Gaseous Exchange, Thorax, Ventilation, Smoking

Question 1

Describe the role of stomata in gas exchange during the day

Answer 1

1. Guard cells will photosynthesise, making glucose and the water concentration of cells lower.
2. Therefore osmosis they will absorb H2O by osmosis and become turgid.
3. thin outer wall will curve more than inner leading to stomata to open.
4. Gaseous exchange happens

Question 2

Describe the role of stomata in gas exchange during the night

Answer 2

1. Guard cells will not photosynthesise, and use up glucose so the water concentration of cells will increase.
2. Therefore will lose water by osmosis and they will become flaccid.
3. thin outer wall will straighten more than inner leading to stomata to close.
4. Gaseous exchange does not occur.

Question 3

What does the overall exchange of gas depend on.

Answer 3

time of day and light intensity.

Question 4

What happens when there is no photosynthesis happening. ( during night when there is no light)

Answer 4

When there is no photosynthesis, there is a net release of carbon dioxide and a net uptake of oxygen (remember respiration is always occurring as it is not reliant on light). carbon dioxide will not be taken in by photosynthesising cells in plants and oxygen will not be produced as a waste product. O2 will be used in respiration, as a result more carbon dioxide will be released and more oxygen will be taken up.

Question 5

What happens when there is photosynthesis happening. ( during day when light is present)

Answer 5

If there is light there is photosynthesis, therefore :the rate of photosynthesis is higher than the rate of respiration and there is a net release of oxygen and a net uptake of carbon dioxide. carbon dioxide will be taken in by photosynthesizing cells in plants and oxygen will be produced as a waste product. So more oxygen will be released and more carbon dioxide will be taken up

Question 6

What does hydrocarbonate indicate and what colour changes occur.

Answer 6

Yellow = CO2 concentration is high
Red = CO2 concentration atmospheric level(low)
Purple = CO2 concentration lowest

Question 7

investigate the effect of light on net gas exchange from a leaf and the results.

Answer 7

1. Take 3 beakers of same size and add 20ml of hydrogen carbonate indicator and add a leave to each.
2. take another beaker as a control but put no leave in it.
3. Wrap aluminium foil around one allowing no light through, one in muslin allowing little and last to be be completely exposed to light.
4. Now shine bright light onto them for 45 minutes.
   *the results.
   The one with aluminium foil would have turned yellow as CO2 concentration in the water increases because the rate of respiration is higher than the rate of photosynthesis
   The one completely exposed would have turned purple as the CO2 concentration in the water decreases because the rate of photosynthesis is greater than the rate of respiration
   The one in with muslin would have stayed the same colour as it would be doing equal amount of photosynthesis and respiration.

Question 8

Description of ribs

Answer 8

Bone structures that protect internal organs such as the lungs

Question 9

Description of intercostal muscles.

Answer 9

Muscles between the ribs controlling their movement causing inhalation and exhalation.

Question 10

Description of diaphragm

Answer 10

Sheet of connective tissue and muscle bottom of the thorax that helps change volume of thorax to help inhalation and exhalation

Question 11

Description of trachea

Answer 11

Windpipe that connects mouth and nose to the lungs.

Question 12

Description of Bronchi (pl)

Answer 12

Large tubes branching off the trachea with one bronchus (sin) to each lung

Question 13

Description of Bronchioles

Answer 13

Bronchi split to form smaller tube ( Bronchioles ) in lungs connected to alveoli

Question 14

Description of Alveoli

Answer 14

Tiny air sacs where gaseous exchange takes place

Question 15

Description of pleural membranes

Answer 15

Stick outside lungs inside of chest cavity so lungs follow chest movement, lubricates lungs to reduce friction

Question 16

what is the role of the intercostal muscles and the diaphragm in ventilation during inhalation

Answer 16

1. External inter coastal muscles contract.
2. Internal inter coastal muscles relax.
3. Ribs move up and out
4. Diaphragm contracts + flattens
5. Volume of thorax increases
6. Pressure inside thorax decreases
7. Air is drawn into the lungs

Question 17

what is the role of the intercostal muscles and the diaphragm in ventilation during Exhalation

Answer 17

1. External inter coastal muscles relax.
2. Internal inter coastal muscles contract.
3. Ribs move inward and down
4. Diaphragm relaxes and curves.
5. Volume of thorax decreases
6. Pressure inside thorax increases
7. Air is forced out of the lungs

Question 18

Explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries

Answer 18

• The alveoli are the gas exchange surface of the lungs
  1. Large surface area to allow faster diffusion of gases across the surface
  2. Thin walls to ensure diffusion distances remain short
  3. Moist surface so that gases can dissolve and diffuse across easily
  4. Good blood supply to maintain a high concentration gradient so diffusion occurs faster
  5. Permeable to gases

Question 19

what are the biological consequences of smoking

Answer 19

Smoking causes lung disease, heart disease and increased risks of several different types of cancer

Question 20

What are the chemicals involved in cigarettes and their impact

Answer 20

Tar – a carcinogen (a substance that causes cancer))
Nicotine – an addictive substance which also narrows blood vessels
Carbon monoxide – reduces the oxygen carrying capacity of the blood

Question 21

Effect of smoking on air passage

Answer 21

1. Tar destroys cilia which carry dust and microbes trapped by mucus away from the lungs.
2. This results to build of mucus and potentially leading to bronchitis as the lining of the bronchi become irritated

Question 22

Effect of smoking on alveoli

Answer 22

1. Breaks down alveoli resulting them in merging.
2. This creates insufficient surface area to volume ratio, allowing less gas exchange therefore educes the efficiency of gas exchange.
3. This is known as emphysema where less oxygen is carried in blood.

Question 23

Effects of smoking on the circulatory system.

Answer 23

1. Nicotine narrows blood vessels so will put more strain on the circulatory system and increase blood pressure
2. Narrow blood vessels are more likely to be clogged with fat including cholestrol.
3. If this happens in the coronary artery it causes coronary heart disease.
4. this will result in heart cells not receiving sufficient oxygen therefore respire anaerobically, producing lactic acid which cannot be removed (due to lack of blood supply) .
5. This results in creating a low pH environment in cells causing enzymes to denature and eventually heart muscle cells will die.
6. This could cause a heart attack.

Question 24

What does carbon monoxide do to blood and what risks does it cause.

Answer 24

1. Carbon monoxide binds irreversibly to haemoglobin, reducing the capacity of blood to carry oxygen
2. Resulting in more strain on circulatory system also increasing the risk of coronary heart disease and strokes.

Question 25

Investigating the release of carbon dioxide when breathing out

Answer 25

1. Add lime water to a boiling tube
2. Use a straw and blow into the solution of lime water for a short period of time
3. Limewater turns milky white (cloudy) when carbon dioxide is present
   * This shows carbon dioxide is present in the air we breathe out

Question 26

Investigating the effect of exercise on breathing and explain reasons for the causes.

Answer 26

*Exercise increases the frequency and depth of breathing
1. Exercise for 3 sets for 3 minutes (same exercise).
2. Immediately after exercising, count the breaths taken in one minute and measure the average chest expansion over 5 breaths.
* After exercise the number of breaths and chest expansion should have increased.
This means muscles are working harder therefore increasing the demand of oxygen and removal of CO2 (increase of breathing rate) .
If oxygen isn’t sufficient the muscles will start respiring anaerobically making lactic acid.
* This can be seen by checking how long the breathing rate takes to get back to normal, the longer the more lactic acid produced.