Week 14 L6: Abiotic Environment - Water Stress - Stoma Closure Flashcards

1
Q

Where are the receptors for ABA found?

A

stomata/stoma

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2
Q

What are the receptors called that ABA bind to?

A

pyrabactin-like proteins

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3
Q

What is pyrabactin?

A

synthetic sulfonamide which is a synthetic agonist for ABA.

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4
Q

What does ABA to pyrabactin-like channels cause?

A

Causes a signalling mechanism which activates calcium channels, which brings Calcium from outside and calcium stored in the vacuole into the cytoplasm.

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5
Q

Calcium moves into the cytoplasm but where does it cone from?

A

vacuoles and outside the cell via Ca2+ channels

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6
Q

What happens to intracellular calcium conc upon Ca2+ channels opening?

A

elevated conc

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7
Q

What happens when Ca2+ levels are elevated in the cell?

A

inhibits proton pumps. so H+ remains inside the cell.

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8
Q

What is the effect when proton pumps are inhibited?

A

increase H+ conc in the cell. increase acidity, lower pH

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9
Q

What happens when the cell becomes more acidic?

A

K+ channels are blocked.

So no K+ will enter the cell.

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10
Q

What happens simultaneously to K+ channels pumping K+ into cell being blocked?

A

K+ channel which pump K+ out of the cell are activated

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11
Q

What does the Ca2+ in the cytoplasm lead to?

A

H+ pump being inhibited, decrease pH and block K+ coming into the cell
It directly activates K+ channels which pumps K+ out of the cell.

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12
Q

What accumulates outside the cell?

A

K+ and water leaves the guard cell.

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13
Q

Why does water move outside the cell?

A

Due to a drop in water potential outside the cell

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14
Q

When does the guard cell close?

A

When water leaves the cell

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15
Q

What are the rigidified part of the guard cells?

A

lips

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16
Q

What part of the guard cell does not stretch and why?

A

the lips as they are rigid and non-elastic

17
Q

What is the main control of water loss in leaves?

A

stomata