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B2: Quiz 19 – Answers
B2: Quiz 19 – Answers
1) Light intensity, temperature, air flow (wind) and humidity
2) A greater light intensity increases the rate of transpiration. This is because a greater light intensity increases the rate of photosynthesis, which means that more carbon dioxide is needed in leaves. The stomata increase in size to allow more carbon dioxide to enter leaves. The stomata being open results in more water diffusing out of the leaves through the stomata. Therefore, a greater light intensity results in a greater rate of transpiration
3) A greater temperature increases the rate of transpiration. This is because a greater temperature gives the water molecules more kinetic energy, which means that the water molecules move around faster and therefore diffuse out of the stomata quicker, thus resulting in a greater rate of transpiration
4) A greater air flow means that the water that diffuses out of the leaf is blown away, which results in a low concentration of water outside the leaf. This means that there is a large difference in the concentration of water between the high concentration inside the leaf and the very low concentration outside the leaf. This high concentration gradient/ difference for water means that the rate of diffusion out of leaves is high. Therefore, a greater air flow results in a greater rate of transpiration
5)
a) Humidity measures the amount of water vapour in the atmosphere/ air; a greater humidity means that there is more water vapour in the atmosphere/ air
b) A high humidity means that there is a high concentration of water vapour outside the leaf. This means that the concentration of water molecules inside and outside the leaf are very similar (there is not much of a concentration difference/ gradient). The small concentration difference/ gradient means that the diffusion of water out of leaves will be low, thus meaning that the rate of transpiration is low. So, a greater humidity results in a lower rate of transpiration
6)
a) Small – the stomata are small at night
b) Low – the rate of transpiration is low at night
2) A greater light intensity increases the rate of transpiration. This is because a greater light intensity increases the rate of photosynthesis, which means that more carbon dioxide is needed in leaves. The stomata increase in size to allow more carbon dioxide to enter leaves. The stomata being open results in more water diffusing out of the leaves through the stomata. Therefore, a greater light intensity results in a greater rate of transpiration
3) A greater temperature increases the rate of transpiration. This is because a greater temperature gives the water molecules more kinetic energy, which means that the water molecules move around faster and therefore diffuse out of the stomata quicker, thus resulting in a greater rate of transpiration
4) A greater air flow means that the water that diffuses out of the leaf is blown away, which results in a low concentration of water outside the leaf. This means that there is a large difference in the concentration of water between the high concentration inside the leaf and the very low concentration outside the leaf. This high concentration gradient/ difference for water means that the rate of diffusion out of leaves is high. Therefore, a greater air flow results in a greater rate of transpiration
5)
a) Humidity measures the amount of water vapour in the atmosphere/ air; a greater humidity means that there is more water vapour in the atmosphere/ air
b) A high humidity means that there is a high concentration of water vapour outside the leaf. This means that the concentration of water molecules inside and outside the leaf are very similar (there is not much of a concentration difference/ gradient). The small concentration difference/ gradient means that the diffusion of water out of leaves will be low, thus meaning that the rate of transpiration is low. So, a greater humidity results in a lower rate of transpiration
6)
a) Small – the stomata are small at night
b) Low – the rate of transpiration is low at night
Questions
1) Without looking at the later questions, what are the four factors that affect the rate of transpiration.
2) Does a greater light intensity increase or decrease the rate of transpiration? Explain your answer.
3) Does a greater temperature increase or decrease the rate of transpiration? Explain your answer.
4) Does an increase in air flow around a plant increase or decrease the rate of transpiration? Explain your answer.
5)
a) What is humidity?
b) Does a greater humidity in the air around a plant increase or decrease the rate of transpiration? Explain your answer.
6)
a) Are the stomata big or small at night?
b) Is the rate of transpiration high or low at night?
1) Without looking at the later questions, what are the four factors that affect the rate of transpiration.
2) Does a greater light intensity increase or decrease the rate of transpiration? Explain your answer.
3) Does a greater temperature increase or decrease the rate of transpiration? Explain your answer.
4) Does an increase in air flow around a plant increase or decrease the rate of transpiration? Explain your answer.
5)
a) What is humidity?
b) Does a greater humidity in the air around a plant increase or decrease the rate of transpiration? Explain your answer.
6)
a) Are the stomata big or small at night?
b) Is the rate of transpiration high or low at night?