Lesson 1: Energy and the Human Body

Question 1

Metabolism

Answer 1

The functional unit of the human body is the cell.

Each cell performs thousands of interlinked chemical reactions.
The sum of these reactions is called metabolism.

Question 2

Respiration

Answer 2

Metabolic process involve changes in
energy.

Energy is made available to the body
through the process of cellular
respiration.

This process begins with simple sugar
molecules that get converted to carbon
dioxide and water through a series of
oxidation reactions that release energy.

These simple sugars come from more
energy rich molecules that get
converted to simple sugars through the
process of digestion.

Question 3

Food and Energy

Answer 3

The energy rich molecules that drive metabolism are obtained through the
food that we eat.

Knowing the energy content of different foods is very important in
maintaining a health lifestyle.

Food packaging provides information on the energy value of the food. This
is often expressed in calories (joules or kilojoules)per unit serving.

Question 4

Calorimetry

Answer 4

The energy value of food is determined through combustion
analysis.

This is done through the use of a calorimeter.

The bomb calorimeter is a special type of calorimeter used to
measure the heat of combustion of food.
The food is burned to completion
after being ignited electrically.

The heat released as it burns is
measured by recording the
temperature rise in a known
mass of pure water.

We can use the equation :

q = mcΔT