Aqa Igcse Biology. Key Facts Chapter 4

Front 1

What is moving air in and out of the lungs called?

Back 1

Breathing or ventilating them

Front 2

What happens when we breathe in?

Back 2

Intercostal muscles contract moving ribcage up and out. Muscles of the diaphragm contract and the diaphragm flattens. Volume of the thorax increases. Pressure in the thorax decreases. Air rushes into the lungs.

Front 3

What happens when we breathe out?

Back 3

Diaphragm and intercostal muscles relax. Ribcage moves down and in. Diaphragm becomes domed. Volume of the thorax decreases. Pressure in the thorax increases. Air is forced out.

Front 4

What is the movement of air in and out of the lungs called?

Back 4

Ventilation

Front 5

What gases are exchanged in the lungs?

Back 5

Oxygen is absorbed by the lungs and carbon dioxide is removed

Front 6

What do efficient exchange surfaces have?

Back 6

A large surface area, thin walls or a short diffusion distance and an efficient transport system.

Front 7

How is the surface area of the lungs increased?

Back 7

By the alveoli

Front 8

How are alveoli adapted for gas exchange?

Back 8

They have thin walls, a large surface area and a rich blood supply.

Front 9

Why are the lungs ventilated?

Back 9

To maintain a steep diffusion gradient

Front 10

Why might some people not be able to get enough oxygen into their bloodstream?

Back 10

If the alveoli are damaged the surface area for gas exchange is reduced.

if the tubes leading to the lungs are narrowed, less air can be moved through them.

If a person is paralysed, their muscles will not work to pull the ribcage up and out.

Front 11

What is the iron lung?

Back 11

A large metal machine that works as a negative pressure ventilator.

It was used for people with polio who were paralysed.

Front 12

How does the iron lung work?

Back 12

The person has to lie down in the machine and air is drawn out of the machine causing a vacuum to be formed and the patients chest to move out. This therefore causes air to enter the patient. When air is pumped back into the cylinder it creates pressure on the chest and forces the air out of the persons lungs.

Front 13

What are positive pressure ventilators?

Back 13

Breathing aids which force measured amounts of air into the lungs.

E.g bags of air linked to masks can force air down the trachea

Front 14

What are the advantages to positive pressure aids?

Back 14

They are often smaller, easier to manage in the home and can be linked to computers for control.

Front 15

Where do most chemical reactions for aerobic respiration take place?

Back 15

They take place in the mitochondria and are controlled by enzymes.

Front 16

What is the word equation for aerobic respiration?

Back 16

Glucose + oxygen --> carbon dioxide + water (+energy)

Front 17

What is the symbol equation for aerobic respiration?

Back 17

C6H12O6 + 6O2 --> 6CO2 +6H2O

Front 18

What can the energy released from respiration be used for?

Back 18

To build larger molecules from smaller ones.

Enable muscle contraction in animals.

Maintain a constant body temperature.

Active transport.

Build sugars, nitrate and other nutrients into amino acids and then proteins in plants.

Front 19

How might you investigate respiration?

Back 19

Monitor the carbon dioxide produced.

Limewater turns cloudy in the presence of carbon dioxide, the quicker it turns cloudy, the faster carbon dioxide is being produced.

Front 20

What needs to be increased during exercise for the muscles to have more energy to contract?

Back 20

Increase the rate at which oxygen and glucose reach the muscle cells.

Increase the speed at which carbon dioxide is removed.

Front 21

Doing what will allow more blood containing oxygen and glucose to reach the muscles?

Back 21

Increased heart rate and if the blood vessels supplying the muscles dilate.

Front 22

Doing what will allow a greater uptake of oxygen and release of carbon dioxide at the lungs?

Back 22

An increase in breathing rate and depth of breath

Front 23

Why is it useful during exercise that muscles sore glucose as glycogen?

Back 23

The glycogen can be converted back to glucose for use during exercise.

Front 24

What will happen if muscles done get enough oxygen?

Back 24

They will respire anaerobically

Front 25

What is anaerobic respiration?

Back 25

Respiration without oxygen.

Glucose is incompletely broken down to form lactic acid.

Front 26

What does a build up of lactic acid cause and how can it be removed?

Back 26

It caused muscle fatigue and blood flowing through the muscles removes lactic acid.

Front 27

What is the word equation for anaerobic respiration?

Back 27

Glucose --> lactic acid (+energy)

Front 28

What is the symbol equation for anaerobic respiration?

Back 28

C6H12O6 --> 2C3H6O3 (+energy)

Front 29

What is the oxygen debt?

Back 29

The extra oxygen needed after exercise to completely break down the lactic acid into carbon dioxide and water.

Front 30

What is the word equation for the breakdown of lactic acid?

Back 30

Lactic acid + oxygen --> carbon dioxide + water

Front 31

What do plant and yeast cells produce when they respire anaerobically?

Back 31

Ethanol and carbon dioxide

Front 32

What is the word equation for anaerobic respiration in plants?

Back 32

Glucose --> ethanol + carbon dioxide

Front 33

What is the symbol equation for anaerobic respiration is plants?

Back 33

C6H12O6 --> 2C2H5OH + 2CO2

Front 34

How does fitness effect the oxygen debt?

Back 34

The fitter you are the faster you can pay off your oxygen debt.