Respiration and Gas Exchange

Question 1

What is respiration

Answer 1

The process from which energy is released

Question 2

Chemical and word equation for aerobic respiration

Answer 2

Glucose + oxygen–> carbon dioxide + water + energy (ATP)

C6H12O6 + 6O2–> 6CO2 + 6H2O + energy

Question 3

Word equation for anaerobic reparation in animals

Answer 3

Glucose–> lactic acid + energy + energy

Question 4

Word equation for anaerobic reparation in plants

Answer 4

Glucose–> ethanol + carbon dioxide + energy

Question 5

Experiment to see that heat and carbon dioxide are wast products of respiration

Answer 5

Bubble gas released through limewater
= goes milky if CO2

Record temperature before experiment and after= there will be a rise.

Question 6

Role of diffusion in gas exchange

Answer 6

Oxygen enters the blood and carbon dioxide leaves the blood.
Gases diffuse across the walls of the alveoli.

• Oxygen goes into the blood as there is a lower concentration in the blood
• Carbon dioxide diffuses into the lungs as there is a lower conc of it In the lungs

Question 7

Gas exchange in plants

Answer 7

Photosynthesis= co2 taken in and o2 given out.

Respiration= o2 taken in, co2 given out.

Question 8

What does the overall amount of CO2 and O2 depend on?

Answer 8

Light intensity.

Question 9

How is the structure of a leaf adapted to gas exchange?

Answer 9

Spongy mesophyll= internal air spaces increase surface area for the leaf to absorb more CO2. Loosely packed and are covered by a thin film of water.

Guard cells around the stomata= guard cells open and close stoma depending on how much water there is (turgid or flaccid)

Question 10

How does stoma control gas exchange in the leaf

Answer 10

In the light, water is taken in by osmosis for photosynthesis making the plant turgid. This opens stoma and allows gas exchange to occur.

At night= water is not taken in as photosynthesis cannot occur, so plant becomes flaccid. This closes the stoma.

Question 11

How can you carry out an experiment to see the effect of light on gas exchange?

Answer 11

1) place a pond weed in water with hydrogen carbonate indicator (og orange)
2) have a lamp at set distances (close= high light intensity and far away= low light intensity)
3) repeat at different distances
Indicator is yellow when there is a lot of CO2= high light intensity,
Purple when there is little CO2= low light intensity.

Question 12

What happens when we breathe in?

Answer 12

Intercostal muscles contract
Diaphragm contracts and moves down.
Volume of thorax increases and rib age moves up and out
pressure decreases=Air sucked in.

Question 13

What happens when we breathe out

Answer 13

Intercostal muscles relax
Diaphragm relaxes and moves in
Ribcage moves in and down and thorax volume decreases
Pressure increases, air is pushed out.

Question 14

Adaptations of alveoli

Answer 14

Folded= large surface area for gas exchange to occur 
Thickness= alveoli walls are one cell thin= short diffusion distance.
Capillaries= rich blood supply maintains conc. gradient. 
Ventilated= each alveolus is well ventilated so co2 is removed and O2 levels are replenished= high conc. gradient.

Question 15

Effects of smoking on the lungs

Answer 15

Cigarettes contain harmful chemicals
E.,g nicotine= addictive drug
Carbon monoxide= poisonous.

Question 16

How does smoking affect air passages ?

Answer 16

Cigarette smoke damages cilia hairs so they cannot sweep out the mucus with trapped pathogens. To get rid of it, smokers cough a lot and this damages the walls of the alveoli= bronchitis

Question 17

Effect of smoking on alveoli

Answer 17

Smoke damages the walls of the alveoli causing them to break down and join together= large gaps= small surface area (emphysema)
This reduces efficiency of gas exchange so oxygen levels in blood are low= exercise is difficult.

Question 18

Effects of smoking in terms of carbon monoxide?

Answer 18

Incomplete combustion from cigarette smoke= CO

Combines with haemoglobin in red blood cells= reduces the blood’s oxygen carry capacity= strain on circulatory system and an increased risk of coronary heart disease and strokes.

Question 19

How does smoking cause lung cancer

Answer 19

Tobacco smoke contains many carcinogens, including tar which increases the risk of mouth, Throat and lung cancer.

Question 20

Effect of exercise in breathing?

Answer 20

1) Count breath in 10 seconds from a stationary person and multiply by 6 to get results for one minute.
2) repeat again, but after doing exercise.
Plot results on graph= overall trend is that breathing rate increase as intensity of exercise increases too.