Question 1

Which of the following best describes the main advantage of the C$$_4$$ photosynthetic pathway over the C$$_3$$ pathway in plants?

Accepted Answer

C$$_4$$ plants reduce internal CO$$_2$$ concentrations, allowing fewer stomata to be open and conserving water.

Question 2

A plant growing in an arid environment is most likely to use which photosynthetic pathway, and why?

Accepted Answer

CAM pathway, because it fixes carbon at night, minimizing water loss.

Question 3

Which equation correctly represents the overall reaction for photosynthesis?

Accepted Answer

$$6CO_2 + 6H_2O + solar\ energy \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 4

Which of the following is a key difference between chemosynthetic and photosynthetic autotrophs?

Accepted Answer

Chemosynthetic autotrophs use inorganic molecules (such as hydrogen sulfide) for energy, while photosynthetic autotrophs use light.

Question 5

Why do herbivores often need to consume large amounts of plant material compared to carnivores?

Accepted Answer

Plant tissues have a high C:N ratio, meaning they are low in nitrogen, which is essential for herbivores.

Question 6

Which of the following best explains why detritivores play a key role in nutrient cycling?

Accepted Answer

They break down non-living organic matter, releasing nutrients back into the ecosystem.

Question 7

A scientist measures the rate of photosynthesis in a plant as photon flux density increases. She observes that the rate increases linearly at first, then levels off. What is the best explanation for this observation?

Accepted Answer

The plant's photosynthetic machinery becomes saturated at high light intensities.

Question 8

Which of the following is NOT an essential plant nutrient obtained primarily from the soil?

Accepted Answer

Sodium

Question 9

According to optimal foraging theory, what is the main prediction about the behavior of organisms?

Accepted Answer

Natural selection will favor organisms that are most effective at acquiring energy, given resource limitations.

Question 10

Which of the following best describes a Type 2 functional response in animals?

Accepted Answer

Feeding rate is partially limited by search and handling time, resulting in a curve that rises quickly then levels off.

Question 11

A plant is growing in nutrient-poor soil. According to optimal foraging theory, how is its root:shoot ratio likely to compare to a plant in fertile soil?

Accepted Answer

It will have a higher root:shoot ratio.

Question 12

Which of the following is a disadvantage of CAM photosynthesis?

Accepted Answer

Low rates of photosynthesis.

Question 13

Which of the following statements about ecological stoichiometry is correct?

Accepted Answer

Plants have a higher C:N ratio than herbivores, requiring herbivores to eat more to obtain enough nitrogen.

Question 14

Which of the following is a chemical defense that plants use against herbivores?

Accepted Answer

Tannins

Question 15

Which group of organisms is capable of using the widest variety of energy sources?

Accepted Answer

Prokaryotes (Bacteria, Archaea)

Question 16

A carnivore and its prey are engaged in a co-evolutionary race. Which of the following is NOT a likely prey defense?

Accepted Answer

Increased photosynthetic rate

Question 17

Which of the following best describes the principle of allocation in optimal foraging theory?

Accepted Answer

Organisms must compromise between competing resource demands when energy is limited.

Question 18

Which of the following is a real-world example of chemosynthetic autotrophy?

Accepted Answer

Sulfur-oxidizing bacteria living near oceanic rift vents

Question 19

Which of the following is a correct statement about the three feeding methods of heterotrophs?

Accepted Answer

Detritivores feed on non-living organic matter, usually plant remains.

Question 20

Which of the following best explains why fresh detritus may still be difficult for detritivores to digest?

Accepted Answer

It may still have considerable chemical defenses present.

Energy and Nutrient Relations (General Biology Study Notes)

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