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Bacteria are the second smallest living things on Earth with only viruses being smaller. They are very small organisms which usually consist of only a single cell. They do not have chlorophyll that is found in plants which allow for the production of food. If one million of the tiny bacteria were laid end-to-end, they would only measure about two inches. The word bacteria is plural, and bacterium describes a single organism.

An amateur scientist named Anton van Leeuwenhoek was the first person to see bacteria and other tiny organisms under a microscope. Though tiny, they are found everywhere. Bacteria is found in the air, soil, and water, as well as inside and outside of the human body. They reproduce quickly if the conditions are right. Millions of the tiny organisms can form in a space as small as a drop of water.

[A] Bacteria are usually placed in three categories depending on their shapes. The can be described a spherical (like a football), rod-like, or shaped like a spiral or corkscrew. There are also some bacteria shaped like a comma used in writing, but much smaller. There is helpful bacteria and harmful bacteria. Some can improve human life, but others can cause diseases. In addition, there are many more that simply have no effect on humans.

[B] The helpful bacteria assist with the digestion of foods in several kinds of animals including cows, deer, sheep and others. The bacteria help break down some of the foods the animals eat. In humans, a bacteria called E. coli also occur in the digestive system breaking down many kinds of foods. It is responsible for producing vitamin K and certain b vitamins.

[C] Other bacteria are decomposers in the food chain, which attack dead animals and break them down. They are then used as nutrients by plants. Bacteria is also part of the production of many foods eaten by people. Bacteria causes milk to become sour which helps in the production of buttermilk, cottage cheese, and yogurt. Bacteria is involved in the production of sauerkraut and vinegar too.

[D] It can directly attack the tissues in a plant or animal. Sometimes fruits or vegetables become discolored due the attack by bacteria. Bacteria can also cause harm organisms by releasing chemicals that are poisonous to plants and animals. One type is responsible for a disease known as tetanus, which can paralyze the muscles of a person. The condition when this occurs is called lockjaw. Finally, the worst type of food poisoning is caused by a bacterium releasing a toxin. This type of food poisoning is called botulism.

There are also harmful bacteria living on the skin, but are not dangerous unless they enter the bloodstream through a cut in the skin. If E. coli, though helpful with digestion, enters the bloodstream it can cause cramping, diarrhea and maybe even death.

Methods to destroy bacteria include freezing and drying during food preservation or through pasteurization, which is the process of heating food to a specific temperature for a period of time. This is how bacteria are killed during the processing of milk.

In summary, bacteria are everywhere and can be harmful or helpful to humans and other organisms.

Which of the following is used for grouping bacteria?

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Antioxidants are substances - artificial or natural - that prevent and slow cell and tissue damage by attacking free radicals, which are molecules that have an unpaired electron. Free radicals are natural byproducts of our metabolism and are also generated in response to environmental stressors, such as exposure to pollution, X-rays or cigarette smoke. In high quantities, free radicals can cause oxidative stress, which is when the body has too many free radicals that start to destroy DNA, fatty tissue and proteins. [A]

Unlike free radicals, antioxidants have extra electrons. This means that they can pass their surplus electrons to free radicals, stabilizing the free radicals so they can no longer damage the body's cells and tissues. In doing so, antioxidants ward off or slow oxidative stress, preventing serious illnesses. Oxidative stress has been linked with illnesses such as cancer, heart disease and some neurodegenerative diseases, including Alzheimer's and Parkinson's disease. The best way to increase antioxidants in the body and maintain a healthy balance of free radicals is to incorporate antioxidant-rich foods into your diet. [B]

The term “antioxidant” is often used to describe different foods, but it more accurately describes chemical property. Any substance that can strip free radicals of their damaging properties is considered an antioxidant. Researchers have discovered hundreds of substances that fit the antioxidant description, and there are perhaps thousands more. Vitamin C and vitamin E are two of the most common antioxidants found in food. In addition to fighting free radicals, vitamin C supports the immune system and helps repair bones, teeth and cartilage. Vitamin E is a powerful tool in maintaining eye health, producing hormones that regulate blood pressure and repairing muscles after exercise. Carotenoids- a class of compounds found in fruits and vegetables that are red, orange and yellow - are also well-known antioxidants.

