Cellular Respiration Quiz

List two reasons why food is important to living organisms.

• Food serves as a source of energy.

• Food provides a set of raw materials that serve as building blocks for the building of new molecules.

Answer explanation

Food is crucial for living organisms as it provides energy necessary for growth and maintenance, and it supplies raw materials for synthesizing new molecules, essential for cellular functions and overall health.

Name the principal molecule that stores and releases energy as needed to the cells of a living organism.

• ATP

• ADP

Answer explanation

ATP, or adenosine triphosphate, is the principal molecule that stores and releases energy for cellular processes. It is often referred to as the energy currency of the cell, making it the correct answer.

Describe two basic differences between ADP and ATP.

Answer explanation

ADP (adenosine diphosphate) has two phosphate groups, while ATP (adenosine triphosphate) has three. Additionally, ATP is the primary energy carrier in cells, whereas ADP is produced when ATP loses a phosphate group.

List three basic components of an ATP molecule.

• The nitrogen base, adenine.

• The five-carbon sugar, ribose.

• Three phosphate molecules.

Answer explanation

An ATP molecule consists of three main components: the nitrogen base adenine, the five-carbon sugar ribose, and three phosphate groups. These components are essential for ATP's role in energy transfer in cells.

What is the role of ATP in living cells?

Answer explanation

ATP, or adenosine triphosphate, serves as the primary energy currency in living cells, providing the energy needed for various cellular processes, including metabolism, muscle contraction, and active transport.

How does ADP become ATP?

Answer explanation

ADP becomes ATP through the addition of a phosphate group in a process called phosphorylation, typically during cellular respiration or photosynthesis, which stores energy in the high-energy bond of ATP.

What happens when a phosphate molecule is removed from ATP?

Answer explanation

When a phosphate molecule is removed from ATP, it becomes ADP (adenosine diphosphate). This process releases energy, which can be used for cellular activities.

List three cellular processes that require the energy from ATP.

Answer explanation

Three cellular processes that require ATP energy include muscle contraction, active transport across cell membranes, and protein synthesis. ATP provides the necessary energy for these vital functions in cells.

Fill in the blanks. Energy flows into an ecosystem in the form of ___a___ and leaves as ___b___.

• sunlight

• heat

Answer explanation

Energy flows into an ecosystem primarily as sunlight, which is harnessed by plants through photosynthesis. It leaves the ecosystem as heat, a byproduct of energy transfer and metabolic processes.

Describe the relationship that exists between photosynthesis and cellular respiration.

Answer explanation

Photosynthesis converts light energy into chemical energy (glucose), while cellular respiration breaks down glucose to release energy for cellular activities. They are interconnected; the products of one process serve as the reactants for the other.