B8 - Photosynthesis Flashcards

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1
Q

What is photosynthesis

A

An endothermic chemical reaction that takes in light energy due to the chlorophyll in the chloroplasts

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2
Q

Equations for photosynthesis

A

carbon dioxide + water —> glucose + oxygen
6CO₂ + 6H₂O —> C6H12O6 + 6O₂

Light also goes above arrow and chlorophyll goes below

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3
Q

Factors that affect the rate of photosynthesis

A
  • Conc. of CO2
  • Light intensity
  • Amount of chlorophyll
  • Temperature
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4
Q

Describe the relationship between light intensity and photosynthesis rate

A
  • As light intensity increases, so does the rate of photosynthesis if it was a limiting factor
  • This is due to there being more light energy
  • However, this levels off and stays constant indicating that it is no longer a limiting factor
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5
Q

Describe the relationship between CO2 conc. and photosynthesis rate

A
  • As CO2 conc. increases, so does the rate of photosynthesis if it was a limiting factor
  • However, this levels off and stays constant indicating that it is no longer a limiting factor
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6
Q

Describe the relationship between temperature and photosynthesis rate

A
  • As temp. increases, so does the rate of photosynthesis if it was a limiting factor
  • This is due to there being more collisions with enzymes
  • However, if the temperature increases too much, the enzymes will denature and photosynthesis rate decreases
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7
Q

Describe the relationship between the amount of chlorophyll and photosynthesis rate

A
  • As the amount of chlrophyll increases, the rate of photosynthesis also increases
  • This is due to more light energy being absorbed
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8
Q

Leaf adaptations for light absorbtion for photosynthesis

A
  • Large SA to absorb more light
  • Palisade mesophyll cells have lots of chlorophyll in chloroplasts
  • Upper epidermis is transparent to allow light through
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9
Q

Uses of glucose produced in photsynthesis

A
  • Respiration to release energy
  • Starch - energy store
  • Lipids - energy store
  • Cellulose - structure
  • Amino acids - synthesise proteins for growth + repair
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10
Q

What is needed for plants to make proteins

A
  • Glucose to make amino acids
  • Nitrate ions absorbed from soil or from insects (carnivorous plants)
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11
Q

What ion is needed to make chlorophyll

A

Magneisum ions

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12
Q

How to test if a leaf has photosynthesised

A
  • Boil the leaf to kill it
  • Place in boiling alcohol to remove chlorophyll making it white
  • Place the leaf in hot water to soften it
  • Add drops of iodine

If starch is present, iodine will go blue/black and it means photosynthesis has occured

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13
Q

Relationship between light intenisty and distance from light source

Inverse square law

A
  • As distance increases, light intensity decreases
  • Light intensity is proportional to the inverse of the distance from the light squared
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14
Q

Method for photosynthesis practical

A
  • Place LED 10cm away from boiling tube
  • Fill boiling tube with water and sodium hydrogen carbonate (release carbon dioxide)
  • Add pondweed with cut end at the top and leave to acclimatise
  • After 5 mins, start a stopwatch and count the number of bubbles produced in one minute
  • Repeat to find a mean
  • Repeat at different distances e.g. 20cm, 30cm
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15
Q

Control variables for photsynthesis practical

A
  • Temperature
  • Type of light source
  • Concentration of bicarbonate
  • Piece of pondweed
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16
Q

Leaf adaptations for carbon dioxide intake

A
  • Guard cells open and close stomata
  • Air spaces to allow diffusion inot leaf cells
  • Leaves are thin for short diffusion distances
17
Q

Root hair cell adaptations for water intake

A
  • Large SA for increased absorbtion
  • Lots of mitochondria to provide energy for active transport
18
Q

Why can glucose not be stored as itself in the plant

A
  • Glucose is soluble and would affect movement of water in snd out of plant by osmosis