Plant Gaseous Exchange and Stomata

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Questions and Answers

What is primarily exchanged through the stomata in plants?

Oxygen and carbon dioxide (correct)

Water and light

Sodium and potassium

Nutrients and minerals

Where are stomata predominantly located in plants?

On the stems

On the lower epidermis of the leaf (correct)

In the roots

On the upper epidermis of the leaf

What role do guard cells play in the functioning of stomata?

They conduct photosynthesis

They control the opening and closing of the stoma (correct)

They synthesize chlorophyll

They absorb nutrients

What happens to guard cells when they become turgid?

They curve outwards, opening the stoma (D) Signup and view all the answers

Which of the following correctly describes the influence of potassium ions on guard cells?

They facilitate the uptake of water into guard cells (A) Signup and view all the answers

During which condition do guard cells convert sugar into starch?

At night or in the absence of light (A) Signup and view all the answers

What triggers the closing of stomata?

The movement of potassium ions out of the guard cells (A) Signup and view all the answers

What is the primary function of stomata in plants?

To facilitate photosynthesis and respiration (B) Signup and view all the answers

How do guard cells change their shape to open or close the stomata?

Through osmosis of water in and out of the cells (A) Signup and view all the answers

What effect does light have on the sucrose concentration in guard cells?

Increases sucrose concentration (A) Signup and view all the answers

What occurs in guard cells during nighttime?

Sugar converts to starch (B) Signup and view all the answers

What happens to the water potential in guard cells when potassium ions are taken up?

It decreases and the guard cells become turgid (B) Signup and view all the answers

What primarily determines whether guard cells are turgid or flaccid?

The potassium ion uptake and sucrose concentration (A) Signup and view all the answers

How does the process of osmosis affect guard cells during stomatal opening?

Osmosis causes water to diffuse in, increasing turgidity (C) Signup and view all the answers

What ionic change occurs in guard cells during the opening of stomata?

Potassium ions enter the cells (C) Signup and view all the answers

Which of the following statements accurately describes the relationship between stomata and photosynthesis?

Stomata help in gas exchange, which is necessary for photosynthesis (B) Signup and view all the answers

Study Notes

Plant Gaseous Exchange

Plants require oxygen for cellular respiration, like other organisms.
Unlike animals, plants make their own food (photosynthesis).
Efficient photosynthesis requires gas exchange.
Plants exchange oxygen and carbon dioxide through stomata, pores located on the lower epidermis of leaves.

Stomata

Stomata are pores on the lower leaf epidermis.
Each stoma has guard cells that control opening/closing by changing shape.
Guard cells have chloroplasts for photosynthesis.
Stomatal opening/closing depends on turgor pressure.
Turgor pressure is controlled by potassium ion (K+) uptake and sucrose concentration.
Potassium ion (K+) uptake changes water potential, causing water to move by osmosis between guard cells and the environment.
Sucrose concentration in guard cells affects water balance; photosynthesis increases sucrose during the day, converting it to starch overnight.

Stomatal Opening

Potassium ions (K+) move into guard cells.
Increased solute potential draws water in by osmosis.
Turgid guard cells bow outwards, opening the stoma.

Stomatal Closing

Potassium ions (K+) move out of guard cells.
Decreased solute potential causes water loss by osmosis.
Guard cells become flaccid, causing stoma to close

Water Deficiency in Plants

Adequate water supplies maintain guard cell turgor for stoma opening.
Lack of water causes guard cells to lose turgor, closing stomata to prevent water loss.
Stomata close to conserve water during periods of water deficiency.

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Description

This quiz explores the essential processes of gaseous exchange in plants, focusing on the role of stomata and guard cells. Learn how photosynthesis, potassium ion uptake, and turgor pressure contribute to the opening and closing of stomata. Test your understanding of these vital plant functions.