Biology: Middle School: Grades 6, 7 and 8 Quiz - Biofuels (Questions)

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This middle school Biology quiz takes a closer look at biofuels. These are either combustible gasses like methane or combustible liquids such as plant oils, which can be burnt to release energy. Biofuels are more environmentally friendly alternatives to fossil fuels because they are part of the current carbon cycle. Burning fossil fuels releases carbon that has been locked out of the carbon cycle for millions of years.

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This causes a problem because it overloads the Earth's natural recycling system that keeps the level of gasses in the air in balance. It only takes small increases in the percentages of gasses like methane and carbon dioxide to create a runaway greenhouse effect in which the surface temperature of the Earth increases beyond that which could sustain life. Most scientists believe that human use of fossil fuels is creating this greenhouse effect and causing global warming, whilst some believe that the changes we are seeing are natural.

Liquids obtained from plants can help to lessen the amount of carbon imported to the present day from the past. Gasoline can be diluted with a percentage of ethanol (an alcohol) that is made from the fermentation of plants. These plants are part of the current carbon cycle and so will not increase the overall level of carbon dioxide in our atmosphere. There are other advantages too, such as lower emissions of other gasses like the toxic carbon monoxide. The main argument against this is that land that could be used for growing food crops will be taken up by crops grown to produce bioethanol to add to gasoline. Diesel can be replaced with biodiesel. This is made from plant oils that have been treated to make them burn in diesel engines. Biodiesels can be made from used cooking oils, soy bean oil or even animal fats.

Biogas is made in a generator which is loaded with human waste, animal dung or food waste which would otherwise end up in the environment. Waste materials like these release methane and carbon dioxide into the atmosphere as they decay. This biofuel is mainly methane and is produced by anaerobic fermentation of the waste products. Aerobic fermentation would produce carbon dioxide instead of methane and that cannot be usefully used. Biogas can be passed through pipes to local homes where it can be used as a fuel for cooking. In some places, the biogas is used as a fuel for generating electricity for the local community.

Which biofuels are combustible liquids? Is methane a biofuel? See how much you understand about biofuels by trying this quiz.

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1. What are biofuels made from?
[ ] Coal
[ ] Oil
[ ] Gas
[ ] Animal and plant material
2. Biogas is primarily made up of which gas?
[ ] Methane
[ ] Oxygen
[ ] Carbon dioxide
[ ] Hydrogen
3. Biogas is made by which process?
[ ] Aerobic respiration
[ ] Alcoholic fermentation
[ ] Anaerobic fermentation
[ ] Respiration
4. Biogas generators can be filled with which of the following?
[ ] Air
[ ] Water
[ ] Feces
[ ] Nitrogen
5. In a biogas generator, what does the animal or plant material supply?
[ ] Carbohydrate (sugar)
[ ] Protein
[ ] Fat
[ ] Water
6. Methane is a greenhouse gas and contributes to...
[ ] the weather
[ ] global warming
[ ] ozone depletion
[ ] respiration
7. Which of the following is not caused by global warming?
[ ] Increased temperature of the Earth
[ ] Rise in sea levels
[ ] Increased biodiversity
[ ] Climate change
8. What is biodiversity?
[ ] The number of species
[ ] The population of humans
[ ] The variety of birds
[ ] The number of trees
9. Biogas is produced at a faster rate if the temperature is...
[ ] increased
[ ] decreased
[ ] unchanged
[ ] heated for longer
10. Biogas generators are useful in developing countries such as Africa, because they easily and cheaply get rid of what?
[ ] Fuel
[ ] Air
[ ] Waste
[ ] Soil
Biology: Middle School: Grades 6, 7 and 8 Quiz - Biofuels (Answers)
1. What are biofuels made from?
[ ] Coal
[ ] Oil
[ ] Gas
[x] Animal and plant material
Biofuels come from organisms
2. Biogas is primarily made up of which gas?
[x] Methane
[ ] Oxygen
[ ] Carbon dioxide
[ ] Hydrogen
Methane is a useful fuel
3. Biogas is made by which process?
[ ] Aerobic respiration
[ ] Alcoholic fermentation
[x] Anaerobic fermentation
[ ] Respiration
Biogas is made by a special type of anaerobic respiration called anaerobic fermentation. This is not the same process which occurs in the muscles of our body
4. Biogas generators can be filled with which of the following?
[ ] Air
[ ] Water
[x] Feces
[ ] Nitrogen
Human and animal feces can be used as well as food waste. So it helps to keep the environment clean as well as providing a useful fuel
5. In a biogas generator, what does the animal or plant material supply?
[x] Carbohydrate (sugar)
[ ] Protein
[ ] Fat
[ ] Water
The carbohydrate is changed into the product methane
6. Methane is a greenhouse gas and contributes to...
[ ] the weather
[x] global warming
[ ] ozone depletion
[ ] respiration
Global warming is the gradual increase in the average temperature of the surface of the Earth
7. Which of the following is not caused by global warming?
[ ] Increased temperature of the Earth
[ ] Rise in sea levels
[x] Increased biodiversity
[ ] Climate change
Global warming leads to reduced biodiversity
8. What is biodiversity?
[x] The number of species
[ ] The population of humans
[ ] The variety of birds
[ ] The number of trees
Biodiversity is important to the health of the planet. It refers not just to the number of different species but also to the genetic variations within each species
9. Biogas is produced at a faster rate if the temperature is...
[x] increased
[ ] decreased
[ ] unchanged
[ ] heated for longer
About 35 degrees C is the optimum temperature
10. Biogas generators are useful in developing countries such as Africa, because they easily and cheaply get rid of what?
[ ] Fuel
[ ] Air
[x] Waste
[ ] Soil
The raw materials are free and recycled into a useful product, biofuel, which can be used for many purposes