Breathing

Mouth-to-mouth resuscitation is a first aid technique. It is used when a patient has stopped breathing. The person giving the first aid exhales air into the patient's lungs through their mouth, as shown in the diagram.

What makes mouth-to-mouth resuscitation effective?

• Exhaled air contains 0% oxygen

• Exhaled air contains 0% carbon dioxide

• Exhaled air contains 16% oxygen

• Exhaled air contains 100% carbon dioxide

About 21% of the Earth's atmosphere is oxygen.

Which statement explains why oxygen is important to life on Earth?

• Oxygen is used by plants to make food

• Oxygen is used to preserve food

• Oxygen is used to release energy from food

• Oxygen is part of a balanced diet

Which statement explains why people breathe?

• It brings carbon dioxide into the lungs and removes waste oxygen from the cells

• It brings carbon dioxide into the lungs to be used by the body cells

• It brings oxygen into the lungs to be used to build up energy in food molecules

• It brings oxygen into the lungs and removes waste carbon dioxide from the body cells

• A

• B

• C

• D

• A

• B

• C

• D

Which statement is correct about about exhaled air compared with inhaled air?

• Exhaled air contains less carbon dioxide as carbon dioxide is made in the body

• Exhaled air contains less oxygen as oxygen is used in the body

• Exhaled air contains more carbon dioxide as carbon dioxide is used in the body

• Exhaled air contains more oxygen as oxygen is made in the body

Which substance is used to test for carbon dioxide?

• biuret solution

• disinfectant

• iodine solution

• limewater

Air was collected from a student as they breathed out. The air was analysed to find the percentage of each gas present.

What is gas X?

• carbon dioxide

• nitrogen

• oxygen

• water vapour

• A

• B

• C

• D

A child swallows a whole grape.

Which statement explains why swallowing a whole grape may cause death by choking?

• A grape contains a high concentration of sugar

• A grape is acidic

• A grape may be the same width as the windpipe of a child

• A grape cannot enter the stomach