5.7.1 The Need for Cellular Respiration

Question 1

Why is cellular respiration needed?

Answer 1

Living organisms are composed of cells, and within each cell, many activities and processes are constantly being carried out to maintain life

Work in a living organism requires energy and usable carbon compounds.
eg:
- Transporting substances across membranes
- Anabolic reactions
- Movement
- Maintaining body temperature

Question 2

How does respiration create a source of energy and materials?

Answer 2

For nearly all organisms the sun is the primary source of energy

The reactions of photosynthesis store energy in organic molecules
Light energy from the sun is transformed into chemical potential energy in the synthesis of carbohydrates
The carbohydrates formed are then used in the synthesis of ATP (from their breakdown) or are combined and modified to form all the usable organic molecules that are essential for all metabolic processes within the plant
Photosynthesis is carried out by the first organism in a food chain, such as plants and some other small organisms

Respiration in all living cells releases energy from the breakdown of organic molecules

Respiration involves the transfer of chemical potential energy from nutrient molecules (such as carbohydrates, fats and proteins) into a usable energy form (through the synthesis of ATP) that can be used for work within an organism

Question 3

What is the glucose equation?

Answer 3

glucose + oxygen → carbon dioxide + water + energy

C6H1206 + 6 O2 → 6 CO2 + 6 H20 + 2870kJ

Autotrophs are organisms that are able to synthesise their own usable carbon compounds from carbon dioxide in the atmosphere through photosynthesis

Heterotrophs don’t have this ability. They require a supply of pre-made usable carbon compounds which they get from their food