4.2

Question 1

What is nitrogen fixation?

Answer 1

The process by which nitrogen gas (N₂) from the atmosphere is converted into ammonia (NH₃) or related nitrogenous compounds, making it usable for plants.

Question 2

What is denitrification?

Answer 2

The process by which bacteria convert nitrates (NO₃⁻) back into nitrogen gas (N₂), returning it to the atmosphere and completing the nitrogen cycle.

Question 2

What is nitrification?

Answer 2

The conversion of ammonia (NH₃) into nitrites (NO₂⁻) and then nitrates (NO₃⁻) by bacteria, making nitrogen available to plants in the soil.

Question 3

What are the inputs and outputs of photosynthesis?

Answer 3

Inputs: Carbon dioxide (CO₂), water (H₂O), and sunlight. Outputs: Glucose (C₆H₁₂O₆) and oxygen (O₂).

Question 4

What are the inputs and outputs of cellular respiration?

Answer 4

Inputs: Glucose (C₆H₁₂O₆) and oxygen (O₂). Outputs: Carbon dioxide (CO₂), water (H₂O), and ATP (energy).

Question 5

What type of organisms perform photosynthesis?

Answer 5

Autotrophs, primarily plants, algae, and some bacteria.

Question 6

How do humans affect the nitrogen cycle?

Answer 6

By using synthetic fertilizers and fossil fuels, which increase nitrogen levels in the environment, leading to pollution and eutrophication

Question 6

What type of organisms perform cellular respiration?

Answer 6

Both autotrophs and heterotrophs, including plants, animals, fungi, and many bacteria.

Question 7

How do humans affect the carbon cycle?

Answer 7

Through activities like burning fossil fuels and deforestation, which increase carbon dioxide (CO₂) levels in the atmosphere.

Question 8

How does BTB (Bromothymol Blue) work as a pH indicator?

Answer 8

BTB changes color based on pH levels: it turns yellow in acidic solutions and blue in basic solutions, indicating the presence of CO₂.

Question 9

Predict the color change of BTB in a test tube with a plant in light conditions.

Answer 9

The BTB would likely turn blue as the plant performs photosynthesis, consuming CO₂ and raising the pH.

Question 9

Differentiate between how energy and carbon flow through a food chain.

Answer 9

Energy flows in one direction, decreasing at each trophic level, while carbon cycles through the ecosystem, being reused and recycled by organisms.

Question 10

Predict the color change of BTB in a test tube with both a plant and animal in the dark.

Answer 10

The BTB would likely turn yellow, as both the plant and animal would produce CO₂ through respiration, lowering the pH.

Question 11

Predict the color change of BTB in a test tube with an animal in the dark.

Answer 11

The BTB would likely turn yellow as the animal produces CO₂ through cellular respiration, lowering the pH.

Question 11

In what way does cellular respiration contribute to the carbon cycle?

Answer 11

Cellular respiration releases CO₂ back into the atmosphere as organisms break down glucose for energy, cycling carbon within ecosystems.

Question 11

How does photosynthesis impact atmospheric carbon dioxide levels?

Answer 11

Photosynthesis reduces atmospheric CO₂ as plants take it in to produce glucose, helping to regulate global carbon levels.

Question 11

What is the main role of nitrification in the nitrogen cycle?

Answer 11

It transforms ammonia into nitrates, which plants can absorb and use to build proteins and nucleic acids.

Question 11

Predict the color change of BTB in a test tube with both a plant and animal in the light.

Answer 11

The BTB may stay blue, as the plant’s photosynthesis could balance the animal’s CO₂ production, maintaining a relatively neutral pH.

Question 11

Why is denitrification important for the nitrogen cycle?

Answer 11

It prevents excess nitrogen accumulation in soil by returning nitrogen gas to the atmosphere, balancing the nitrogen cycle.