Antioxidant carotenoids include beta-carotene, lycopene, lutein and zeaxanthin. However, taking high doses of some carotenoid supplements, such as beta-carotene. Can increase health risks, such as an increased chance of lung cancer in smokers. [C]

Antioxidants are most often in fruits, vegetables and legumes, although they can be found in almost every food group. Fruits contains essential nutrients such as potassium, fibre and folate - nutrients that help maintain blood pressure, lower cholesterol and repair body tissues. Blueberries, cranberries, apples, strawberries and more are all filled with antioxidants. Dried fruits - although often high in processed sugars - have a higher antioxidant ratio than fresh fruits, since they lose mass from water. They act as quick antioxidant fuel due to their high concentration of antioxidants. Carotenoids are found in red, orange or yellow vegetables. Many green vegetables such as kale, broccoli and spinach are excellent sources of antioxidants, namely quercetin and lutein. [D]

The word "fit" is closest in meaning to________.

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Antioxidants are substances - artificial or natural - that prevent and slow cell and tissue damage by attacking free radicals, which are molecules that have an unpaired electron. Free radicals are natural byproducts of our metabolism and are also generated in response to environmental stressors, such as exposure to pollution, X-rays or cigarette smoke. In high quantities, free radicals can cause oxidative stress, which is when the body has too many free radicals that start to destroy DNA, fatty tissue and proteins. [A]

Unlike free radicals, antioxidants have extra electrons. This means that they can pass their surplus electrons to free radicals, stabilizing the free radicals so they can no longer damage the body's cells and tissues. In doing so, antioxidants ward off or slow oxidative stress, preventing serious illnesses. Oxidative stress has been linked with illnesses such as cancer, heart disease and some neurodegenerative diseases, including Alzheimer's and Parkinson's disease. The best way to increase antioxidants in the body and maintain a healthy balance of free radicals is to incorporate antioxidant-rich foods into your diet. [B]

The term “antioxidant” is often used to describe different foods, but it more accurately describes chemical property. Any substance that can strip free radicals of their damaging properties is considered an antioxidant. Researchers have discovered hundreds of substances that fit the antioxidant description, and there are perhaps thousands more. Vitamin C and vitamin E are two of the most common antioxidants found in food. In addition to fighting free radicals, vitamin C supports the immune system and helps repair bones, teeth and cartilage. Vitamin E is a powerful tool in maintaining eye health, producing hormones that regulate blood pressure and repairing muscles after exercise. Carotenoids- a class of compounds found in fruits and vegetables that are red, orange and yellow - are also well-known antioxidants.

Antioxidant carotenoids include beta-carotene, lycopene, lutein and zeaxanthin. However, taking high doses of some carotenoid supplements, such as beta-carotene. Can increase health risks, such as an increased chance of lung cancer in smokers. [C]

Antioxidants are most often in fruits, vegetables and legumes, although they can be found in almost every food group. Fruits contains essential nutrients such as potassium, fibre and folate - nutrients that help maintain blood pressure, lower cholesterol and repair body tissues. Blueberries, cranberries, apples, strawberries and more are all filled with antioxidants. Dried fruits - although often high in processed sugars - have a higher antioxidant ratio than fresh fruits, since they lose mass from water. They act as quick antioxidant fuel due to their high concentration of antioxidants. Carotenoids are found in red, orange or yellow vegetables. Many green vegetables such as kale, broccoli and spinach are excellent sources of antioxidants, namely quercetin and lutein. [D]

According to the passage, which antioxidant is especially good for people who do a lot of physically demanding activities?

