Aerobic & Anaerobic respiration

What is respiration?

An exothermic reaction that releases energy from sugar molecules like glucose.

What do organisms need energy for? Give 5 examples.

• Muscle contraction to allow movement

• Chemical reactions to build larger molecules from smaller molecules

• Chemical reactions to combine smaller molecules into larger molecules

• Keeping warm - to maintain a constant temperature suitable for enzyme activity

• To move substances around the cell

What is aerobic respiration?

The process of releasing energy from glucose using oxygen.

What is the word & symbol equation for aerobic respiration?

glucose + oxygen → carbon dioxide + water

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Where does aerobic respiration take place in the cell?

Mitochondria.

What is anaerobic respiration?

The process of releasing energy from glucose without oxygen.

What is anaerobic respiration in animals?

The process of releasing energy involving the incomplete breakdown of glucose into lactic acid, without oxygen.

What is the word equation for anaerobic respiration in animals?

glucose → lactic acid

What is anaerobic respiration in plants & yeast?

Breaking down glucose in the absence of oxygen to produce ethanol & carbon dioxide.

What do we call anaerobic respiration in yeast?

Fermentation.

What is the word equation for anaerobic respiration in plants & yeast?

glucose → ethanol + carbon dioxide

Which releases the most energy, aerobic or anaerobic respiration? Why?

Aerobic respiration, because anaerobic respiration doesn’t break down the glucose molecule completely, so doesn’t release as much energy.

Why don’t animals always carry out aerobic respiration?

It requires oxygen, and during intense exercise there may not be enough supplied.

What can the ethanol produced by anaerobic respiration be used for?

Making alcoholic drinks.

How is anaerobic respiration used in baking bread?

1. When baking bread, yeast is added to the mixture

2. There’s limited oxygen in the bread mixture, so the yeast will respire anaerobically

3. This produces carbon dioxide which forms little bubbles of gas

4. The pockets of gas make the break light & fluffy

Compare aerobic & anaerobic respiration.

• Oxygen is needed for aerobic respiration, oxygen isn’t needed for anaerobic respiration

• In aerobic respiration, glucose is broken down completely, in anaerobic respiration, glucose breakdown is incomplete

• The products of aerobic respiration is carbon dioxide & water, in plants the products of anaerobic respiration is carbon dioxide & ethanol, in animals the product of anaerobic respiration is lactic acid

• Aerobic respiration releases a lot more energy, anaerobic respiration releases little energy