Reading Passage Problems BI O Metabolic Rate Energy for our activities is provi...

Reading Passage Problems

BI O Metabolic Rate Energy for our activities is provided by the chemical energy of the foods we eat. The absolute value of the rate of conversion of this chemical energy into other forms of energy (ΔE/ Δt) is called the metabolic rate. The metabolic rate depends on many factors—a person’s weight, physical activity, the efficiency of bodily processes, and the fat-muscle ratio. Table 6.8

lists the metabolic rates of people under several different conditions and in several different units of measure: 1 kcal = 1000 calories = 4186 J. Dieticians call a kcal simply a Cal. A piece of bread provides about 70 kcal of metabolic energy.

In 1 hour of heavy exercise a 68-kg person metabolizes 600 kcal - 90 kcal = 510 kcal more energy than when at rest. Typically, reducing kilocalorie intake by 3500 kcal (either by burning it in exercise or not consuming it in the first place) results in a loss of 0.45 kg of body mass (the mass is lost through exhaling carbon dioxide—the product of metabolism).

Suppose that a 90-kg person walks for 1 hour each day for a year, expending 50,000 extra kilocalories of metabolic energy (in addition to his normal resting metabolic energy use). What approximately is the person’s mass at the end of the year, assuming his food consumption does not change?

(a) 57 kg (b) 61 kg (c) 64 kg (d) 66 kg (e) 67 kg