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28 Cards in this Set
- Front
- Back
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Write the word equation and the chemical symbol equation for photosynthesis.
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Water + Carbon Dioxide -(light and chlorophyll)-> Oxygen + Glucose
6H2O + 6CO2 -(light and chlorophyll)-> C6H12O6 +6O2 |
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What are the three limiting factors of photosynthesis?
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Carbon dioxide concentration, light intensity and temperature. Only the factor in shortest supply will limit the rate of photosynthesis.
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What happens to the rate of photosynthesis when the light intensity gets brighter?
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Photosynthesis increases as light gets brighter, until it no longer becomes the limiting factor. Plants spread their leaves to catch as much light as they can.
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What happens to the rate of photosynthesis when the temperature increases?
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An increase in temperature increases the rate of photosynthesis until around 40°C, at which point the enzymes in photosynthesis get denatured.
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What happens to the rate of photosynthesis when there is an increase in carbon dioxide levels?
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An increase in carbon dioxide increases the rate of photosynthesis, but can not normally be changed with outdoor plants.
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How are the upper and lower epidermis adapted for photosynthesis?
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Upper and Lower epidermis are thin and transparent to allow more light to reach the palisade cells.
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How is the wax cuticle adapted for photosynthesis?
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Is thin to protect and waterproof the leaf without blocking light.
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How are the palisade cells adapted for photosynthesis?
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The palisade cell layer is at the top of the leaf in order to absorb more sunlight. They also contain more chloroplasts in order to absorb all available light.
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How are the spongy cells adapted for photosynthesis?
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The cells are rounded and loosely packed to create air spaces which allow CO2 to diffuse through; increases surface area.
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How are the stomata adapted for photosynthesis?
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The stomata are pores that are opened and closed by guard cells in the lower epidermis. They allow carbon dioxide to diffuse into the leaf. They also allow oxygen and water vapour to diffuse out.
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What are the functions of guard cells?
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They open and close the stomata because of osmosis. Water passes into the cells by osmosis, making them bend outwards and opening the stoma. However, at night, water passes out of the guard cells by osmosis, closing the stoma.
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What are the functions of the xylem?
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Water and mineral ions are supplied to the leaf through these vessels.
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What are the functions of the phloem?
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The products of photosynthesis (sugars) are carried away from the mesophyll cells by the phloem. It supplies all other parts of the plant that can't make their own food.
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What is the mesophyll?
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This is the middle of the leaf that contains the spongy layer and the palisade layer.
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How are carbon dioxide and oxygen exchanged in bright daylight?
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A lot of carbon dioxide is taken in for photosynthesis, which then gives out a lot of oxygen. Very little oxygen is taken in for respiration, so very little carbon dioxide is given out.
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How are carbon dioxide and oxygen exchanged in dim daylight?
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Some carbon dioxide is taken in for photosynthesis, which then gives out some oxygen. Very little oxygen is taken in for respiration, so very little carbon dioxide is given out.
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How are carbon dioxide and oxygen exchanged in the dark?
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No carbon dioxide is taken in for photosynthesis, so no oxygen is given out. Very little oxygen is taken in for respiration, so very little carbon dioxide is given out.
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Describe the position of the stomata at different times during the day.
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Stomata usually open during the day to allow carbon dioxide to diffuse into the leaf, while also allowing oxygen and water vapour to diffuse out. Stomata are closed at night as there is no need for carbon dioxide without photosynthesis.
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Why do plants require mineral ions?
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Plants need mineral salts/nutrients, which are usually found in soil for growth. They are taken up in small amounts by the roots.
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Why do plants require magnesium ions?
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Magnesium is used to make chlorophyll. Yellow leaves tend to lack magnesium.
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Why do plants require nitrate ions?
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Plants need nitrates to make proteins with nitrogen.
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Describe an experiment showing the production of oxygen as a result of photosynthesis.
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1) Set up apparatus to collect bubbles of gas given off by a pondweed
2) Dissolve sodium hydrogencarbonate to the water (Adds CO2) 3) Place apparatus in light 4) Test gas for oxygen with a glowing splint. |
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Describe an experiment showing the production of starch in photosynthesis.
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1) Dip a leaf in boiling water to soften it
2) Put the leaf in a test tube of ethanol and stand it in a beaker of hot water to remove the colour from the leaf 3) Wash the leaf in cold water 4) Spread the leaf out flat and cover it with iodine 5) If the leaf goes blue black, starch is present. |
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Describe an experiment showing the requirement of light in photosynthesis.
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1) Take a destarched plant
2) Cover a part of a leaf with tin foil to reflect light 3) Leave the plant in sunlight for a few hours 4) Test the leaf for starch, foil wrapped part should not have starch present |
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Describe an experiment showing the requirement of carbon dioxide in photosynthesis.
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1) Take a destarched plant
2) Enclose it in a plastic bag with soda lime (Calcium Hydroxide), absorbing CO2 3) Leave the plant in sunlight for a few hours 4) Test for starch against a control plant. |
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Describe an experiment showing the requirement of chlorophyll in photosynthesis.
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1) Take a plant with variegated leaves (green parts and non-green parts on leaf).
2) Leave in sunlight for a few hours. 3) Test for starch. (Green parts should be positive, non-green parts should be negative) |
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Why does the net exchange of gas depend on the intensity of light?
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The net exchange is dependent on the gas exchanged during photosynthesis, and as a result is dependent on light. In the daytime, more oxygen is produced that what is used up in photosynthesis. In the night, only carbon dioxide is produced.
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How can hydrogen-carbonate indicator be used to investigate the effect of light on net gas exchange?
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Set up 3 boiling tubes with 5ml of hydrogencarbonate indicator in each tubea
Put a leaf in tube 1 and 2. The underside of the leaf should face inwards. Put tube 1 in darkness by covering the tube in tin foil. Leave all tubes near a light for 3 hours If CO2 is added to the air, the indicator will turn yellow. If CO2 is used up in the air, the indicator will turn purple. |
