Question

energy transfer between tropic levels
net different productivity at tropic levels
conversion efficiency
lower tropic level higher tropic level
organism a 2187cal → organism b 25 cal
organism k 11000cal → organism l 3200 cal

1. one of the above pairings represents a producer→ primary consumer energy transfer. the other represents primary consumer → secondary consumer energy transfer. which is which? defend your selection.
2. how can a 175 lb man who eats 7 lbs of food in a given day, not gain weight?
3. energy lost at each link of the food chain is ultimately lost as
4. summarize and diagram the 3 different pyramids in the space below.

Explanation:

1. Producers - like plants - convert solar energy to chemical energy. Primary consumers eat producers. Secondary consumers eat primary consumers. Energy transfer from producers to primary consumers is less efficient than from primary to secondary consumers in general. The transfer from Organism A to Organism B has a lower conversion efficiency (25/2187 ≈ 1.14%) which is typical of producer - primary consumer transfer. The transfer from Organism K to Organism L has a higher conversion efficiency (3200/11000 ≈ 29.09%) which is more in line with primary - secondary consumer transfer.
2. A 175 - lb man who eats 7 lbs of food in a day may not gain weight if the energy content of the food is used up by his metabolic processes (such as basal metabolic rate, physical activity, digestion). If the energy intake from the food equals the energy expenditure, there is no net gain in weight.
3. Energy lost at each link of the food chain is ultimately lost as heat. This is due to the second law of thermodynamics which states that energy transformations are not 100% efficient and some energy is always dissipated as heat.
4. The three different pyramids in ecology are the pyramid of numbers (shows the number of organisms at each trophic level), the pyramid of biomass (shows the total mass of living organisms at each trophic level), and the pyramid of energy (shows the amount of energy available at each trophic level). In a pyramid of numbers, the number of producers is usually the highest and decreases as we move up the trophic levels. In a pyramid of biomass, the biomass of producers is generally the greatest and decreases at higher trophic levels. In a pyramid of energy, the energy available at the producer level is the highest and decreases at each successive trophic level because of energy losses at each transfer.

Answer:

1. Organism A → Organism B is producer → primary consumer energy transfer because of low conversion efficiency. Organism K → Organism L is primary consumer → secondary consumer energy transfer due to higher conversion efficiency.
2. If energy intake from food equals energy expenditure through metabolism and activity.
3. Heat.
4. Pyramid of numbers: Number of organisms per trophic level, highest at producer level and decreases up - trophic levels. Pyramid of biomass: Total mass of organisms per trophic level, greatest at producer level and decreases. Pyramid of energy: Amount of energy per trophic level, highest at producer level and decreases due to energy losses at transfers.