Section 4 Respiration And Gas Exchange in Humans and Plants

Question 0

What is respiration?

Answer 0

The process of releasing energy from glucose into living organisms.

Question 1

Which type of respiration is most efficient and why?

Answer 1

Aerobic respiration.

It produces more energy.

Question 2

What is the equation for aerobic respiration?

Answer 2

Glucose + oxygen ➡️ carbon dioxide + water (+ energy)

Question 3

When is anaerobic respiration used?

Answer 3

When there isn’t enough oxygen.

Question 4

What is the equation for anaerobic respiration in plants?

Answer 4

Glucose ………… Ethanol + carbon dioxide (+ energy)

Question 5

What is the equation for anaerobic respiration in humans?

Answer 5

Glucose ………. Lactic acid (+ energy)

Question 6

What diffuses in photosynthesis?

Answer 6

CO2 in

O2 out

Question 7

What happens when plants respire at night?

Answer 7

Take in oxygen and release CO2

Question 8

How is a leaf adapted for gas exchange?

Answer 8

Large surface area for diffusion
Thin, short distance for gases to travel
Air spaces inside increases surface area for gas exchange
Guard cells control the opening of stomata, close them in dark so water can’t escape and plant doesn’t dry out
Stomata allow gases to diffuse in and out

Question 9

What is the top part of the body called and describe the structure of it.

Answer 9

Thorax.

It includes:
The ribs
Intercostal muscles
Diaphragm
Trachea
Bronchi
Bronchioles
Alveoli
Pleural membranes.

Question 10

What are the lungs protected by?

Answer 10

Ribcage

Plural membranes

Question 11

Where does gas exchange take place?

Answer 11

The alveoli

Question 12

What happens when you breath in?

Answer 12

Intercostal muscles and diaphragm contract
Thorax volume increase
Decrease pressure.

Question 13

What happens when you breath out?

Answer 13

Intercostal muscles and diaphragm relax
Thorax volume decreased
Air is forced out.

Question 14

How can you investigate the effect of exercise on breathing rate?

Answer 14

Count resting breathing rate (no of breaths you take) for one minute
One breath in and one breath out = one breath
Do five mins of exercise e.g. Running
Count breathing rate again in one min as soon as you stop
Repeat with two other people to compare results
Should find exercise increases breathing rate

Question 15

What diffuses in and out of the alveolus?

Answer 15

Oxygen - out

CO2 - in

Question 16

What happens when the blood reaches body cells?

Answer 16

Oxygen diffuses in

CO2 diffuses out and carried back to the lungs

Question 17

Why is the alveoli good for gas exchange?

Answer 17

Large Surface area
Moist lining for gases to dissolve in
Thin walls so not far for gases to diffuse
Great Blood supply to maintain a high concentration gradient
Permeable walls for easy diffusion

Question 18

How does smoking tabaco affect gas exchange in the lungs and the circulatory system?

Answer 18

Affects lungs 
Damages alveoli, reduces surface area
Tar damages cilia 
Tar irritates the bronchi
Carbon monoxide reduces oxygen
Chemicals lead to cancer of lungs / mouth / throat

Nicotine increases heart rate and blood pressure
Nicotine makes blood vessels narrower, can lead to heart disease.
Carbon monoxide takes place of oxygen in red blood cells, this reduces amount of oxygen the blood can carry.
So circulatory system has to work harder, causing heart disease.

Question 19

How can respiration be investigated using the production of carbon dioxide?

Answer 19

1.soak some dried beans in water - start to germinate/germinating beans will respire
2.boil a second bunch of beans- kill the beans so they can’t respire
3.put some hydrogen-carbon indicator in the two test tubes
4.place a gauze platform into each test tube with the beans on top and seal with a rubber bung
5. Leave for a set time
CO2 will turn the indicator yellow- respiration

Question 20

How can respiration be measure using the heat?

Answer 20

1. prepare one set of beans by drying and soaking them to germinate, and the others by boiling to kill them
2. Add each set to a vacuum flask with some air
3. Place a thermometer into each flask with cotton wool
4. Record the temperature daily for a week
5. They will respire and produce heat only in the test flask (germinating living beans)

Question 21

When does photosynthesis happen?

Answer 21

During the day

Question 22

how does hydrogen-carbonate indicator show CO2 concentration?

Answer 22

In air - orange
More CO2 - becomes more yellow
Less CO2 - purple

Question 23

How can you show differences in net gas exchange in plants?

Answer 23

1.add the same volume of hydrogen-carbonate to four test tubes
2.put leaves into three test tubes and seal with a rubber bung, trap the stem with the bung so it doesn’t fall in the indicator
3. Completely wrap one in aluminium foil and one in gauze
4. Leave in bright light for an hour then check the colour of the indicators
Results- no change to the control, more wrapped up more CO2 concentration

Question 24

What are the differences between aerobic and anaerobic respiration?

Answer 24

Aerobic respiration produces more energy.

Oxygen is used in aerobic respiration but isn’t in anaerobic respiration.

Aerobic respiration produces carbon dioxide and water giving energy (ATP), but anaerobic respiration produces a build up of lactic acid giving energy (ATP).

Question 25

What is the role of diffusion in gas exchange in humans?

Answer 25

Diffusion: The gases move by diffusion from where they have a high concentration to where they have a low concentration.

So: Oxygen diffuses from the air in the alveoli (high) into the blood (low).
Carbon dioxide diffuses from the blood (high) into the air in the alveoli (low).

Question 26

What is the role of diffusion in gas exchange in plants?

Answer 26

Diffusion: the gases move by diffusion from where they have a high concentration to where they have a low concentration.

So: in photosynthesis, CO2 diffuses from the atmosphere (high concentration) into the plant (low concentration) and O2 diffuses out of the plant (high concentration) into the atmosphere (low concentration).

Question 27

Respiration occurs during the….. But the net exchange of carbon dioxide and oxygen (photosynthesis) depends on the….. So only occurs in the day.

Answer 27

Day and night

Light intensity.

Question 28

What is the role of the stomata in gas exchange?

Answer 28

Let gases diffuse in and out of the leaf
Allow water to escape e.g. Transpiration
Close when dark, water can’t escape, so stops plant drying out.