Bacteriaare 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 bacteriumdescribes a single organism.

An amateur scientist named Anton van Leeuwenhoekwas 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 decomposersin 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 best describes Anton van Leeuwenhoek?

According to sociologists, there are several different ways in which a person may become recognized as the leader of a social group in the United States. In the family, traditional cultural patterns confer leadership on one or both of the parents. In other cases, such as friendship groups, one or more persons may gradually emerge as leaders, although there is no formal process of selection. In larger groups, leaders are usually chosen formally through election or recruitment.

Although leaders are often thought to be people with unusual personal ability, decades of research have failed to produce consistent evidence that there is any ca gory of “natural leaders”. It seems that there is no set of personal qualities that all leaders have in common; rather, virtually any person may be recognized as a leader if the person has qualities that meet the needs of that particular group.

Furthermore, although it is commonly supposed that social groups have a single leader, research suggests that there are typically two different leadership roles that are held by different individuals. Instrumental leadership is leadership that emphasizes the completion of tasks by a social group. Group members look to instrumental leaders to “get things” done. Expressive leadership, on the other hand, is leadership that emphasizes the collectivewell-being of a social group’s member. Expressive leaders are less concerned with the overall goals of the group than with providing emotional support to group members and attempting to minimize tension and conflict among them. Group members expect expressive leaders to maintain stable relationships within the group and provide support to individual members.

Instrumental leaders are likely to have a rather secondary relationshipto other group members. They give orders and may discipline group members who inhibit attainment of the group’s goals. Expressive leaders cultivate a more personal or primary relationship to others in the group. They offer sympathy when someone experiences difficulties or is subjected to discipline, are quick to lighten a serious moment with humor, and try to resolve issues that threaten to divide the group.

As the differences in these two roles suggest, expressive leaders generally receive more personal affection from group members; instrumental leaders, if they are successful in promoting group goals, may enjoy a more distant respect.

What does the passage mainly discuss?

What is the passage mainly about?

The five senses of the body include sight, hearing, taste, smell, and touch. Human beings and most other animals use the five senses to help them live and experience the world around them. The senses also help people to learn, protect themselves, and to enjoy the differences between foods, sounds, and other experiences a person has in life. The senses also work together to give you a clear picture of the activities around you.

The first sense is sight, which depends on the eyes. People use their eyes to see the people, objects, and other items around them. Of course, the sense of sight is also helpful for reading, traveling, driving, and moving from place to place each day. Inside the eye there are special lenses that take in light to help people see things. If it is too dark, a person will have trouble seeing. The eyes can also adjust to the amount of light available. Many people, though, young and old, may also need glasses to help them see clearly. Some people may be able to see things up close, but not far away, which means they are nearsighted. If a person can see far away but not up close, they are farsighted. If a person is blind, there are special books written in braille which helps them feel the raised letters. Some blind people also have special dogs to help guide them from place to place in their home and when they go places.

The second sense, hearing, depends on the ears. There are actually three parts of the ear, the outer ear, middle ear, and the inner ear. The outer ear is the part other people can see. The outer ear catches the sound waves as they travel to the person and then sends them into the ear. The outer ear acts like a funnel collecting the different sounds a person experiences. The middle ear contains the eardrum and several bones which transfers sound from the outer ear to the inner ear. The inner ear consists of tubes and passages that takes the sound vibrations and sends themto your brain for understanding. [A]

The third sense, smell, depends on your nose. Inside the nose there is a substance that takes the fumes of an odor and then sends it to the brain. If a person gets a cold the sense of smell may not be as strong. The nose also helps clean the air a person breathes by filteringit. Inside the nose there are tiny hairs, called cilia, which act as cleaners to help keep substances in the air from entering a person's body through the nose. In addition, the nose affects the way a person speaks. If a person holds their nose while speaking, their voice will sound different. Smell also helps with the sense of taste. As a person tastes the food in their mouth, the aroma of the food enters a person's nose. [B]

The next sense, feeling, or touch, can be experienced throughout the entire body through a person's skin. Some parts of the body are more sensitive to touch than other parts. The skin has parts in it that collect information and sends it the brain. Most of a person's feeling is done by the hands. In addition, when a person has a stomach ache or feel other kinds of pain, the sense of touch is working from inside the body. [C]

The final sense, taste, comes from the taste buds on a person's tongue. As stated earlier, the sense of smell also affects the sense of taste. The tongue tastes four different flavors: salty, sweet, sour, and bitter. Many foods a person eats may be a combination of the four main flavors. The tongue can also feel whether something in a person's mouth is hot, cold, creamy, crunchy, or dry.

In summary, the five senses are sight, hearing, smell, feeling, and taste. [D]

Which of the following senses is most helpful for reading, traveling, and moving from place to place?

A “secondary relationship” mentioned in the last paragraph between a leader and the members of a group could be best characterized as.

Read the message and choose the best answer.

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?

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

How do antioxidants protect the body?