5.2 - Gas Exchange in Plants Flashcards Preview

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Flashcards in 5.2 - Gas Exchange in Plants Deck (21)
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Which gasses make up the air we breathe?

Oxygen, CO2, water vapour, nitrogen and other


Which gas makes up most of our air?

Nitrogen! (78%)


In what function do both plants and animals consume oxygen? What do they produce?

Both plants and animals (us!) need to perform cellular respiration. During this process we/they take in oxygen and produce carbon dioxide and water.


What process enabless plants to clean the air by taking in CO2?

Plants are capable of photosynthesis - they take in CO2 and Water to produce oxygen and glucose.


What is the formula for cellular respiration?

C6H12O6(s) + 6O2(g) ---> 6H20(l) + 6CO2(g) + ENERGY
*The reverse of the photosynthesis formula
*During cellular respiration the glucose and the oxygen are converted into ATP.


What is the formula for photosynthesis?

6CO2(g) + 6H2O(l) + LIGHT ENERGY ---> C6H12O6(s) + 6O2(g)
*During photosynthesis: plants consume greater CO2 than they release during cellular respiration (hence the "cleaning the air")


What is the most important gas-exchange organ in the plant?

The leaf is considered the plants most important gas exchange organ (yes, it is an organ, b/c its made up of tissues)


Explain the process of CO2 entering the leaf and what happens.

Carbon dioxide enters the leaf through the stomata. They then diffuse through the cell membrane of the spongy tissue cells and once dissolved, are used by photosynthesis.


At what point does oxygen leave the cells? How does it leave?

After photosynthesis, oxygen diffuses out of the cells and exits the leaf through the stomata.


How does water move into and out of the cell?

Water is pulled up from the roots by the xylem and exits as water vapour through the stomata.


What perforations allow gas exchange in woody plants?

Lenticels - lens-shaped openings perforating the bark. They allow gas exchange between the bark (outer bark is dead old cells and the inner bark is living) and the living cells


What causes water loss in a plant?

Air diffusion out of the stomata causes water loss.


What is transpiration

THe evaporation of water from leaves


What prevents plant cells from drying out?

Guard cells are able to change their shape to cause the stomata to open and close. When the stomata are closed, gas exchange and water exchange are reduced.


Why are high rates of photosynthesis possible when stomata are open?

When the stomata are open CO2 can enter the leaf and oxygen and water vapour exit. Plants require CO2 and water for photosynthesis which results in oxygen and glucose.


How many litres of water can a tree lose?



How do plants regulate water loss? Describe how this action occurs.

By closing the guard cells. Guard cells have thinner exterior walls than interior - cell fills with water (due to an increase of K+ inside the cell), the thinner outside wall pushes out, causing the stomata to open.


In the guard cells what is the pressure called which causes the cells to remain rigid.

Water s moving into guard cells by osmosis. The pressure inside the cell increases and causes swelling of the cell. High pressure = turgor pressure.


What happens to cells as transpiration occurs?

Water exits the cells and cells deflate


In most plants what is the stomata open/closed schedule?

Open during the day and closed at night


What are the factors that affect the rate of transpiration?

- Light: More sun = stomata open = water exits = more photosynthesis necessary
- Humidity: Greater relative humidity (the amt of water in the air (in %) compared to the theoretical max amt (saturation pt in %)) = less transpiration b/c it is easier for water to evaporate into dry air than saturated air
- Temp: Higher temp = higher rate of evaporation