8.1 + 8.2

Question 1

List the features of gas exchange surfaces in humans

Answer 1

1. large surface area
2. thin surface
3. good blood supply
4. good ventilation with air
5. moist

Question 2

Explain the differences in composition between inspired and expired air

Answer 2

Inspired gas: the gas we take in during breathing, contains mostly oxygen

(expired gas is the gas we breathe out which is mostly carbon dioxide)

inspired gas: contains less carbon dioxide

(expired gas contains less oxygen)

Question 3

Explain the effects of physical activity on rate and depth of breathing

Answer 3

the increased carbon dioxide concentration in the blood causes an increased rate of breathing

BECAUSE

During exercise there is an increase in physical activity. So, muscle cells respire more than they do when the body is at rest. The heart rate increases during exercise.
The rate and depth of breathing increases to make sure that oxygen is absorbed into the blood, and more carbon dioxide is removed from it

Question 4

Explain the role of goblet cells, mucus and ciliated cells

Answer 4

They are for protecting the gas exchange system from pathogens and particles. Both in the epithelial lining.

Goblet cells: makes sticky, slimy mucus
(so bacteria in the air and dust particles get trapped in the mucus)

Ciliated cells: have tiny, microscopic hair on them called cilia
(cilia beat in unison, and sweep the mucus upwards, towards the back of the throat)

Question 5

State the diseases caused by tobacco smoking

Answer 5

Chronic obstructive pulmonary disease
Lung cancer
Coronary heart disease

Question 6

Describe the effects on the gas exchange system of tobacco smoke + its major toxic components

Answer 6

Toxic components: carbon Monoxide, nicotine, tar

Tar:
- causes more mucus to be produced
- paralyses cilia cells (so they can’t remove the mucus)
- SO, mucus builds up in our airways (which is why smokers cough more)
- Clogs up the alveoli (which reduces surface area, so less oxygen can enter)

Nicotine:
- raises heart bpm
- Increases blood pressure by narrowing our blood vessels
- addictive

Carbon monoxide:
- Binds with the haemoglobin, reducing its ability to carry oxygen
- SO, it puts more strain on our respiratory system

Question 7

Name and identify the
1. lungs
2. diaphragm
3. ribs
4. intercostal muscles
5. larynx
6. trachea
7. bronchi
8. bronchioles
9. alveoli
10. associated capillaries

Answer 7

see diagram

Question 8

State the differences in composition between inspired and expired air
(oxygen, carbon dioxide + water vapour + Nitrogen)

Answer 8

Nitrogen:
Inspired = 79%
Expired = 79%
reason: same because it is not used/ produced by body processes

Oxygen:
Inspired = 21%
Expired = 16%
reason: decreases because it is used up in respiration

Carbon dioxide:
Inspired = 0.04%
Expired = 4%
reason: increases because it is produced in respiration

Water vapour:
Inspired = variable
Expired: Saturated
reason: produced by respiration and moisture evaporates from surface of alveoli

Question 9

How is lime water used as a test for carbon dioxide to investigate the differences in composition between inspired and expired air

Answer 9

We use limewater because it changes colour when the gas is bubbled through. It goes from colourless to milky.

There is more CO2 present in expired air, so it makes limewater change colour more quickly (than inspired air).

Question 10

Investigate and describe the effects of physical activity on rate and depth of breathing

Answer 10

When you exercise, your muscles work harder and your body uses more oxygen and produces more carbon dioxide.

To cope with this extra demand, your breathing has to increase from about 15 times a minute (when you are resting), up to about 40–60 times a minute during exercise.

Breathing rate and depth increase to absorb more oxygen for the muscles as exercising muscles need to respire more to get more energy.

Anaerobic: We need to breathe more to pay back the oxygen debt and break down the lactic acid

Question 11

Uses of energy in the body of humans

Answer 11

• muscle contraction
• protein synthesis
• cell division
• growth and the maintenance of constant body temperature

Question 12

State the word equation for aerobic respiration

Answer 12

glucose + oxygen → carbon dioxide + water

Question 13

Define aerobic respiration

Answer 13

aerobic respiration: the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

Question 14

State the balanced chemical equation for aerobic respiration

Answer 14

C(6)H(12)O(6) + 6O(2) → 6CO(2) + 6H(2)O
look in the textbook (cause it has subtext and exponents I can’t enter here)

Question 15

Define anaerobic respiration

Answer 15

anaerobic respiration: the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen

Question 16

State the word equation for anaerobic respiration in muscles during vigorous exercise

Answer 16

glucose → lactic acid

Question 17

lactic acid?

Answer 17

lactic acid builds up in muscles and blood during vigorous exercise causing an oxygen debt

Question 18

State the word equation for anaerobic respiration in microorganism yeast

Answer 18

anaerobic respiration:
glucose → alcohol + carbon dioxide

Question 19

Describe the role of anaerobic respiration in yeast during bread-making

Answer 19

In bread-making, sugar is used as a source of glucose. Through anaerobic respiration, the bread respires, producing carbon dioxide. This causes the bread to rise.

Question 20

anaerobic vs aerobic

Answer 20

anaerobic respiration releases much
less energy per glucose molecule than aerobic respiration

both use glucose as a reactant

aerobic takes place in the mitochondria, anaerobic in the cytoplasm