Bacteria: Definition, Types, Benefits, Diagram, Classification, Risks & Examples

Question : Comprehension:
 Read the given passage and answer the questions that follow.

Key factors influencing subway air pollution will include station depth, date of construction, type of ventilation (natural/air conditioning), types of brakes (electromagnetic or conventional brake pads) and wheels (rubber or steel) used on the trains, train frequency and more recently the presence or absence of platform screen-door systems. In particular, much subway particulate matter is sourced from moving train parts such as wheels and brake pads, as well as from the steel rails and power-supply materials, making the particles dominantly iron-containing. To date, there is no clear epidemiological indication of abnormal health effects on underground workers and commuters. New York subway workers have been exposed to such air without significant observed impacts on their health, and no increased risk of lung cancer was found among subway train drivers in the Stockholm subway system. But a note of caution is struck by the observations of scholars who found that employees working on the platforms of Stockholm underground, where PM concentrations were greatest, tended to have higher levels of risk markers for cardiovascular disease than ticket sellers and train drivers. The dominantly ferrous particles are mixed with particles from a range of other sources, including rock ballast from the track, biological aerosols such as bacteria and viruses, and air from the outdoors, and driven through the tunnel system on turbulent air currents generated by the trains themselves and ventilation systems.

Question

What is the tone of the speaker?

Option 1: Serious

Option 2: Pessimistic

Option 3: Joyful

Option 4: Informal

Question : Comprehension:

Read the following passage and answer the questions.

All foodstuffs change. Green fruits become ripe and eggs go bad or rotten. It is the enzymes naturally present in each food which bring about the complex chemical changes that lead first to ripening and then to rotting.

How does one control the activity of enzymes, bacteria, yeasts and moulds in food? All of them require air, moisture and a certain temperature, usually somewhere near the body temperature, to be active. Depriving them of one or more of these will suppress them. All microorganisms can be killed by heat sterilisation. This simply means heating the food to high enough temperatures by boiling, deep or shallow frying, roasting, baking and, for milk particularly, pasteurisation. After such sterilisation, if the food is sealed in airtight containers, it can be kept for a long time. A certain water content in food is necessary for microorganisms to be active. Drying in the sun is a simple way of bringing down the moisture level so low that the enzymes and microorganisms cannot flourish.

Some chemicals can suppress undesirable activity. The addition of salt, vinegar, spices and oil or sugar syrup are other ways of preventing foods from going bad. If heating kills, freezing inactivates the enzymes and microorganisms. This is what happens in a refrigerator, in which fruits, vegetables and milk can be kept for fairly long periods. For meat and fish, even colder temperatures, below freezing point, are necessary for preservation. All foods which are kept cold in this way, once taken out and returned to room temperature, are again subject to spoilage and change.

Question:
What action does freezing have on the enzymes?

Option 1: It activates them

Option 2: It kills them

Option 3: It preserves them

Option 4: It inactivates them

Question : Comprehension:
Read the given passage and answer the questions that follow.

Key factors influencing subway air pollution will include station depth, date of construction, type of ventilation (natural or air conditioning), types of brakes (electromagnetic or conventional brake pads) and wheels (rubber or steel) used on the trains, train frequency, and more recently, the presence or absence of platform screen-door systems.

In particular, much subway particulate matter is sourced from moving train parts such as wheels and brake pads, as well as from the steel rails and power supply materials, making the particles predominantly iron-containing.

To date, there is no clear epidemiological indication of abnormal health effects on underground workers and commuters. New York subway workers have been exposed to such air without significant observed impacts on their health, and no increased risk of lung cancer was found among subway train drivers in the Stockholm subway system.

But a note of caution is struck by the observations of scholars who found that employees working on the platforms of Stockholm underground, where PM concentrations were greatest, tended to have higher levels of risk markers for cardiovascular disease than ticket sellers and train drivers.

The dominantly ferrous particles are mixed with particles from a range of other sources, including rock ballast from the track, biological aerosols such as bacteria and viruses, and air from the outdoors, and driven through the tunnel system on turbulent air currents generated by the trains themselves and ventilation systems.

Question:
Inferring from the passage, what is the most practical way of reducing the health risk of subway life?

Option 1: Generating ventilation systems.

Option 2: Opting for other transportation modes.

Option 3: Wearing face masks during journey.

Option 4: Reducing subway commutation.

Question : Comprehension:

Read the following passage and answer the questions.

All foodstuffs change. Green fruits become ripe and eggs go bad or rotten. It is the enzymes naturally present in each food which bring about the complex chemical changes that lead first to ripening and then to rotting.

How does one control the activity of enzymes, bacteria, yeasts and moulds in food? All of them require air, moisture and a certain temperature, usually somewhere near the body temperature, to be active. Depriving them of one or more of these will suppress them. All microorganisms can be killed by heat sterilisation. This simply means heating the food to high enough temperatures by boiling, deep or shallow frying, roasting, baking and, for milk particularly, pasteurisation. After such sterilisation, if the food is sealed in airtight containers, it can be kept for a long time. A certain water content in food is necessary for microorganisms to be active. Drying in the sun is a simple way of bringing down the moisture level so low that the enzymes and microorganisms cannot flourish.

Some chemicals can suppress undesirable activity. The addition of salt, vinegar, spices and oil or sugar syrup are other ways of preventing foods from going bad. If heating kills, freezing inactivates the enzymes and microorganisms. This is what happens in a refrigerator, in which fruits, vegetables and milk can be kept for fairly long periods. For meat and fish, even colder temperatures, below freezing point, are necessary for preservation. All foods which are kept cold in this way, once taken out and returned to room temperature, are again subject to spoilage and change.

Question:
Which of these is NOT required for the growth of bacteria?

Option 1: Air

Option 2: Optimum temperature

Option 3: Chemicals

Option 4: Moisture

Question : Comprehension:

Read the following passage and answer the questions.

All foodstuffs change. Green fruits become ripe and eggs go bad or rotten. It is the enzymes naturally present in each food which bring about the complex chemical changes that lead first to ripening and then to rotting.

How does one control the activity of enzymes, bacteria, yeasts and moulds in food? All of them require air, moisture and a certain temperature, usually somewhere near the body temperature, to be active. Depriving them of one or more of these will suppress them. All microorganisms can be killed by heat sterilisation. This simply means heating the food to high enough temperatures by boiling, deep or shallow frying, roasting, baking and, for milk particularly, pasteurisation. After such sterilisation, if the food is sealed in airtight containers, it can be kept for a long time. A certain water content in food is necessary for microorganisms to be active. Drying in the sun is a simple way of bringing down the moisture level so low that the enzymes and microorganisms cannot flourish.

Some chemicals can suppress undesirable activity. The addition of salt, vinegar, spices and oil or sugar syrup are other ways of preventing foods from going bad. If heating kills, freezing inactivates the enzymes and microorganisms. This is what happens in a refrigerator, in which fruits, vegetables and milk can be kept for fairly long periods. For meat and fish, even colder temperatures, below freezing point, are necessary for preservation. All foods which are kept cold in this way, once taken out and returned to room temperature, are again subject to spoilage and change.

Question:
The main theme of the passage is:

Option 1: Chemicals in foodstuff

Option 2: Ripening of fruit

Option 3: Production of micro-organisms

Option 4: Preservation of food