Practice GED Pre-test Science

1. Medical laboratories often need to separate blood into its three main parts. Blood is made primarily of red blood cells, white blood cells, and a liquid called plasma. This separation can be easily done because each part has a different density.

The diagram shows blood added to a test tube containing a medium called Ficoll-Hypaque, as shown in tube A. After tube A is processed, the blood separates into the three parts shown in tube B. Which of the following statements about the densities of the three parts is correct?

White blood cells are more dense than red blood cells.

Red blood cells are denser than either white blood cells or plasma.

Red cells are less dense than whole blood.

Plasma is the densest component.

All blood cells are equally dense.

The correct answer is that red blood cells are denser than either white blood cells or plasma. This is because in the diagram, the red blood cells settle at the bottom of the test tube, indicating that they have a higher density compared to the white blood cells and plasma which remain suspended above.

Explanation

The correct answer is that red blood cells are denser than either white blood cells or plasma. This is because in the diagram, the red blood cells settle at the bottom of the test tube, indicating that they have a higher density compared to the white blood cells and plasma which remain suspended above.

2. Water covers approximately what percentage of the earth's surface?

25 percent

55 percent

70 percent

90 percent

None of these

Approximately 70 percent of the Earth's surface is covered by water. This includes the oceans, seas, lakes, rivers, and other bodies of water. Water is essential for supporting life and plays a crucial role in various natural processes, such as weather patterns, climate regulation, and the water cycle. The abundance of water on Earth is a unique characteristic that distinguishes our planet from others in the solar system.

Explanation

Approximately 70 percent of the Earth's surface is covered by water. This includes the oceans, seas, lakes, rivers, and other bodies of water. Water is essential for supporting life and plays a crucial role in various natural processes, such as weather patterns, climate regulation, and the water cycle. The abundance of water on Earth is a unique characteristic that distinguishes our planet from others in the solar system.

3. Which of the following processes shows an example of solar energy converting to chemical energy?

Green plants making their own food

Ocean tides generating electricity

Prevailing winds causing windmills to spin

Uranium producing heat to make steam

None of the above

Green plants making their own food is an example of solar energy converting to chemical energy through the process of photosynthesis. During photosynthesis, plants use sunlight to convert carbon dioxide and water into glucose and oxygen. The energy from sunlight is stored in the chemical bonds of glucose, which can be later used by the plant for growth, reproduction, and other metabolic processes. This process is essential for the survival of plants and forms the basis of the food chain, as other organisms rely on plants for energy.

Explanation

Green plants making their own food is an example of solar energy converting to chemical energy through the process of photosynthesis. During photosynthesis, plants use sunlight to convert carbon dioxide and water into glucose and oxygen. The energy from sunlight is stored in the chemical bonds of glucose, which can be later used by the plant for growth, reproduction, and other metabolic processes. This process is essential for the survival of plants and forms the basis of the food chain, as other organisms rely on plants for energy.

4.

10:30 p.m.

10:38 p.m.

11:04 p.m.

10:12 p.m.

None of these

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Explanation

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5. A food chain is a group or organisms related to each other in their feeding habits. One organism is eaten by a second one, which in turn is fed upon by a third one. The food chain starts with energy from the Sun. As each organism grows and is eaten, only about 10 percent of the Sun's energy is transferred at each step. People who live in areas of the world where food is scarce eat very little meat and depend on grains and other plants. Based on the ideas presented, which of the following statements best supports such eating habits?

Plants store energy in sugar molecules.

Plants taste better than meat from animals.

More than 90 percent of the energy in plants never reaches people who eat the animals raised on the plants.

Plants take up less space than grazing animals.

It is easier to grow plants than raise animals.

The statement "More than 90 percent of the energy in plants never reaches people who eat the animals raised on the plants" best supports the idea that people who live in areas where food is scarce depend on grains and other plants. This statement suggests that the energy obtained from plants is more efficient and beneficial for humans compared to consuming animals that have consumed those plants. It implies that by directly consuming plants, people can obtain a higher percentage of the Sun's energy and meet their nutritional needs more effectively.

Explanation

The statement "More than 90 percent of the energy in plants never reaches people who eat the animals raised on the plants" best supports the idea that people who live in areas where food is scarce depend on grains and other plants. This statement suggests that the energy obtained from plants is more efficient and beneficial for humans compared to consuming animals that have consumed those plants. It implies that by directly consuming plants, people can obtain a higher percentage of the Sun's energy and meet their nutritional needs more effectively.

