Question

section 8 - 1 energy and life (pages 201 - 203)
key concepts
where do plants get the energy they need to produce food?
what is the role of atp in cellular activities?
autotrophs and heterotrophs (page 201)

1. where does the energy of food originally come from?
2. complete the table describing the types of organisms.

chemical energy and atp (page 202)

1. what is one of the principal chemical compounds that cells use to store energy?
2. how is atp different from adp?
3. label each part of the atp molecule illustrated below.
4. when a cell has energy available, how can it store small amounts of that energy?

Explanation:

1. The energy of food originally comes from the sun. This is because autotrophs (like plants) use sunlight in photosynthesis to convert light energy into chemical energy stored in food.

2.

Type	Description	Examples
Heterotrophs	Organisms that obtain energy from the food they eat	Animals (e.g., lions, rabbits), fungi, most bacteria

1. One of the principal chemical compounds that cells use to store energy is ATP (adenosine tri - phosphate).
2. ATP (adenosine tri - phosphate) has three phosphate groups, while ADP (adenosine di - phosphate) has two phosphate groups. The bond between the second and third phosphate in ATP is a high - energy bond. When this bond is broken (releasing a phosphate group), energy is released for cellular work, and ATP becomes ADP.
3. (Assuming the ATP molecule has three main parts: adenine, ribose, and phosphate groups). The left - hand part (the double - ring structure) is adenine, the middle part (pentagon - shaped) is ribose, and the right - hand part (the "P" groups) are phosphate groups.
4. When a cell has energy available, it can store small amounts of that energy by adding a phosphate group to ADP (adenosine di - phosphate) to form ATP (adenosine tri - phosphate). The reaction is \(ADP + Pi+energy

ightarrow ATP\), where \(Pi\) is an inorganic phosphate.

Answer:

1. The sun.

2.

Type	Description	Examples
Heterotrophs	Organisms that obtain energy from the food they eat	Animals (e.g., lions, rabbits), fungi, most bacteria

1. ATP (adenosine tri - phosphate).
2. ATP has three phosphate groups and ADP has two phosphate groups.
3. Adenine (left - hand part), ribose (middle part), phosphate groups (right - hand part).
4. By adding a phosphate group to ADP to form ATP.