Life on Earth - Photosynthesis Flashcards

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1
Q

Describe Photosynthesis

A
  • The process by which green plants and other organisms use sunlight to synthesize nutrients from carbon dioxide and water.
  • Takes place inside the chloroplasts.
  • Two stage process
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2
Q

Name and describe the 1st stage of Photosynthesis

A

1. LIGHT REACTIONS
* Light energy from the sun is trapped by the chlorophyll in chloroplasts
* Light energy is converted into chemical energy used to make ATP.
* Water splits to produce hydrogen and oxygen
* Oxygen diffuses out of cell.
* Hydrogen and ATP → passed to Carbon Fixation

(ALL IN CHRONOLOGICAL ORDER)

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3
Q

Name and describe the 2nd stage of Photosynthesis

A

2. CARBON FIXATION
* Series of enzyme-controlled reactions
* The ATP is broken down to release energy which is used to combine hydrogen (from light reactions) with carbon dioxide to produce sugar.
Hydrogen + Carbon dioxide → sugar

(ALL IN CHRONOLOGICAL ORDER)

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4
Q

Photosynthesis word equation?

A

carbon dioxide + water → sugar + oxygen

(assisted by Light energy and Chlorophyll)

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5
Q

List 4 fates (uses) of sugar

A
  1. Energy source - used in respiration
  2. Plant energy storage - can be made into glucose, then into starch
  3. Plant building material - can be made into glucose, then into cellulose
  4. Production of other types of food - sugar is a carb

Plants can combine sugar with nitrates to produce amino acids for proteins

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6
Q

Define the term ‘Limiting factor’, applying it to photosynthesis and list the 3 limiting factors of photosynthesis

A
  • Anything in short supply that prevents photosynthesis occurring at its maximum rate.
  • Light intensity, Temperature, Carbon dioxide
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7
Q

Describe the impact carbon dioxide concentration has on photosynthesis

A
  • Required to make sugar during carbon fixation.
  • No CO2? → No sugar
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8
Q

Describe the impact light intensity has on photosynthesis

A
  • Required to provide light for the light reactions.
  • No light/low light intensity? → No ATP or Hydrogen for Carbon Fixation
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9
Q

Describe the impact temperature has on photosynthesis

A
  • Affects the rate the enzymes catalysing the reactions in both stages can occur.
  • Temperature not at enzyme optimum? → Rate of photosynthesis declines.
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10
Q

How is the rate of photosynthesis and the rate of plant growth linked?

A

Provides the energy plants need to grow and develop

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