6.

The drop will pass through the oil and water and mix with the corn-syrup layer.

The drop will be trapped between the water and oil layers.

The drop will be trapped in the water level.

The drop of corn syrup will float on the top layer.

The drop will mix with the oil layer.

The drop will pass through the oil and water layers because corn syrup has a higher density than both oil and water. Since the drop is denser than the oil and water, it will sink through them and mix with the corn-syrup layer, which is denser than the drop.

Explanation

The drop will pass through the oil and water layers because corn syrup has a higher density than both oil and water. Since the drop is denser than the oil and water, it will sink through them and mix with the corn-syrup layer, which is denser than the drop.

7. Fossils similar to marine life found in the oceans today, have been found in rocks on top of mountains. This can be explained by:

The rocks which contain the fossils were once under the ocean.

Marine organisms were once able to breathe air.

Weather has moved the fossils from the oceans to the mountains.

The marine life can live on land or in the ocean.

None of the above

The correct answer is that the rocks which contain the fossils were once under the ocean. This explanation suggests that the mountains were once submerged under the ocean, and over time, tectonic forces pushed the rocks upward, bringing them to their current elevation. This process is known as uplift, and it can explain how marine fossils ended up on top of mountains.

Explanation

The correct answer is that the rocks which contain the fossils were once under the ocean. This explanation suggests that the mountains were once submerged under the ocean, and over time, tectonic forces pushed the rocks upward, bringing them to their current elevation. This process is known as uplift, and it can explain how marine fossils ended up on top of mountains.

8. Which of the following describes the shoulder joint?

Pivot joint

Saddle joint

Ball and socket joint

Hinge joint

None of these

The shoulder joint is a ball and socket joint. This type of joint allows for a wide range of movement in multiple directions, including flexion, extension, abduction, adduction, and rotation. The rounded head of the humerus bone fits into the shallow socket of the scapula, allowing for a high degree of mobility in the shoulder joint.

Explanation

The shoulder joint is a ball and socket joint. This type of joint allows for a wide range of movement in multiple directions, including flexion, extension, abduction, adduction, and rotation. The rounded head of the humerus bone fits into the shallow socket of the scapula, allowing for a high degree of mobility in the shoulder joint.

9. Use the following passage to answer questions 9 and 10.

According to the passage, which of the following statements are true:

High blood pressure is an effect of light pollution.

Light pollution can cause hearing problems in humans and animals.

Animals have trouble navigating because of medical waste companies.

Vehicle and aircraft pollution is caused by radioactive pollutants.

Whales have been known to beach themselves because the global warming has caused some glacier to melt.

The passage states that high blood pressure is an effect of light pollution.

Explanation

The passage states that high blood pressure is an effect of light pollution.

10. Use the diagram below to determine the products of photosynthesis of plant cells. The diagram shows the relationship between photosynthesis and respiration.

Oxygen and energy

Glucose and oxygen

Carbon dioxide and glucose

Carbon dioxide and water

None of the above

The diagram shows the relationship between photosynthesis and respiration. During photosynthesis, plants use carbon dioxide and water to produce glucose and oxygen. Therefore, the correct answer is "glucose and oxygen".

Explanation

The diagram shows the relationship between photosynthesis and respiration. During photosynthesis, plants use carbon dioxide and water to produce glucose and oxygen. Therefore, the correct answer is "glucose and oxygen".

11.

According to the table above, what could be concluded about the general relationship between a planet's distance from the sun and its temperature?

The temperature on Neptune is the coldest.

Neptune is the farthest planet from the sun.

The average temperature on Venus is higher than that of Mercury because Venus is closer to the sun.

The closer the planet is to the sun, the colder it is on the planet.

The further the planet is from the sun, the colder it is on the planet.

Based on the information provided, it can be concluded that the further a planet is from the sun, the colder it is on the planet. This can be inferred from the fact that Neptune, which is the farthest planet from the sun, has the coldest temperature. Additionally, the statement that the average temperature on Venus is higher than that of Mercury because Venus is closer to the sun further supports this conclusion.

