Photosynthesis

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What is the source of energy for photosynthesis?
Sunlight
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Is photosythesis endothermic or exothermic?
It is endothermic, meaning energy needs to go in
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What are each of the following parts of a leaf: a) stomata b) palisade layer c) guard cell d) spongy mesophyll e) waxy cuticle?
a) holes in the underside of a leaf b) layer where photosynthesis happens c) cell that controls the size of the stomata d) layer containing air pockets e) waterproof layer on top of leaf
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Where does photosynthesis take place?
In the chloroplasts. The chlorophyll in the chloroplasts absorbs light energy and produces glucose and starch
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What things are needed for photosynthesis?
1. Sunlight 2. Water 3. Carbon dioxide 4. Chlorophyll
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What is the word equation for photosynthesis?
Carbon dioxide+water -[with sunlight and chlorophyll]-> glucose+oxygen
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What is the chemical equation for photosynthesis?
6CO2+6H2O-[with sunlight and chlorophyll]-> C6H12O6+6O2
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What is the glucose produced by photosynthesis used for and stored as?
It is used for energy through respiration and is stored as starch. It can also be converted to cellulose for cell walls and some is converted to amino acids for protein for growth
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Even though oxygen is the waste product, what can it be used for?
It can be used by the plant in respiration or it can diffuse out of the leaf and we can use it for respiration
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What can the rate of photosynthesis be limited by?
1. Light intensity 2. Carbon dioxide 3. Temperature
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What is the experiment for the effect of CO2 on photosynthesis?
-Destarch the leaf by leaving it in the dark for 48 hours so that all starch present was made during the experiment. -Use 2 leaves from the same plant, leaf 1 will have been deprived of CO2 and leaf 2 will have had a good supply
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What is the experiment for the effect of CO2 on photosynthesis? (Cont.)
-Put iodine on each leaf. -Leaf 1 will stay yellow-brown as no CO2 means no p'syn, so no starch stored -Leaf 2 will be blue-black as there has been p'syn
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How do you test a leaf for starch?
-Boil the leaf in water to stop further reactions -Turn off bunsen burner -Put leaf in test tube of ethanol to remove chlorophyll -Rinse the leaf to remove the ethanol and soften leaf -Place on tile and add iodine -Check what colour it turns
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How do you measure the rate of photosynthesis?
-Place a lamp a set distance away from the glass tank containing pondweed -Measure the volume/number of bubbles produced in a set period of time -Repeat with the light further away (wait 5 mins before measuring so plant adjusts)
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What equation do you use to find the rate of photosynthesis?
Volume of oxygen produced/time
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Why is counting the bubbles inaccurate and what can you do instead?
The bubbles may vary in size and so would hae different amounts of oxygen. Therefore it is better to measure the volume of oxygen
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Why are greenhouses well adapted to speed up photosynthesis and make more food?
-They allow plenty of light in. -The glass allows more heat in than out, increasing temperature. -CO2 cylinders raise the level of CO2 slightly. -They use water systems with plenty of mineral fertiliser.
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What is a limiting factor?
A factor which prevents a reaction from taking place at its maximum rate. eg. light, CO2 and temperature are the limiting factors of p'syn
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What are the colours hydrogencarbonate indicator will turn and what do they mean?
1. RED means there is normal CO2 -The rate of resp=rate of p'syn -the CO2 produced in resp is used in p'syn -No net gas exchange -dim light eg. dawn or dusk
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What are the colours hydrogencarbonate indicator will turn and what do they mean? (Cont.)
2. PURPLE means there is low CO2 -the rate of p'syn > rate of resp - more CO2 being used in p'syn than made in resp. -Bright light
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What are the colours hydrogencarbonate indicator will turn and what do they mean? (Cont..)
3. YELLOW means there is high CO2 -the rate of resp > rate of p'syn [OR in darkness] -NO p'syn, only respiration
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How is light absorption maximised in a leaf?
-Large surface area -Thin and transparent cuticle and epidermis so light gets to palisade layer -Presence of chloroplasts -Regular arrangement of palisade cells
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How is gas exchange maximised in a leaf?
- Stomata allow gas exchange - Intercellular air spaces in the spongy mesophyll allow diffusing of gases
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Other cards in this set

Card 2

Front

Is photosythesis endothermic or exothermic?

Back

It is endothermic, meaning energy needs to go in

Card 3

Front

What are each of the following parts of a leaf: a) stomata b) palisade layer c) guard cell d) spongy mesophyll e) waxy cuticle?

Back

Preview of the front of card 3

Card 4

Front

Where does photosynthesis take place?

Back

Preview of the front of card 4

Card 5

Front

What things are needed for photosynthesis?

Back

Preview of the front of card 5
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