release or spread of agents of disease

_____ 9. normally prevent cells with damaged DNA from dividing

_____ 10. one of the main components of smog

_____ 11. cause about 15 percent of all human cancers

_____ 12. a disease in which cells divide out of control

Terms

a. Air Quality Index (AQI)

b. air pollution

c. bioterrorism

d. cancer

e. carbon monoxide

f. carcinogen

g. ozone

h. proto-oncogenes

i. tobacco smoke

j. tumor-suppressor genes

l. viruses

## Lesson 24.4: Vocabulary II

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

1. A carcinogen is anything that can cause ____________.

2. There are no limits to the ____________ of malignant tumors, so they can invade and damage neighboring tissues.

3. Most carcinogens cause cancer by producing ____________ in DNA.

4. Exposure to ____________ smoke causes lung cancer.

5. UV radiation is the leading cause of ____________ cancer.

6. Air pollution harms the ____________ and circulatory systems.

7. Tumor-suppressor ____________ normally prevent cells with damaged DNA from dividing.

8. Proto-oncogenes normally help control cell ____________.

9. ____________ is the intentional release or spread of agents of disease.

10. Indoor air may contain harmful substances such as mold, ____________, and radon.

11. ____________ cause about 15 percent of all human cancers.

12. Cells that divide uncontrollably may form a ____________.

## Lesson 24.4: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

Identify two causes of air pollution and its effects on human health.

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