All of the following involve active transport across membranes except... a-- the
ID: 35927 • Letter: A
Question
All of the following involve active transport across membranes except...
a-- the movement of sugar from low concentration to high concentration.
b- the movement of sugar from one sieve-tube element to the next.
c- the movement of K+ across guard cell membranes during stomatal opening.
d- the movement of mineral nutrients from soil water or the apoplast into cells of the root cortex.
2 In vascular plants, how is the sucrose-rich phloem sap transported?
From the roots to the leaves
From the leaves to the roots
From sucrose source to sucrose sink
Only diffuses locally
QUESTION 3
Stomates open when...
a- Potassium ions flow into the guard cells through ion channels, lowering the solute potential in the cells, such that they take in water via osmosis and become turgid.
b- Potassium ions flow into the guard cells through ion channels, raising the solute potential in the cells, such that they take in water via osmosis and become turgid.
c- Potassium ions flow out of the guard cells through ion channels, lowering the solute potential in the cells, such that they take in water via osmosis and become turgid.
d- Potassium ions flow out of the guard cells through ion channels, raising the solute potential in the cells, such that they take in water via osmosis and become turgid.
QUESTION 4 (MORE THAN ONE ANSWER CAN BE CHOSEN)
Which of the following are plausible pathways for a C atom in a sugar produced via photosynthesis? (You may pick more than one answer)
It ends up in an ADP molecule.
It ends up in a CO2 molecule released from the root of the plant.
It is lost via transpiration from the leaf.
It ends up in a chlorophyll molecule in the leaf.
a-- the movement of sugar from low concentration to high concentration.
b- the movement of sugar from one sieve-tube element to the next.
c- the movement of K+ across guard cell membranes during stomatal opening.
d- the movement of mineral nutrients from soil water or the apoplast into cells of the root cortex.
Explanation / Answer
b. the movement of sugar from one sieve-tube element to the next.
c. From sucrose source to sucrose sink.
b. Potassium ions flow into the guard cells through ion channels, raising the solute potential in the cells, such that they take in water via osmosis and become turgid.
b. It ends up in a CO2 molecule released from the root of the plant.
b. Leaf of the low-light treated plant has higher respiration and lower maximum photosynthesis rates.
6. Compensation point is the light intensity on the photosynthetic curve when the rate of photosynthesis is same as that of respitration. Thereby the amount of carbondioxide released during respiration and oxygen released during photosynthesis is balanced in a plant.
An understory ephemeral plant in a hardwood, deciduous forest, would have higher light compensation point in spring compared to an understory plant that emerges later in the summer.
The intensity of light to which the understory plant is exposed is more (leaves of tall trees are shredded) thereby increasing the rate of photosynthesis than respiration. Whereas during summer the understory plant is exposed is less intensity of light (leaves of tall trees form a thick canpoy) reducing the rate of photosynthesis. Hence the compensation point would be lower.
b. the movement of sugar from one sieve-tube element to the next.
c. From sucrose source to sucrose sink.
b. Potassium ions flow into the guard cells through ion channels, raising the solute potential in the cells, such that they take in water via osmosis and become turgid.
b. It ends up in a CO2 molecule released from the root of the plant.
b. Leaf of the low-light treated plant has higher respiration and lower maximum photosynthesis rates.
6. Compensation point is the light intensity on the photosynthetic curve when the rate of photosynthesis is same as that of respitration. Thereby the amount of carbondioxide released during respiration and oxygen released during photosynthesis is balanced in a plant.
An understory ephemeral plant in a hardwood, deciduous forest, would have higher light compensation point in spring compared to an understory plant that emerges later in the summer.
The intensity of light to which the understory plant is exposed is more (leaves of tall trees are shredded) thereby increasing the rate of photosynthesis than respiration. Whereas during summer the understory plant is exposed is less intensity of light (leaves of tall trees form a thick canpoy) reducing the rate of photosynthesis. Hence the compensation point would be lower.
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