Q: Which of the following equations correctly represents the photosynthetic process in autotrophs?

$$6\mathrm{CO}_2 + 6\mathrm{H}_2\mathrm{O} + \text{light energy} \rightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\mathrm{O}_2$$

Question 1

Which of the following best describes an autotroph in an ecosystem?

Accepted Answer

An organism that synthesizes complex organic molecules from CO$$_2$$ and other simple inorganic molecules using energy from a non-biological source.

Question 2

Which process is responsible for the majority of energy capture in terrestrial ecosystems?

Accepted Answer

Photosynthesis in plants and algae

Question 3

In the context of nutrient cycling, which of the following is a correct description of the geochemical cycle?

Accepted Answer

Movement of nutrients in their inorganic form within and among the atmosphere, lithosphere, and hydrosphere.

Question 4

If only 1% of the sun’s energy that reaches Earth’s surface is used for photosynthesis, what happens to the remaining 99%?

Accepted Answer

It is reflected or absorbed as heat, and not used by living organisms.

Question 5

Which of the following best explains why only about 10% of energy is transferred from one trophic level to the next?

Accepted Answer

Most energy is lost as heat due to metabolism and not all biomass is consumed.

Question 6

Which of the following is NOT a major input to the biosphere from the atmosphere?

Accepted Answer

Release of methane from decomposition

Question 7

A farmer applies excess nitrogen fertilizer to a field. Which of the following is a likely consequence for the local ecosystem?

Accepted Answer

Eutrophication of nearby water bodies due to runoff

Question 8

Which of the following equations correctly represents the photosynthetic process in autotrophs?

Accepted Answer

$$6\mathrm{CO}_2 + 6\mathrm{H}_2\mathrm{O} + 	ext{light energy} ightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\mathrm{O}_2$$

Question 9

Which type of heterotroph consumes dead organic matter and helps recycle nutrients in an ecosystem?

Accepted Answer

Scavenger

Question 10

Which of the following is a trade-off that plants may face in acquiring energy, nutrients, and water?

Accepted Answer

Increasing leaf area for photosynthesis can increase water loss through transpiration.

Question 11

Which of the following is an example of a biogeochemical cycle?

Accepted Answer

Movement of carbon between the atmosphere, biosphere, and lithosphere

Question 12

Which of the following is a correct statement about energy flow in ecosystems?

Accepted Answer

Energy flows in one direction and is eventually lost as heat.

Question 13

Which of the following is a major output to the atmosphere from the biosphere?

Accepted Answer

Release of methane during decomposition

Question 14

Which of the following best describes the role of decomposers in nutrient cycling?

Accepted Answer

They break down dead organic matter, returning nutrients to the soil.

Question 15

A food web in a forest ecosystem includes plants, herbivores, carnivores, and decomposers. If a disease drastically reduces the decomposer population, what is the most likely consequence?

Accepted Answer

Nutrient cycling will slow down, leading to accumulation of dead organic matter.

Question 16

Which of the following is a correct sequence in the movement of nutrients in the biogeochemical cycle?

Accepted Answer

Organic form → inorganic form → organic form

Question 17

Which of the following is a major input to the hydrosphere from the lithosphere?

Accepted Answer

Deposition of nutrients in floodplains and backwaters as part of dead organic matter

Question 18

Which of the following human activities most directly increases atmospheric CO$$_2$$ levels?

Accepted Answer

Deforestation and burning of fossil fuels

Question 19

Which of the following is a correct statement about the fate of energy in biomass after it is consumed by a predator?

Accepted Answer

Some energy is lost as heat and some is used for metabolism and growth.

Question 20

Which of the following best describes the difference between energy flow and nutrient cycling in ecosystems?

Accepted Answer

Energy flows in one direction and is lost as heat, while nutrients are recycled.

Energy and Nutrient Flow in Ecosystems (Chapter 42 Study Notes)

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