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17 Cards in this Set
- Front
- Back
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How does the number of stomata on the upper epidermis of a leaf compare to the number on the lower epidermis? |
The lower epidermis has many more than the upper epidermis. |
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What are stomata controlled by? |
Guard cells |
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How do guard cells open and close the stomata? |
Water enters the guard cells by osmosis, making them become turgid which opens the stomata.
Water leaves the guard cells by osmosis, causing the guard cells to become flaccid, closing the stomata. |
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What do lots of closed stomata suggest about the environmental conditions of the plant? |
It suggests the plant was in a dark place or had a lack of water. |
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How is a leaf adapted for efficient gas exchange? |
Large flat surface area to absorb as much sunlight and CO2 as possible.
Thin, meaning a shorter distance for CO2 and O2 to diffuse (Short diffusion distance).
Has stomata which control water loss to manage the temperature of the leaf and to stop photosynthesis at night. Can open to allow CO2 to diffuse in. Allows excess oxygen to diffuse out. Can close when needing to conserve water. |
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What experiment could you use to show how light intensity affects gas exchange of a leaf? |
Have four boiling tubes containing hydrogen carbonate indicator. Put the same size leaf in three of them, leaving the last as a control. Put a bung in the top of each. Wrap one tube in aluminium foil to make dark conditions. Wrap another in grease proof paper to make dim conditions and leave the last as light. |
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What is the purpose of a control test tube? |
To compare results to.
Show the change in the indicators colour.
Prove the leaf caused the change. |
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What colour does hydrogen carbonate indicator go in high CO2 concentrations? |
Yellow |
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What colour does hydrogen carbonate indicator go in air levels (0.04%) of CO2 concentration? |
Orange |
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What colour does hydrogen carbonate indicator go in low CO2 concentrations? |
Purple |
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What are the different colours hydrogen carbonate indicator goes? |
High CO2 concentration Yellow Orange Red Pink Purple Low CO2 concentration |
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What is the colour of the indicator of the leaf in the light? |
Purple as CO2 is absorbed for photosynthesis. |
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What is the colour of the indicator of the leaf in the dark? |
Yellow as CO2 is produced by respiration. |
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What is the equation for respiration? |
glucose+oxygen --> carbon dioxide + water (+energy) C6H12O6 + 6O2 --> 6CO2 + 6H2O |
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What is the equation for photosynthesis? |
Carbon dioxide + water --> glucose + oxygen
6CO2 + 6H2O --> C6H12O6 + 6CO2
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What is the compensation point? |
The light intensity at which the rate of photosynthesis is equal to the rate of respiration and there is no net gas exchange. |
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What does the compensation point mean? |
All the glucose molecules made in photosynthesis are used up in respiration and therefore there is no change in biomass (plant doesn't get bigger or smaller).
All the CO2 molecules produced in respiration are used in photosynthesis and all the O2 produced by photosynthesis is used in respiration. Therefore there is no net gas exchange with the environment. |