Explanation

Based on the information provided, it can be concluded that the further a planet is from the sun, the colder it is on the planet. This can be inferred from the fact that Neptune, which is the farthest planet from the sun, has the coldest temperature. Additionally, the statement that the average temperature on Venus is higher than that of Mercury because Venus is closer to the sun further supports this conclusion.

12. The graph below shows temperature changes as a result of heating ice. Study the diagram, then answer question that follows.

The liquid is freezing.

The liquid is evaporating.

The solid is melting.

The solid is freezing.

Nothing is happening because ice cannot be heated.

The graph shows temperature changes as a result of heating ice. As the temperature increases, the ice transitions from a solid state to a liquid state. This is indicated by the upward slope in the graph, which shows that the temperature is increasing over time. Therefore, the correct answer is that the solid is melting.

Explanation

The graph shows temperature changes as a result of heating ice. As the temperature increases, the ice transitions from a solid state to a liquid state. This is indicated by the upward slope in the graph, which shows that the temperature is increasing over time. Therefore, the correct answer is that the solid is melting.

13. The smell of an ammonia solution used to clean a floor can quickly be detected throughout a house. Scientists explain this by theorizing that the gas molecules from the ammonia are in continuous high-speed motion, drifting rapidly and permeating the air. Which statement best demonstrates the strength of this theory?

Reason, as opposed to experimentation, is superior to any explanation found through chemical testing.

Scientists have unanimously agreed on this theory since Thomas Graham's experiments in the 1820s.

Scientists have observed tiny smoke particles moved by unseen particles in a rapid, irregular fashion.

The possibility of another theory being formed to explain the phenomenon as well is very remote.

None of the above

The statement "Scientists have observed tiny smoke particles moved by unseen particles in a rapid, irregular fashion" best demonstrates the strength of the theory because it provides empirical evidence that supports the idea of gas molecules moving rapidly and permeating the air. This observation aligns with the theory that gas molecules from the ammonia solution are in continuous high-speed motion, supporting the explanation given.

Explanation

The statement "Scientists have observed tiny smoke particles moved by unseen particles in a rapid, irregular fashion" best demonstrates the strength of the theory because it provides empirical evidence that supports the idea of gas molecules moving rapidly and permeating the air. This observation aligns with the theory that gas molecules from the ammonia solution are in continuous high-speed motion, supporting the explanation given.

14.

Some snakes that appear ferocious are actually quite harmless.

Some types of nonpoisonous snakes very closely resemble poisonous ones.

Most snakes feed on rats and mice.

Snakes are dangerous.

Snakes feed very infrequently.

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Explanation

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15.

How does the pitch change when a bell is moving?

Through what material does sound travel best?

How much faster does light travel than sound?

What is the best material to use in musical instruments?

How does the pitch of an instrument change when it's held underwater?

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Explanation

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16.

The birth rate of the eagles increased.

The death rate of the eagles exceeded the birth rate.

The emigration rate of the eagles decreased.

The specific area reached its carrying capacity for the eagle population.

None of the above

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Explanation

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17.

Clay soil would form a good liner if a person built a pond.

Sandy soil would make a good lining for a toxic waste site.

Clay soil would be a good foundation for a large building.

Clay soil would work well in a drain field.

A sandy lake bottom would prevent water from seeping out of the lake.

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Explanation

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18. Which of the following BEST explains why a concrete floor feels colder than a wooden floor if both are at 21ºC:

Wood is alive and concrete is not

Concrete is much less elastic than wood

Concrete conducts heat better than wood

Wood is not as dense as concrete

None of these

Concrete conducts heat better than wood. This means that heat is transferred more easily through concrete than through wood. When both the concrete floor and wooden floor are at the same temperature, the concrete floor will feel colder because it is more efficient at conducting heat away from the body. This is why the concrete floor feels colder to the touch compared to the wooden floor.

Explanation

Concrete conducts heat better than wood. This means that heat is transferred more easily through concrete than through wood. When both the concrete floor and wooden floor are at the same temperature, the concrete floor will feel colder because it is more efficient at conducting heat away from the body. This is why the concrete floor feels colder to the touch compared to the wooden floor.

19. Use the passage below to answer questions 17 and 18.

According to the passage, symptoms such as nausea and dizziness in a heat exhaustion victim indicates that the person most likely needs to ____________________.

