Gas exchange in plants Flashcards

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1
Q

What is Diffusion?

A

Movement of molecules from a region of high concentration to low concentration down a concentration gradient

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2
Q

What is the role of Diffusion?

A

Diffusion (in the alveoli) allows oxygen into the blood and carbon dioxide into the alveoli.

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3
Q

Pathway of carbon dioxide from atmosphere to chloroplasts by diffusion.

A

atmosphere → air spaces around spongy mesophyll tissue → leaf mesophyll cells → chloroplast

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4
Q

What are the adaptations of leaves to maximise gas exchange?

A
  • They are thin which gives a short diffusion distance.
  • They are flat which provides a large surface area to volume ratio.
  • They have many stomata which allow movement of gases in and out of the air spaces inside the leaf to maintain a steep concentration gradient.
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5
Q

What are the adaptations of the internal leaf structure?

A
  • Air spaces to allow gas movement around the loosely packed mesophyll cells.
  • Many stomata in the lower epidermis open in sunlight to allow gas movement in and out of the leaf.
  • Thin cell walls allow gases to move into the cells easily.
  • Moist air which gases can dissolve into for easier movement into and out of cells.
  • The close contact between the cells and the air spaces allows efficient gas exchange for photosynthesis and respiration.
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6
Q

What is the stomata?

A

Stomata are spaces found in between the guard cells on the lower epidermis of the leaf.

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7
Q

What is the role of guard cells?

A

They are responsible for the opening and closing of the stomatal pore which controls gas exchange and water loss.

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8
Q

How does the plant cell become turgid?

A

When the stomata open when water moves (by osmosis) into the guard cells. They become turgid.

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9
Q

How does the plant cell become flaccid?

A

When the stomata close when the guard cells lose water (by osmosis) to the neighbouring epidermal cells.

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10
Q

Aerobic respiration equation

A

Glucose + Oxygen -> carbon dioxide + water

C6H12O6 + 6O2 -> 6CO2 + 6H2O

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11
Q

Where does the oxygen diffuse in the leaf during respiration?

A

The oxygen diffuses down the concentration gradient from a high concentration (outside the leaf) to a low concentration (inside the leaf).

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12
Q

Where does carbon dioxide diffuse in the leaf during respiration?

A

The carbon dioxide diffuses down the concentration gradient from a high concentration (inside the leaf) to a low concentration (outside the leaf).

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13
Q

Respiration process:

A

Requires the uptake of oxygen and the release of carbon dioxide.

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14
Q

Photosynthesis process:

A

Requires the uptake of carbon dioxide and release of oxygen

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15
Q

Where does carbon dioxide diffuse in the leaf during photosynthesis?

A

carbon dioxide diffuses down the concentration gradient from a region of high concentration (outside the leaf) to a region of low concentration (inside the leaf).

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16
Q

Where does oxygen diffuse in the leaf during photosynthesis?

A

The oxygen diffuses down the concentration gradient from a high concentration (inside the leaf) to a low concentration (outside the leaf).

17
Q

What happens to the plant during the daytime?

A

The plant both respires and photosynthesize. However, the rate of photosynthesis is higher than the rate of respiration. Therefore, there is a net diffusion of carbon dioxide into the plant and net diffusion of oxygen out of the plant.

18
Q

What happens to the plant during nighttime?

A

Plant only respires, this means there is a net diffusion of oxygen into the plant and a net diffusion of carbon dioxide out of the plant.

19
Q

What happens when there is low light intensity?

A

The rate of photosynthesis is equal to the rate of respiration. This means that there is no net movement of oxygen and carbon dioxide.