bio

BIO 112

Name: _________________________________________ Section: _____

Ecological Energy Requirements

Assignment #3 In ecological systems, a rough rule of thumb is that when energy is transferred from plants to plant-eaters or from prey to predator, the efficiency of the transfer is only about 10%. Much of this inefficiency is a consequence of the second law of thermodynamics. Another way to think of this is that eating 1 calorie of meat from an animal is the ecological equivalent of eating 10 calories of plant material. Humans are considered omnivores because we can eat both plants and animals. The choices we make about what to eat can have significant ecological consequences.

• Complete the chart by calculating the ecological energy requirements for four different diets, each of which provides a total of 2,000 dietary calories per day. (5 pts.)

• Answer Questions 1, 2, 3, and 4 on the next page.

The number of calories consumed/day = 2,000 calories x percent diet

To calculate ecologically equivalent calories/day:

• For plant diet portion: calories consumed x 1 • For animal diet portion: calories consumed x 10 


Diet Number of calories consumed /day

Ecologically equivalent calories / day

Total ecologically equivalent calories/day

100% plant

0% animal

90% plant 1800 (2000 x 90%)

1800 (1800 x 1) 3800

(= 1800 + 2000)10% animal 200 (2000 x 10%)

2000 (200 x 10)

50% plant

50% animal

0% plant

100% animal

BIO 112

REMEMBER:

USE COMPLETE, GRAMMATICALLY CORRECT SENTENCES TO ANSWER THESE QUESTIONS.

QUESTIONS 1. How many ecologically equivalent calories would it take to support you for a year

(daily amount x 365 days) for each of the 4 diets. (0.25 pts each)

a) 100% plant: 0% animal (vegan) –

b) 90% plant: 10% animal –

c) 50% plant: 50% animal –

d) 0% plant: 100% animal –

2.

A) How does the ecological impact from a diet consisting strictly of animal products (100% animal; e.g., milk, other dairy products, eggs, and meat) compare with that of a strictly vegan diet (100% plant)? (0.5 pt)

B) How many additional ecologically equivalent calories do you consume each day by including as little as 10% of your calories from animal sources (90% plant: 10% animal) (0.5 pt.)?

3.

A) What percentages of the calories in your own diet do you think come from plant sources versus animal sources (% plant vs. % animal)? (0.5 pt)

B) Estimate the ecological impact of your own diet based on ecologically equivalent calories, compared to a strictly vegan diet. (0.5 pt)

4. Describe two (2) different challenges of providing food for the growing human population, especially as people in many poorer nations develop a taste for an American style diet rich in animal protein and fat. (1 point for each challenge; 2 pts.)