BIO 11A - Microorganisms

Health professionals sometimes recommend nutritional supplements that contain a variety of species of bacteria to promote good digestive health. The product label for one of these supplements is shown.

Why does this type of bacteria-filled supplement benefit human health instead of causing illness?

• Stomach acids and digestive enzymes kill the bacteria in this type of supplement, protecting the person against future infections by live organisms.

• The human digestive system contains billions of beneficial bacteria that enhance digestion and nutrient absorption, synthesize vitamins, and help limit the growth of harmful bacteria.

• These species of bacteria remove all the other species of microorganisms living in the human digestive system and ensure that no microorganisms survive to contaminate the body.

• These bacteria are able to deactivate viruses that may inhabit the human digestive system and are used to protect against further viral infections.

Large numbers of helpful bacteria normally grow and reproduce in a person's intestine. Which of the following is one way that these bacteria promote health?

• preventing pathogens from entering the body

• breaking down toxins in the digestive tract

• competing against pathogens for colonization sites

• bringing essential minerals into the body

H. pylori bacteria are known to cause stomach ulcers, which are sores in the lining of the stomach. The sores are vulnerable to damage by stomach acids. A doctor may treat ulcers by prescribing an antibiotic, such as amoxicillin, which will –

• neutralize stomach acids

• stop the formation of stomach acids

• kill the H. pylori bacteria

• cover sores in the stomach lining

Deer eat leaves and shrubs, which contain the carbohydrate cellulose. Because mammals lack the digestive enzymes needed to break down cellulose, bacteria living in the intestinal tract of a deer digest the cellulose. If the bacteria in a deer's intestinal tract were killed off, the most likely result is that the deer would –

• become malnourished and die

• digest the cellulose more slowly

• eat other plant food lower in cellulose

• die of diseases caused by other bacteria

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The bacteria that cause diphtheria live in the mouth, nose, throat, or skin of an infected person. Without treatment these bacteria can damage heart muscle, leading to heart failure. The most likely way that bacteria living in the mouth, nose, throat, or skin can damage the heart is by –

• suppressing the immune system

• clogging arteries

• breaking down the tissue for food

• secreting toxins

Lactobacillus acidophilus is a bacterium that occurs naturally in the colon. It produces enzymes that help with the final digestion of food. It produces Vitamin K, B Vitamins, and inhibits the growth of harmful bacteria. When taking an antibiotic that kills Lactobacillus acidophilus along with the targeted disease-causing bacteria, which of the following is most likely to occur?

• an increase in body vitamin levels

• a lesser risk of stomach infections

• a greater risk of intestinal infection

• a need for extra foods high in fiber

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Some Streptococcus bacteria can cause a disease called necrotizing fasciitis. Infection first produces mild redness on the skin. This leads to severe inflammation and blistering. Skin cells and underlying tissues then begin to die. People infected with this type of bacteria are most likely harmed when the bacteria –

• secrete toxins

• cause cells to multiply abnormally

• displace normal cells

• weaken the body's immune system

How can viruses be treated medically to reduce their numbers and prevent them from spreading?

• Use antibiotics to kill them and use vaccines to prevent them from spreading.

• Use vaccines to kill them and use antibiotics to prevent them from spreading.

• Prevent them from spreading using vaccines, but do not treat them with antibiotics.

• Prevent them from spreading using antibiotics, but do not treat them with vaccines.

Which of the following methods is used to reduce the spread of bacteria in the kitchen?

• Food is kept either dry or in cold environments.

• Antibiotics are used in preparation of food.

• Viruses, not bacteria, cause the spoiling of food.

• All food is treated with chemicals and pesticides.

The result of a bacterial pathogen invading your body is –

• bacteria undergoes photosynthesis

• bacteria goes into a dormant phase

• bacteria breaks down body tissue as food

• bacteria goes into the lytic cycle and divides