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Antioxidants are substances - artificial or natural - that prevent and slow cell and tissue damage by attacking free radicals, which are molecules that have an unpaired electron. Free radicals are natural byproducts of our metabolism and are also generated in response to environmental stressors, such as exposure to pollution, X-rays or cigarette smoke. In high quantities, free radicals can cause oxidative stress, which is when the body has too many free radicals that start to destroy DNA, fatty tissue and proteins. [A]

Unlike free radicals, antioxidants have extra electrons. This means that they can pass their surplus electrons to free radicals, stabilizing the free radicals so they can no longer damage the body's cells and tissues. In doing so, antioxidants ward off or slow oxidative stress, preventing serious illnesses. Oxidative stress has been linked with illnesses such as cancer, heart disease and some neurodegenerative diseases, including Alzheimer's and Parkinson's disease. The best way to increase antioxidants in the body and maintain a healthy balance of free radicals is to incorporate antioxidant-rich foods into your diet. [B]

The term “antioxidant” is often used to describe different foods, but it more accurately describes chemical property. Any substance that can strip free radicals of their damaging properties is considered an antioxidant. Researchers have discovered hundreds of substances that fit the antioxidant description, and there are perhaps thousands more. Vitamin C and vitamin E are two of the most common antioxidants found in food. In addition to fighting free radicals, vitamin C supports the immune system and helps repair bones, teeth and cartilage. Vitamin E is a powerful tool in maintaining eye health, producing hormones that regulate blood pressure and repairing muscles after exercise. Carotenoids- a class of compounds found in fruits and vegetables that are red, orange and yellow - are also well-known antioxidants.

Antioxidant carotenoids include beta-carotene, lycopene, lutein and zeaxanthin. However, taking high doses of some carotenoid supplements, such as beta-carotene. Can increase health risks, such as an increased chance of lung cancer in smokers. [C]

Antioxidants are most often in fruits, vegetables and legumes, although they can be found in almost every food group. Fruits contains essential nutrients such as potassium, fibre and folate - nutrients that help maintain blood pressure, lower cholesterol and repair body tissues. Blueberries, cranberries, apples, strawberries and more are all filled with antioxidants. Dried fruits - although often high in processed sugars - have a higher antioxidant ratio than fresh fruits, since they lose mass from water. They act as quick antioxidant fuel due to their high concentration of antioxidants. Carotenoids are found in red, orange or yellow vegetables. Many green vegetables such as kale, broccoli and spinach are excellent sources of antioxidants, namely quercetin and lutein. [D]

Which serve as the best title for the last paragraph?

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Antioxidants are substances - artificial or natural - that prevent and slow cell and tissue damage by attacking free radicals, which are molecules that have an unpaired electron. Free radicals are natural byproducts of our metabolism and are also generated in response to environmental stressors, such as exposure to pollution, X-rays or cigarette smoke. In high quantities, free radicals can cause oxidative stress, which is when the body has too many free radicals that start to destroy DNA, fatty tissue and proteins. [A]

Unlike free radicals, antioxidants have extra electrons. This means that they can pass their surplus electrons to free radicals, stabilizing the free radicals so they can no longer damage the body's cells and tissues. In doing so, antioxidants ward off or slow oxidative stress, preventing serious illnesses. Oxidative stress has been linked with illnesses such as cancer, heart disease and some neurodegenerative diseases, including Alzheimer's and Parkinson's disease. The best way to increase antioxidants in the body and maintain a healthy balance of free radicals is to incorporate antioxidant-rich foods into your diet. [B]

The term “antioxidant” is often used to describe different foods, but it more accurately describes chemical property. Any substance that can strip free radicals of their damaging properties is considered an antioxidant. Researchers have discovered hundreds of substances that fit the antioxidant description, and there are perhaps thousands more. Vitamin C and vitamin E are two of the most common antioxidants found in food. In addition to fighting free radicals, vitamin C supports the immune system and helps repair bones, teeth and cartilage. Vitamin E is a powerful tool in maintaining eye health, producing hormones that regulate blood pressure and repairing muscles after exercise. Carotenoids- a class of compounds found in fruits and vegetables that are red, orange and yellow - are also well-known antioxidants.

