2.2 Energy & Biomass in Ecosystems

Based on the example of a caterpillar consuming $2,000$ kJ of oak leaves, what specific percentage of energy is typically converted into new biomass?

• 90%

• 50%

• 10%

• 1%

What is the direct ecological consequence of the 90% "energy tax" that occurs at each trophic level transition?

• An increase in the number of top-tier predators to balance the system.

• A reduction in the total number of links possible within a food chain.

• The evolution of consumers into producers to bypass energy loss.

• A significant increase in the biomass of organisms at higher trophic levels.

From the perspective of a "producer" in the hidden economy of nature, what is the primary goal of Gross Primary Productivity (GPP)?

• To maximise the "profit" (NPP) available for secondary consumers.

• To pay for the metabolic "living expenses" of other heterotrophs.

• To capture as much solar energy as possible to serve as the organism's "total income."

• To eliminate respiration (R) to ensure a 100% efficient system.

The argument that humans should harvest from the "lowest level possible" to feed the planet most efficiently reflects which underlying worldview?

• Anthropocentric: focusing on managing ecosystems as a resource to meet human needs sustainably.

• Biocentric: valuing all organisms equally regardless of their position in the food chain.

• Technocentric: believing that future technology will eventually eliminate the 90% energy loss rule.

• Ecocentric: prioritising the protection of top-tier predators over human food security.

Evaluate the efficiency of meat production compared to crop production as presented in the video’s "energy bank" analogy.

• Meat is more efficient because it contains more concentrated calories per gram.

• Crops are less efficient because they lose a large portion of energy to heat during photosynthesis.

• Meat is less efficient because it requires paying an additional 90% "energy tax" already incurred by the animal.

• Both are equally efficient since they both eventually lead back to solar energy.

In the "Plant's Energy Budget" system, what does the variable R (Respiration) represent?

• The total energy input from the sun.

• The biomass stored in leaves, stems, and roots.

• The system process that accounts for metabolic living expenses and heat loss.

• The final output available to the rest of the food chain.

Which of the following phrases from the video demonstrates the use of "loaded" or metaphorical language rather than neutral scientific phrasing?

• "The total rate at which plants store chemical energy."

• "The system has simply run out of cash."

• "The tiny fraction left becomes new tissue."

• "A resource can be harvested without compromising its ability to regenerate."

The concept of "Sustainable Yield" as defined in the video is most accurately applied to which scale of environmental management?

• Local: only applicable to a single blade of grass.

• National: limited to the food systems of a specific country.

• Regional: applicable only to ocean fisheries or corn fields.

• Global: a fundamental principle for managing resources across the entire planet.

Explain how the formula $NPP = GPP - R$ determines the "profit" of an ecosystem.

• It describes the total solar energy captured by the leaves.

• It identifies the biomass available to consumers after a producer’s metabolic needs are met.

• It justifies why most energy in an ecosystem is lost as indigestible waste.

• It calculates the 10% efficiency of a caterpillar’s growth.

How does the concept of "Indigestible Waste" connect to the "Inefficient Hand-off" of energy between trophic levels?

• Waste increases the Gross Primary Productivity of the next level.

• Waste is a primary reason why only 10% of ingested energy becomes new biomass.

• Waste is the heat lost during the respiration of the consumer.

• Waste represents the "profit" that supports the growth of big animals like lions.