Topic1.5 - Breathing & Respiratory System

Question 1

Word equation for respiration

Answer 1

Oxygen + glucose -> carbon dioxide + water + energy

Question 2

Chemical equation for respiration

Answer 2

6O(2) + C(6)H(12)O(6) -> 6CO(2) + 6H(2)O + energy

Question 3

Uses of energy

Answer 3

Provides heat (e.g. maintaining human body temp 37^C)

Allows movement (e.g. muscle contraction)

Growth

Reproduction

Process of active transport (use by plants to absorb minerals from the soil) - energy needed to move molecules against the concentration gradient.

Question 4

Nasal cavity role

Answer 4

Contains many ciliated cells used to trap germs (filter air) and the presence of many blood vessels with good blood supply warms the inhaled air

Question 5

Trachea role

Answer 5

Carries air to lungs, held open by ‘c’ shaped rings of cartilage as the oesophagus is situated behind it. The walls are coated in sticky mucus (produced by goblet cells) that catches any germs that may have been inhaled.

Question 6

Bronchioles role

Answer 6

Smaller air tubes that form from branches off the bronchi - ensure air is delivered to all parts of the lungs

Question 7

Alveoli role

Answer 7

Microscopic air sacs found at the end of the bronchioles. They are the sites of gas exchange (oxygen enters the blood, CO(2) leaves the blood). The surface is only 1 cell thick and surrounded by many capillaries.

Question 8

Diaphragm role

Answer 8

Large sheet of muscle that has the ability to contract and relax, altering the volume in the thorax.

Question 9

Ribs role

Answer 9

Form a rigid protective cage around the lungs and other organs. Moved by the intercostal muscles during the breathing, causing volume and pressure changes in the thorax

Question 10

Pleural membranes and fluid role

Answer 10

They ensure that friction is minimised during breathing

Question 11

Inhaling process

Answer 11

Diaphragm contracts and flattens
Intercostal muscles contract, raising the rib cage
Volume of thorax increases
Pressure in thorax decreases
Air rushes in filling the lungs

Question 12

Exhaling process

Answer 12

Diaphragm relaxes and returns to domed position
Intercostal muscles relax, the rib cage falls down and in
Volume of thorax decreases
Pressure in thorax increases
Air is forced out

Question 13

Inhaled air vs exhaled air
Oxygen
Carbon dioxide 
Nitrogen 
Water vapour
Temperature

Answer 13

Inhaled air
(Oxygen) 21%
(Carbon dioxide) 0.04%
(Nitrogen) 79%
(Water vapour) variable 
(Temperature) variable

Exhaled air
(Oxygen) 16%
(Carbon dioxide) 4%
(Nitrogen) 79%
(Water vapour) always higher 
(Temperature) always higher

Question 14

Limewater before and after CO(2)

Answer 14

Clear -> cloudy

Question 15

Bicarbonate indicator before and after CO(2)

Answer 15

Red/orange -> orange/yellow

Question 16

Adaptations of gas exchange surfaces

Answer 16

Surfaces should be thin to allow gases to diffuse across them quickly - the walls of the alveoli are one cell thick

They should have mechanisms to maintain a steep concentration gradient - the constant flow of blood and breathing in + out maintains the gradient between the blood and the air

They should be moist - the alveoli are coated in a layer of moisture that the gases dissolve into

They should have a large SA - the alveoli provide a large SA (about the size of a tennis court in each lung)

Question 17

2 adaptations of the red blood cell for carrying oxygen

Answer 17

Large SA (biconcave)

No nucleus therefore more space for haemoglobin

Question 18

Aerobic vs anaerobic

Answer 18

Aerobic = in the presence of oxygen

Anaerobic = in the absence of oxygen

Question 19

Anaerobic respiration in human cells equation

Answer 19

C(6)H(12)O(6) -> 2C(3)H(5)OH + 150 kJ

Glucose -> lactate + energy

Question 20

Anaerobic respiration in yeast equation

Answer 20

C(6)H(12)O(6) -> 2C(2)H(5)OH + 2CO(2) + 210 kJ

Glucose -> ethanol + carbon dioxide + energy

Question 21

Differences between aerobic and anaerobic respiration

Answer 21

Less energy produced (in anaerobic respiration, the glucose molecule isn’t fully broken down)

Oxygen isn’t used in anaerobic respiration

Lactic acid and ethanol are produced in anaerobic respiration

Question 22

Anaerobic respiration in humans description

Answer 22

Strenuous rapid exercise increases the amount of oxygen needed by the muscles

Eventually the breathing rate cannot meet the oxygen demand and so muscle cells begin to respire anaerobically

The lactic acid produced is a mild poison and causes pain

That’s break down the lactic acid oxygen is needed - this is the oxygen debt

Question 23

Uses of yeast and anaerobic respiration

Answer 23

Manufacture of alcoholic drinks e.g. beer. Barley grains contain malted sugar - this is crushed and combined with hops (for flavour). The sugar is then gradually converted to alcohol by the yeast.

Bread making. Yeast, sugar, flour and water are combined to form dough that is left to prove in a warm place. The proving time allows the CO(2) bubbles to form in the dough. Afterwards, the bread is baked in the oven - this evaporates the alcohol and kills the yeast

Question 24

(Practical) why is the paraffin added?

Answer 24

To prevent oxygen from getting into the yeast and boiled water solution through the tube

Question 25

(Practical) why is it important to boil the water?

Answer 25

To remove any dissolved oxygen

Question 26

(Practical) why must the sugar solution be cooled before adding the yeast?

Answer 26

A very high temperature would kill the yeast cells