Go immediately to the hospital

Be immersed in a tub of cold water

Sponged with cool water

Be given more salt water

Sweat more

The passage suggests that symptoms such as nausea and dizziness in a heat exhaustion victim indicate that the person most likely needs to be given more salt water. This is because heat exhaustion can lead to dehydration and an imbalance of electrolytes, including sodium, which can be replenished by consuming salt water.

Explanation

The passage suggests that symptoms such as nausea and dizziness in a heat exhaustion victim indicate that the person most likely needs to be given more salt water. This is because heat exhaustion can lead to dehydration and an imbalance of electrolytes, including sodium, which can be replenished by consuming salt water.

20.

Compresses and cools.

Expands and warms.

Expands and cools.

Compresses and warms.

Condenses and lowers in pressure.

When a gas is compressed, its molecules are forced closer together, resulting in an increase in temperature. On the other hand, when a gas expands, its molecules move further apart, causing a decrease in temperature. Therefore, the correct answer is "expands and cools" because the gas is expanding, which leads to a decrease in temperature.

Explanation

When a gas is compressed, its molecules are forced closer together, resulting in an increase in temperature. On the other hand, when a gas expands, its molecules move further apart, causing a decrease in temperature. Therefore, the correct answer is "expands and cools" because the gas is expanding, which leads to a decrease in temperature.

21. According to the passage, which type of pollution(s) can a car cause?

Air pollution

Noise pollution

Light pollution

Both A and B

All of the above

A car can cause air pollution by emitting harmful gases and particulate matter into the atmosphere. It can also contribute to noise pollution through the noise generated by its engine and tires. Additionally, cars can contribute to light pollution through the headlights and other lighting systems. Therefore, the correct answer is "all of the above" as a car can cause air pollution, noise pollution, and light pollution.

Explanation

A car can cause air pollution by emitting harmful gases and particulate matter into the atmosphere. It can also contribute to noise pollution through the noise generated by its engine and tires. Additionally, cars can contribute to light pollution through the headlights and other lighting systems. Therefore, the correct answer is "all of the above" as a car can cause air pollution, noise pollution, and light pollution.

22. According to the passage, which statement below is true?

Heat stroke is more serious than heat exhaustion because heat stroke victims do not sweat.

Heat stroke is more serious than heat exhaustion because heat stroke victims cannot take in water.

Heat exhaustion is more serious than heat stroke.

When large amounts of water and salt are lost through excessive sweating a person always has a heat stroke.

None of the above are true

Heat stroke is more serious than heat exhaustion because heat stroke victims do not sweat. This is true because when the body overheats, the body's cooling system fails and the person stops sweating. Sweating is the body's way of regulating temperature, so the absence of sweating indicates a more severe condition. Heat exhaustion, on the other hand, is characterized by excessive sweating, fatigue, and dizziness, which are less severe symptoms compared to the absence of sweating in heat stroke.

Explanation

Heat stroke is more serious than heat exhaustion because heat stroke victims do not sweat. This is true because when the body overheats, the body's cooling system fails and the person stops sweating. Sweating is the body's way of regulating temperature, so the absence of sweating indicates a more severe condition. Heat exhaustion, on the other hand, is characterized by excessive sweating, fatigue, and dizziness, which are less severe symptoms compared to the absence of sweating in heat stroke.

23.

This experiment was probably set up to determine ___________________.

How much energy is converted into heat

The pressure caused by an electric current

The pH of water during electrolysis

How much mechanical energy the battery produces

The experiment was most likely set up to determine how much energy is converted into heat. This can be inferred from the fact that the other options are not directly related to energy conversion or heat. The pH of water during electrolysis and the pressure caused by an electric current are not directly related to energy conversion. Similarly, the amount of mechanical energy produced by the battery is not relevant to the experiment's objective. Therefore, the most logical explanation is that the experiment aimed to measure the amount of energy converted into heat.

Explanation

The experiment was most likely set up to determine how much energy is converted into heat. This can be inferred from the fact that the other options are not directly related to energy conversion or heat. The pH of water during electrolysis and the pressure caused by an electric current are not directly related to energy conversion. Similarly, the amount of mechanical energy produced by the battery is not relevant to the experiment's objective. Therefore, the most logical explanation is that the experiment aimed to measure the amount of energy converted into heat.