Antioxidant carotenoids include beta-carotene, lycopene, lutein and zeaxanthin. However, taking high doses of some carotenoid supplements, such as beta-carotene. Can increase health risks, such as an increased chance of lung cancer in smokers. [C]

Antioxidants are most often in fruits, vegetables and legumes, although they can be found in almost every food group. Fruits contains essential nutrients such as potassium, fibre and folate - nutrients that help maintain blood pressure, lower cholesterol and repair body tissues. Blueberries, cranberries, apples, strawberries and more are all filled with antioxidants. Dried fruits - although often high in processed sugars - have a higher antioxidant ratio than fresh fruits, since they lose mass from water. They act as quick antioxidant fuel due to their high concentration of antioxidants. Carotenoids are found in red, orange or yellow vegetables. Many green vegetables such as kale, broccoli and spinach are excellent sources of antioxidants, namely quercetin and lutein. [D]

The sentence "This is where antioxidants can save the day." can best fit which of the numbered spaces in the passage.

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Antioxidants are substances - artificial or natural - that prevent and slow cell and tissue damage by attacking free radicals, which are molecules that have an unpaired electron. Free radicals are natural byproducts of our metabolism and are also generated in response to environmental stressors, such as exposure to pollution, X-rays or cigarette smoke. In high quantities, free radicals can cause oxidative stress, which is when the body has too many free radicals that start to destroy DNA, fatty tissue and proteins. [A]

Unlike free radicals, antioxidants have extra electrons. This means that they can pass their surplus electrons to free radicals, stabilizing the free radicals so they can no longer damage the body's cells and tissues. In doing so, antioxidants ward off or slow oxidative stress, preventing serious illnesses. Oxidative stress has been linked with illnesses such as cancer, heart disease and some neurodegenerative diseases, including Alzheimer's and Parkinson's disease. The best way to increase antioxidants in the body and maintain a healthy balance of free radicals is to incorporate antioxidant-rich foods into your diet. [B]

The term “antioxidant” is often used to describe different foods, but it more accurately describes chemical property. Any substance that can strip free radicals of their damaging properties is considered an antioxidant. Researchers have discovered hundreds of substances that fit the antioxidant description, and there are perhaps thousands more. Vitamin C and vitamin E are two of the most common antioxidants found in food. In addition to fighting free radicals, vitamin C supports the immune system and helps repair bones, teeth and cartilage. Vitamin E is a powerful tool in maintaining eye health, producing hormones that regulate blood pressure and repairing muscles after exercise. Carotenoids- a class of compounds found in fruits and vegetables that are red, orange and yellow - are also well-known antioxidants.

Antioxidant carotenoids include beta-carotene, lycopene, lutein and zeaxanthin. However, taking high doses of some carotenoid supplements, such as beta-carotene. Can increase health risks, such as an increased chance of lung cancer in smokers. [C]

Antioxidants are most often in fruits, vegetables and legumes, although they can be found in almost every food group. Fruits contains essential nutrients such as potassium, fibre and folate - nutrients that help maintain blood pressure, lower cholesterol and repair body tissues. Blueberries, cranberries, apples, strawberries and more are all filled with antioxidants. Dried fruits - although often high in processed sugars - have a higher antioxidant ratio than fresh fruits, since they lose mass from water. They act as quick antioxidant fuel due to their high concentration of antioxidants. Carotenoids are found in red, orange or yellow vegetables. Many green vegetables such as kale, broccoli and spinach are excellent sources of antioxidants, namely quercetin and lutein. [D]

Who do you think the article is most likely written for?

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Antioxidants are substances - artificial or natural - that prevent and slow cell and tissue damage by attacking free radicals, which are molecules that have an unpaired electron. Free radicals are natural byproducts of our metabolism and are also generated in response to environmental stressors, such as exposure to pollution, X-rays or cigarette smoke. In high quantities, free radicals can cause oxidative stress, which is when the body has too many free radicals that start to destroy DNA, fatty tissue and proteins. [A]

Unlike free radicals, antioxidants have extra electrons. This means that they can pass their surplus electrons to free radicals, stabilizing the free radicals so they can no longer damage the body's cells and tissues. In doing so, antioxidants ward off or slow oxidative stress, preventing serious illnesses. Oxidative stress has been linked with illnesses such as cancer, heart disease and some neurodegenerative diseases, including Alzheimer's and Parkinson's disease. The best way to increase antioxidants in the body and maintain a healthy balance of free radicals is to incorporate antioxidant-rich foods into your diet. [B]

