Microbes: The Invisible World

by Vocafy Đã xác minh

Anh (Mỹ) B2 12 câu hỏi Science

Discover how microbes shape food, health, and the environment, from rising bread to antibiotic resistance.

1. 1. Chọn đáp án đúng.

   What do the bacteria do that helps yogurt become sour and thick?

   When certain live bacterial cultures are added to milk under suitable conditions, yogurt forms.

   • They turn milk sugar into acid.
   • They release gas that makes the milk rise.
   • They remove fat from the milk.

   Think about what gives yogurt its sour taste.

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   • They turn milk sugar into acid.

   The bacteria produce lactic acid. This acid also changes how milk proteins interact, helping the yogurt thicken.

2. 2. Chọn đáp án đúng.

   Which group does bread mold belong to?

   A fuzzy patch of mold has appeared on a slice of bread.

   • Bacteria
   • Fungi
   • Viruses

   Mold belongs to the same broad group as mushrooms.

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   • Fungi

   Molds are fungi that often grow as networks of tiny threads. The visible patch contains many of these threads.

3. 3. Chọn đáp án đúng.

   How does this routine help reduce microbes on your hands?

   You rub your hands thoroughly with soap and water, then rinse them under running water.

   • It kills every microbe and makes the hands completely sterile.
   • It removes visible dirt but cannot reduce the number of microbes.
   • It loosens dirt and microbes so the water can carry them away.

   Consider what happens during rinsing.

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   • It loosens dirt and microbes so the water can carry them away.

   Handwashing does not need to kill every microbe to help. Removing microbes also reduces the chance of spreading them.

4. 4. Chọn đáp án đúng.

   What mainly causes the dough to expand?

   Bread dough containing yeast rises while resting, before it goes into the oven.

   • Gas released by the yeast becomes trapped in the dough.
   • Heat from the yeast turns the dough's water into steam.
   • Yeast cells absorb water and become large enough to stretch the dough.

   Think about the small air pockets inside a slice of bread.

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   • Gas released by the yeast becomes trapped in the dough.

   Yeast produces carbon dioxide as it uses sugars. The dough traps this gas, creating bubbles that make it rise.

5. 5. Chọn đáp án đúng.

   How do these microbes help return nutrients to the soil?

   A compost pile contains fallen leaves, food scraps, bacteria, and fungi.

   • They turn the dead material into seeds for new plants.
   • They break down the dead material, releasing nutrients.
   • They preserve the dead material, keeping its nutrients sealed inside.

   Consider why the original leaves become difficult to recognize.

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   • They break down the dead material, releasing nutrients.

   Decomposition recycles nutrients from once-living material. Without decomposers, dead material would build up and many nutrients would remain unavailable.

6. 6. Chọn đáp án đúng.

   Which statement explains why refrigerated food still has a limited safe storage time?

   Leftovers are cooled promptly and stored in a refrigerator.

   • Refrigeration kills all microbes, but the food creates new ones.
   • Refrigeration makes all bacteria harmless without affecting their growth.
   • Refrigeration slows microbial growth but does not stop every microbe from growing.

   Slowing a process is different from stopping it completely.

   Show solution

   • Refrigeration slows microbial growth but does not stop every microbe from growing.

   Some microbes can grow at refrigerator temperatures. Keeping food cold reduces risk, but it does not make food sterile.

7. 7. Chọn đáp án đúng.

   Which environment would allow a virus to multiply?

   Unlike bacteria, viruses cannot make copies of themselves using nutrients alone.

   • Living cells that the virus can infect
   • A sterile sugar solution containing no cells
   • An empty container supplied with warmth and oxygen

   A virus needs more than food and suitable temperatures.

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   • Living cells that the virus can infect

   Viruses depend on machinery inside suitable host cells to produce new viruses. They cannot multiply independently.

8. 8. Chọn đáp án đúng.

   Why would antibiotics not treat the cause of this cold?

   A clinician diagnoses a cold caused by a virus and finds no bacterial infection.

   • Antibiotics work against this virus only after a fever develops.
   • Antibiotics target bacteria, not the virus causing the cold.
   • Antibiotics work against this virus only after symptoms become severe.

   The type of microbe matters more than how severe the symptoms are.

   Show solution

   • Antibiotics target bacteria, not the virus causing the cold.

   Many antibiotics attack bacterial structures or processes that viruses do not have. A separate bacterial infection would require its own assessment.

9. 9. Chọn đáp án đúng.

   What does this example show about bacteria in the body?

   A healthy adult's gut contains a large community of bacteria. Some help break down dietary fiber.

   • Bacteria are useful only after they have caused an infection.
   • A healthy gut must eventually remove all its bacteria.
   • The presence of bacteria does not automatically mean someone is ill.

   Consider the difference between a resident microbe and a disease-causing microbe.

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   • The presence of bacteria does not automatically mean someone is ill.

   Many microbes normally live in or on the body. Their effects depend on factors such as their type, location, and the person's health.

10. 10. Chọn đáp án đúng.

    What does the normal smell tell you about the chicken's safety?

    Some cooked chicken smells normal, but no one knows how long it has been left at room temperature.

    • It does not rule out harmful microbes or their toxins.
    • It confirms that cooking killed every harmful bacterium.
    • It guarantees the chicken will be safe after reheating.

    Not every food safety problem produces an obvious warning.

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    • It does not rule out harmful microbes or their toxins.

    Some harmful microbes and toxins cause no noticeable change in smell or appearance. Reheating also does not reliably destroy every toxin.

11. 11. Chọn đáp án đúng.

    How can this preparation help during a later infection?

    A vaccine prepares the immune system to recognize a particular virus before a person encounters that virus.

    • The vaccine stays in the blood and directly kills every future virus.
    • Immune memory can help the body respond more quickly.
    • The body no longer needs an immune response because exposure is blocked.

    Think about the advantage of recognizing something you have encountered before.

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    • Immune memory can help the body respond more quickly.

    Vaccination can reduce the risk of severe illness even when it does not prevent every infection. Protection does not require the vaccine itself to remain in the blood.

12. 12. Chọn đáp án đúng.

    Why did resistant bacteria become a larger share of the population?

    A bacterial population contains a few bacteria that are already resistant to an antibiotic. After treatment and further growth, most bacteria in the population are resistant.

    • The antibiotic taught every bacterium how to survive.
    • The medicine weakened each time a bacterium encountered it.
    • Resistant bacteria were more likely to survive and produce new bacteria.

    Focus on which bacteria were already present and which survived.

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    • Resistant bacteria were more likely to survive and produce new bacteria.

    Treatment can favor bacteria with existing resistance while killing those without it. The bacterial population becomes more resistant; the person does not become resistant to the medicine.