Section 4 - Respiration and Gas Exchange Flashcards
1
Q
How do plants exchange gases by diffusion (3)
A
- Plants photosynthesising use up CO2, so there’s hardly any inside the leaf
- Meaning more CO2 diffuses into the leaf (area of high conc to low)
- At the same time, oxygen is being made as a waste product of photosyenthesis
- Some is used up in respiration, and the rest diffuses out through the stomata (area of high conc to low conc)
2
Q
How are leaves adapted for efficent gas exchange (6)
A
- Leaves are broad, so there’s a large surface area for diffusion
- Leaves are thin, meaning gases only have to travel a short distance to reach the cells where they’re needed
- Air spaces: Let gases like carbon dioxide and oxygen move easily between cells, also increases surface area for gas exchange
- Stomata : Let gases like carbon dioxide and oxygen diffuse out, also allow water to transpire.
- Stomata close in the dark, so they don’t let carbon dioxide in, and don’t allow water to escape
- Opening and closing of the stomata is controlled by guard cells
3
Q
Describe how a human breathes in (5)
A
- Intercostal muscles contract
- diaphragm contract
- Thorax volume increases
- Decrease in pressure
- draws air in
4
Q
Describe how a human breathes out (4)
A
- Intercostal muscles and diaphragm relax
- Thorax volume decreases
- Pressure increases
- Air is forced out
5
Q
Describe an investigation of the effect of exercise on breathing rate (5)
A
- Sit still for 5 minutes, then for one minute, count the number of breaths you take
- 4 munutes of running, stop, count breathes for a minute
- Get 3 other people to do the same (compare results)
- Excercise increases breathing rate
- Control : time spent exercising, temperature, same exercise type
6
Q
Why does exercise increase your breathing rate (3)
A
- Muscles respire more during exercise
- They need to be supplied with more oxygen
- And have more carbon dioxide removed
7
Q
Explain how alveoli carry out gas exchange in the body (6)
A
- Lungs contain millions of little air sacs called alveoli, where gas exchange happens
- Blood passing next to the alveoli contains lots of carbon dioxide and little oxygen
- Oxygen diffuses out of the alveolus into the blood
- carbon dioxide diffuses out of the blood into the alvelous to be breathed out
- When the blood reaches body cells oxygen is released from red blood cells, and diffuses into body cells
- At the same time, carbon dioxide diffuses out of body cells, into blood, then carried back to the lungs
8
Q
What does blood passing next to alveoli have (2)
A
- Small amounts of oxygen
- Large amounts of carbon dioxide
9
Q
How are alveoli specialised for gas exchange (10)
A
- Millions of microscopic alveoli
- give lungs an enormous surface area
- There’s a moist lining
- for gases to dissolve in
- Thin walls, one cell thick,
- so gas doesn’t have far to diffuse
- Great blood supply,
- to maintain a high conc gradient
- Permeable walls,
- so gases can diffuse across easily.
10
Q
Explain how smocking tobacco can affect your lungs and circulatory system (5)
A
- Damages walls of the alveoli : reducing surface area for gas exchange, leading to diseases like emphysema.
- Tar in cigs damages the cilia in your lungs and trachea. Makes chest infections more likely
- Tar irritates the bronchi and bronchioles, mucus produced which cannot be ceared by damaged cilia - this causes smoker’s cough and chronic bronchitis
- Carbon monoxide reduces amount of oxygen the blood can carry. Blood pressure increases, damaging artery walls, blood clots more likely.
- Carcinogens, which are chemicals that lead to cancer
11
Q
What does smoking have/do that… (3)
a) Leads to cancer
b) Leads to smokers cough
c) Leads to emphaesyma
A
- Carcinagens
- irritates bronchi and bronchiolles
- Damages walls of the alveoli
12
Q
Word equation for anerobic respiraton in
Plants, Animals
A
Plants : glucose > ethanol + carbon dioxide (+energy)
Animals : glucose > lactic acid (+energy)
13
Q
What is respiration (2)
A
- Process of releasing energy from glucose
- Which happens constantly in every living cell
14
Q
A