The term “antioxidant” is often used to describe different foods, but it more accurately describes chemical property. Any substance that can strip free radicals of their damaging properties is considered an antioxidant. Researchers have discovered hundreds of substances that fit the antioxidant description, and there are perhaps thousands more. Vitamin C and vitamin E are two of the most common antioxidants found in food. In addition to fighting free radicals, vitamin C supports the immune system and helps repair bones, teeth and cartilage. Vitamin E is a powerful tool in maintaining eye health, producing hormones that regulate blood pressure and repairing muscles after exercise. Carotenoids- a class of compounds found in fruits and vegetables that are red, orange and yellow - are also well-known antioxidants.

Antioxidant carotenoids include beta-carotene, lycopene, lutein and zeaxanthin. However, taking high doses of some carotenoid supplements, such as beta-carotene. Can increase health risks, such as an increased chance of lung cancer in smokers. [C]

Antioxidants are most often in fruits, vegetables and legumes, although they can be found in almost every food group. Fruits contains essential nutrients such as potassium, fibre and folate - nutrients that help maintain blood pressure, lower cholesterol and repair body tissues. Blueberries, cranberries, apples, strawberries and more are all filled with antioxidants. Dried fruits - although often high in processed sugars - have a higher antioxidant ratio than fresh fruits, since they lose mass from water. They act as quick antioxidant fuel due to their high concentration of antioxidants. Carotenoids are found in red, orange or yellow vegetables. Many green vegetables such as kale, broccoli and spinach are excellent sources of antioxidants, namely quercetin and lutein. [D]

According to the passage, which of the following is true about free radicals?

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Antioxidants are substances - artificial or natural - that prevent and slow cell and tissue damage by attacking free radicals, which are molecules that have an unpaired electron. Free radicals are natural byproducts of our metabolism and are also generated in response to environmental stressors, such as exposure to pollution, X-rays or cigarette smoke. In high quantities, free radicals can cause oxidative stress, which is when the body has too many free radicals that start to destroy DNA, fatty tissue and proteins. [A]

Unlike free radicals, antioxidants have extra electrons. This means that they can pass their surplus electrons to free radicals, stabilizing the free radicals so they can no longer damage the body's cells and tissues. In doing so, antioxidants ward off or slow oxidative stress, preventing serious illnesses. Oxidative stress has been linked with illnesses such as cancer, heart disease and some neurodegenerative diseases, including Alzheimer's and Parkinson's disease. The best way to increase antioxidants in the body and maintain a healthy balance of free radicals is to incorporate antioxidant-rich foods into your diet. [B]

The term “antioxidant” is often used to describe different foods, but it more accurately describes chemical property. Any substance that can strip free radicals of their damaging properties is considered an antioxidant. Researchers have discovered hundreds of substances that fit the antioxidant description, and there are perhaps thousands more. Vitamin C and vitamin E are two of the most common antioxidants found in food. In addition to fighting free radicals, vitamin C supports the immune system and helps repair bones, teeth and cartilage. Vitamin E is a powerful tool in maintaining eye health, producing hormones that regulate blood pressure and repairing muscles after exercise. Carotenoids- a class of compounds found in fruits and vegetables that are red, orange and yellow - are also well-known antioxidants.

Antioxidant carotenoids include beta-carotene, lycopene, lutein and zeaxanthin. However, taking high doses of some carotenoid supplements, such as beta-carotene. Can increase health risks, such as an increased chance of lung cancer in smokers. [C]

Antioxidants are most often in fruits, vegetables and legumes, although they can be found in almost every food group. Fruits contains essential nutrients such as potassium, fibre and folate - nutrients that help maintain blood pressure, lower cholesterol and repair body tissues. Blueberries, cranberries, apples, strawberries and more are all filled with antioxidants. Dried fruits - although often high in processed sugars - have a higher antioxidant ratio than fresh fruits, since they lose mass from water. They act as quick antioxidant fuel due to their high concentration of antioxidants. Carotenoids are found in red, orange or yellow vegetables. Many green vegetables such as kale, broccoli and spinach are excellent sources of antioxidants, namely quercetin and lutein. [D]

How do antioxidants protect the body?