Unit 3 Review: Biogeochemical Cycles

Which of the following is NOT a way carbon moves through the carbon cycle?

• Photosynthesis

• Respiration

• Precipitation

• Decomposition

Answer explanation

Precipitation is not a process in the carbon cycle. Carbon moves through photosynthesis, respiration, and decomposition, but precipitation refers to water falling from the atmosphere, not carbon movement.

Tags

NGSS.MS-LS2-3

NGSS.MS-LS1-6

Which process in the carbon cycle is responsible for converting sugar back into carbon dioxide?

• Photosynthesis

• Respiration

• Decomposition

• Combustion

Answer explanation

Respiration is the process that converts sugar into energy, releasing carbon dioxide as a byproduct. This is essential in the carbon cycle, as it returns CO2 to the atmosphere, contrasting with photosynthesis, which absorbs it.

Tags

NGSS.HS-LS1-7

NGSS.HS-LS2-5

While hiking in a forest, Maya and Leo observe that many trees have been cut down. How does this deforestation affect the movement of carbon between Earth's spheres?

• Carbon is stored in the leaves of the trees.

• Carbon is released from the soil into the atmosphere.

• Carbon is transferred from the forest to the ocean.

• Carbon is released from the trees into the air.

Answer explanation

Deforestation leads to the release of carbon stored in trees into the atmosphere. When trees are cut down, the carbon they contain is emitted as CO2, contributing to greenhouse gas levels and affecting climate change.

Tags

NGSS.MS-LS2-3

NGSS.MS-LS1-6

In the process of photosynthesis, how is the conservation of mass demonstrated?

• By the creation of new atoms

• By the destruction of some atoms

• By the rearrangement of existing atoms

• By doubling the number of atoms

Answer explanation

In photosynthesis, mass conservation is shown by the rearrangement of existing atoms from carbon dioxide and water into glucose and oxygen, rather than creating or destroying atoms.

Tags

NGSS.MS-PS1-5

During a biology field trip, Isla observes animals and plants in a forest. She wonders which process is responsible for transferring carbon from the biosphere back to the atmosphere. What process is Isla thinking about?

• Respiration by animals and plants

• Photosynthesis in plants

• Formation of fossil fuels

• Absorption of carbon dioxide by oceans

Answer explanation

Isla is thinking about respiration by animals and plants, which releases carbon dioxide back into the atmosphere, completing the carbon cycle. This process contrasts with photosynthesis, which absorbs carbon dioxide.

Aria is studying the movement of carbon in nature. Which statement correctly describes the carbon cycle?

• Carbon remains in one place and does not change forms.

• Carbon moves between living things, the atmosphere, and the earth through various processes.

• Carbon is only present in plants.

• Carbon disappears when animals breathe out.

Answer explanation

The correct statement highlights that carbon is constantly moving through the carbon cycle, involving living organisms, the atmosphere, and the earth, through processes like photosynthesis and respiration.

Tags

NGSS.MS-LS2-3

NGSS.MS-LS1-6

Samuel is curious about how the environment supports life. He wants to know what role the carbon cycle plays in nature. Why is the carbon cycle necessary for living things?

• It produces water for plants.

• It helps recycle carbon, which living things need to survive.

• It removes all nitrogen from the soil.

• It creates sunlight for energy.

Answer explanation

The carbon cycle is essential because it recycles carbon, a vital element for all living organisms. Without this cycle, life would struggle to obtain the carbon needed for processes like photosynthesis and respiration.

Tags

NGSS.MS-LS2-3

Volunteers working to restore a local pond are evaluating several strategies. Which of the following actions would most likely help reduce the amount of carbon dioxide present in the pond?

• an increase in runoff from nearby areas

• a decrease in the population of aquatic plants

• an increase in the number of algae in the pond

• a decrease in organic matter entering the pond

Answer explanation

A decrease in organic matter entering the pond reduces the food source for decomposers, which in turn lowers the production of carbon dioxide through decomposition, helping to reduce CO2 levels.

Tags

NGSS.MS-LS2-3

NGSS.MS-LS1-6

Aria and Rohan are conducting an experiment to observe the gases released during cellular respiration in both plants and animals. Which statement about their findings is true?

• Oxygen is a waste product of cellular respiration in both plants and animals.

• Oxygen is a waste product of cellular respiration in plants, but not in animals.

• Carbon dioxide is a waste product of cellular respiration in both plants and animals.

• Carbon dioxide is a waste product of cellular respiration in plants, but not in animals.

Answer explanation

The correct statement is that carbon dioxide is a waste product of cellular respiration in both plants and animals. While plants also produce oxygen during photosynthesis, they release carbon dioxide during respiration, similar to animals.

Nora is studying the water cycle and observes that water from the soil moves through plants and is released back into the air. Which process returns water to the atmosphere from plants?

• Precipitation

• Transpiration

• Condensation

• Sedimentation

Answer explanation

Transpiration is the process by which water is absorbed by plant roots, moves through the plant, and is released as water vapor into the atmosphere. This is how plants return water to the air in the water cycle.

Tags

NGSS.MS-ESS2-4