9.3 Respiration

Question 1

What is aerobic respiration?

Answer 1

A chemical reaction that your body uses to create energy. It happens in the mitochondria.

Question 2

What is the equation for aerobic respiration?

Answer 2

glucose + oxygen → carbon dioxide + water (+energy)

Question 3

How does glucose get into the cell?

Answer 3

Glucose molecules are absorbed into the bloodstream where they dissolve into the blood plasma, the dissolved glucose then diffuses into the cells that need it for respiration.

Question 4

How does oxygen get into the cell for aerobic respiration?

Answer 4

The air is breathed in and diffuses into the bloodstream through the alveoli. Oxygen is carried by the haemoglobin found in the red blood cells and travels around the body before diffusing into a cell.

Question 5

How does carbon dioxide leave the body?

Answer 5

Carbon dioxide produced during respiration diffuses out of the cell into the blood plasma. It then travels to the lungs where it is exhaled.

Question 6

What is anaerobic respiration?

Answer 6

A type of respiration that that does not require oxygen.

Question 7

When does anaerobic respiration take place?

Answer 7

When there is not enough oxygen for aerobic respiration - e.g. during a sprint because the body requires extra energy to be produced quickly.

Question 8

What is the word equation for anaerobic respiration?

Answer 8

glucose → lactic acid (+energy)

Question 9

Why do we normally respire aerobically?

Answer 9

1. Aerobic respiration transfers more energy per glucose molecule than anaerobic respiration.
2. The lactic acid produced by anaerobic respiration can cause painful muscle cramps.

Question 10

How do plants normally respire?

Answer 10

Plants usually respire aerobically, but if the oxygen supply to the plant runs out (e.g. if the ground is waterlogged) plants switch to anaerobic respiration in their roots to obtain energy.

Question 11

Why do some microorganisms respire anaerobically?

Answer 11

It allows than to survive in environments with little to no oxygen. Over 90% of your gut bacteria perform anaerobic respiration.

Question 12

What is fermentation?

Answer 12

It is the type of anaerobic respiration in plants and microorganisms. It is a type of anaerobic respiration as the organism respires without oxygen.

Question 13

What is the word equation for fermentation?

Answer 13

glucose → ethanol + carbon dioxide (+energy)

Question 14

What is biotechnology?

Answer 14

Biotechnology is the use of biological processes or organisms to make useful products. Many of these products are foods and drinks, e.g. bread.

Question 15

What is yeast?

Answer 15

Yeast is a microorganism used in the production of bread and many alcoholic drinks. These products are made using fermentation.

Question 16

How do you make bread?

Answer 16

Flour, water and yeast are mixed to make dough, which is then left in a warm place to rise. This is caused by the yeast respiring, changing the glucose in flour into ethanol and carbon dioxide. The trapped gas is trapped as bubbles inside the dough, making it rise.

Question 17

What happens in the oven when making bread?

Answer 17

The ethanol evaporates and the carbon dioxide bubbles expand, making the bread rise further.

Question 18

How do you make beer and wine?

Answer 18

They are made in very similar ways, the type of alcoholic drink depends on the source of sugar.
Wine is made when yeast is used to ferment grape sugar, whereas beer or lager is made when yeast is used to ferment sugar in malted barley. This is known as brewing.