Question

energy pyramids: tying it all together
name kayleigh hatathlie
energy pyramids represent the amount of energy available to each trophic level (producers and consumers).

1. give a reasonable explanation as to why the energy is represented by a pyramid shape.
2. what process does the grass use to harness this energy?
3. what could be assumed about the amount of producers in pyramids a and b based on the amount of sunlight hitting

the earth in each pyramid?

1. in the table below, calculate the percentage of energy that is transferred from one level of the pyramid to another for

all the levels.

1. describe the energy transfer among the organisms in the pyramid. use percentage data to support your answer.

a. you may have noticed the averages of energy transferred to each level are around 10%. we call this the 10%
rule. in pyramid b, assume a lion has consumed a young elephant. how many kilocalories could be passed
using this rule?

Explanation:

1. Energy pyramids are shaped like pyramids because energy transfer between trophic levels is inefficient. Only about 10% of the energy from one level is passed on to the next level (10% Rule). As we move up the trophic levels (from producers to primary consumers to secondary consumers etc.), the amount of available energy decreases, creating a pyramid - like structure.
2. Grass (a producer) uses photosynthesis to harness energy. In photosynthesis, plants use sunlight, carbon dioxide, and water to produce glucose (a form of stored energy) and oxygen.
3. In Pyramid A, the amount of sunlight hitting the Earth is \(92,900,000\) kcal and in Pyramid B it is \(12,500,000\) kcal. Since producers rely on sunlight for energy (through photosynthesis), we can assume that there are more producers in Pyramid A (because there is more sunlight available for photosynthesis to occur and support a larger producer population).

4.

• Pyramid A:
• % of energy transferred from sunlight to producers: \(\frac{3,800,000}{92,900,000}\times100\approx4.09\%\)
• % of energy transferred from producers to primary consumers (grass to grasshopper): \(\frac{450,000}{3,800,000}\times 100\approx11.84\%\)
• % of energy transferred from primary to secondary consumers (grasshopper to warthog): \(\frac{50,000}{450,000}\times100\approx11.11\%\)
• % of energy transferred from secondary to tertiary consumers (warthog to lion): \(\frac{2,500}{50,000}\times100 = 5\%\)
• Average energy transferred: \(\frac{4.09 + 11.84+11.11 + 5}{4}\approx7.51\%\)
• Pyramid B (assuming values for each level similar to standard ecological pyramids and using the 10% rule as a guide, but since no exact values for each level in B are given in the problem - like Pyramid A. If we assume a simple 10% transfer at each level):
• % of energy transferred from sunlight to producers: \(10\%\) (using 10% rule assumption as a base for calculation, since no exact data for B's producer level is given in the problem like A)
• % of energy transferred from producers to primary consumers: \(10\%\)
• % of energy transferred from primary to secondary consumers: \(10\%\)
• % of energy transferred from secondary to tertiary consumers: \(10\%\)
• Average energy transferred: \(10\%\)

1. Energy transfer in the pyramid is unidirectional. Energy flows from the sun to producers (via photosynthesis). Producers are then consumed by primary consumers. Only about 10% (on average) of the producer's energy is passed to the primary consumer. The primary consumer is then consumed by a secondary consumer, and again about 10% of the primary consumer's energy is passed on. This pattern continues up the trophic levels. For example, in Pyramid A, from grass (\(3,800,000\) kcal) to grasshopper (\(450,000\) kcal) is approximately an 11.84% transfer, which is close to the 10% rule.
2. a. Pyramid B - Lion and young elephant (assuming elephant is a primary or secondary consumer):

If we assume the young elephant has \(x\) kcal of energy. Using the 10% rule, the lion would receive \(0.1x\) kcal. But if we assume the elephant is at a certain level. For example, if the base (sunlight) is \(12,500,000\) kcal. If producers get \(10\%\) (i.e., \(1,250,000\) kcal), primary consumers get \(10\%\) of that (\(125,000\) kcal), secondary consumers (elephant) get \(10\%\) of primary consumers (\(12,500\) kcal), and the lion (tertiary consumer) gets \(10\%\) of the elephant's energy. So the lion would get \(1250\) kcal.

Answer:

1. Energy transfer is inefficient (10% rule), so energy decreases up trophic levels.
2. Photosynthesis.
3. More producers in Pyramid A (more sunlight for photosynthesis).

4.

	Pyramid A	Pyramid B
% of energy transferred from producers to primary consumers	\(\approx11.84\%\)	\(10\%\) (assumed)
% of energy transferred from primary to secondary consumers	\(\approx11.11\%\)	\(10\%\) (assumed)
% of energy transferred from secondary to tertiary consumers	\(5\%\)	\(10\%\) (assumed)
Average energy transferred	\(\approx7.51\%\)	\(10\%\) (assumed)

1. Energy flows unidirectionally with ~10% transfer at each level (e.g., Pyramid A grass to grasshopper ~11.84% transfer).
2. a. \(1250\) kcal (assuming 10% rule at each level from sunlight to lion).