7: Gas Exchange in Humans - Practical Flashcards
7.2: Examination of pig lungs
Explain the colour of the pig lungs.
The lungs are pink, because there are many capillaries in the lungs which contain blood.
7.2: Examination of pig lungs
Explain the difference in hardness between the trachea and the lung tissue.
The trachea is hard, while the lung tissue is soft and spongy. The trachea, but not the lung tissue, is supported by cartilages.
7.2: Examination of pig lungs
Explain the importance of the cartilages in the trachea. (2)
When the air pressure inside the trachea becomes too low, the trachea might collapse.
The C-shaped cartilage is to prevent the collapse of the trachea.
7.2: Examination of pig lungs
Explain what happens when the lung tissue is put in water.
The lungs tissue floats in water because the air in the air sacs of the lungs gives the lung tissue a low density.
7.4: Comparison of the oxygen content of inhaled air and exhaled air
A jar of inhaled air and a jar of exhaled air are prepared. Burning candles are lowered into the jars and the jars are closed quickly. The time that the candle burns for is recorded.
Explain how the oxygen content of inhaled and exhaled air is shown, and account for the difference. (2)
The time that the candle can burn inside the jar of exhaled air is shorter. It shows that exhaled air contains less oxygen than inhaled air.
This is because some oxygen in the inhaled air diffuses from the air sacs into the blood during gas exchange. Therefore, less oxygen is present in the exhaled air.
7.5: Comparison of the carbon dioxide content of inhaled and exhaled air
Two tubes containing hydrogencarbonate indicator are set up. Tube A has a delivery tube submerged in the indicator pointing outwards, while Tube B has a delivery tube connected to a blown mouthpiece.
Which types of air are passing through the two tubes?
Tube A: inhaled air
Tube B: exhaled air
7.5: Comparison of the carbon dioxide content of inhaled and exhaled air
Two tubes containing hydrogencarbonate indicator are set up. Tube A has a delivery tube submerged in the indicator pointing outwards, while Tube B has a delivery tube connected to a blown mouthpiece.
Explain how the carbon dioxide content of inhaled and exhaled air is shown, and account for the difference. (2)
The hydrogencarbonate indicator in tube B which exhaled air passes through turns from red to yellow, while that in tube A which inhaled air passes through remains red. It shows that exhaled air contains more carbon dioxide than inhaled air.
This is because some carbon dioxide diffuses from the blood to the air sacs during gas exchange. Therefore, more carbon dioxide is present in the exhaled air.
7.5: Comparison of the carbon dioxide content of inhaled and exhaled air
Two tubes containing hydrogencarbonate indicator are set up. Tube A has a delivery tube submerged in the indicator pointing outwards, while Tube B has a delivery tube connected to a blown mouthpiece.
Suggest a reagent that can be used to replace the hydrogencarbonate indicator, and explain the predicted results. (2)
Lime water.
The lime water in tube B turns from colourless to milky while that in tube A remains colourless.
