Q: Using the caterpillar diagram, calculate the production efficiency for the caterpillar. Use the formula $$\text{Production Efficiency} = \frac{\text{Energy used for growth}}{\text{Energy assimilated}} \times 100.$$

$$\frac{33}{(200-100)} \times 100 = 33\%$$

Q: Refer to the trophic pyramid diagram. If primary producers have 10,000 J of energy, and tertiary consumers have 10 J, what is the approximate trophic efficiency between each level?

$$\frac{100}{1,000} \times 100 = 10\%$$

Q: If a caterpillar eats 300 J of plant material, eliminates 150 J as feces, and uses 100 J for cellular respiration, what is its production efficiency?

$$\frac{50}{(300-150)} \times 100 = 33.3\%$$

Question 1

Which statement best explains why energy flows through ecosystems but matter cycles within them, as shown in the first diagram?

Accepted Answer

Energy enters as sunlight and exits as heat, while matter is reused by organisms and decomposers.

Question 2

Based on the second diagram, which nutrient is most likely the limiting factor for phytoplankton growth in the collection sites?

Accepted Answer

Ammonium, because its enrichment led to a dramatic increase in phytoplankton density.

Question 3

Using the caterpillar diagram, calculate the production efficiency for the caterpillar. Use the formula $$	ext{Production Efficiency} = \frac{	ext{Energy used for growth}}{	ext{Energy assimilated}} 	imes 100.$$

Accepted Answer

$$\frac{33}{(200-100)} 	imes 100 = 33\%$$

Question 4

Refer to the trophic pyramid diagram. If primary producers have 10,000 J of energy, and tertiary consumers have 10 J, what is the approximate trophic efficiency between each level?

Accepted Answer

$$\frac{100}{1,000} 	imes 100 = 10\%$$

Question 5

Based on the decomposition graph, what is the relationship between mean annual temperature and the percent of mass lost from leaf litter?

Accepted Answer

As temperature increases, decomposition rate increases.

Question 6

Why are carnivorous plants often found in bogs, based on the decomposition and nutrient cycling data?

Accepted Answer

Bogs have low decomposition rates, so nutrients are scarce and plants must obtain nutrients from prey.

Question 7

Which process in the carbon cycle diagram is responsible for moving carbon from the biotic to the abiotic environment?

Accepted Answer

Respiration

Question 8

If a caterpillar eats 300 J of plant material, eliminates 150 J as feces, and uses 100 J for cellular respiration, what is its production efficiency?

Accepted Answer

$$\frac{50}{(300-150)} 	imes 100 = 33.3\%$$

Question 9

Why do birds and mammals typically have lower production efficiency compared to insects?

Accepted Answer

They use more energy for cellular respiration to maintain body temperature.

Question 10

Which two factors most commonly limit primary production in terrestrial ecosystems?

Accepted Answer

Water and nutrients

Question 11

What is the main reason most food chains are short, as illustrated by the energy pyramid?

Accepted Answer

Energy is lost at each trophic level, limiting the number of levels.

Question 12

Which ecosystem type would you expect to have more nutrients in the trees than in the soil, based on nutrient cycling?

Accepted Answer

Tropical rainforest

Question 13

What is the difference between gross primary production (GPP) and net primary production (NPP)?

Accepted Answer

GPP is the total energy captured by photosynthesis; NPP is GPP minus energy used for respiration.

Question 14

How do satellites help ecologists measure net primary production (NPP) in ecosystems?

Accepted Answer

By detecting changes in plant biomass and chlorophyll concentrations.

Question 15

What is upwelling, and how does it affect coastal ecosystems?

Accepted Answer

Upwelling brings nutrient-rich water to the surface, boosting primary production.

Question 16

Which three nutrients are most limiting for primary productivity on land?

Accepted Answer

Nitrogen, phosphorus, potassium

Question 17

If you wanted to grow your own food and spend the least amount of energy, would you be better off eating plant protein or animal protein?

Accepted Answer

Plant protein, because it requires fewer energy transfers and losses.

Question 18

Which process is responsible for converting atmospheric CO$$_2$$ into organic molecules in the carbon cycle diagram?

Accepted Answer

Photosynthesis

Question 19

What essential role do decomposers play in nutrient cycling within ecosystems?

Accepted Answer

They convert organic matter into inorganic nutrients, making them available to producers.

Systems Ecology: Energy Flow and Nutrient Cycling Study Guide

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