PHOTOSYNTHESIS (SL) Flashcards

1
Q

Why does photosynthesis do photolysis

A

To break down the water to get the electrons from the hydrogen molecules
- why they have oxygen as their “waste”/byproduct

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2
Q

Who were the first organisms to perform photosynthesis?

A

Prokaryotes
- the great oxygenation event

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3
Q

Define photon

A

unit/particle of light

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4
Q

What are the wavelengths that green plants use? (active spectrum)

A
  • red and blue
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5
Q

Relationship of photons and pigment molecules

A
  • Photons absorbed by pigment molecules
  • by a specific amount of energy, excitation (electron of pigment to higher energy level)
  • for only specific wavelengths of light
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6
Q

Why is green light reflected in green plants?

A

Because chlorophyll isn’t excited by photon
- therefore, green light is reflected

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7
Q

Define absorption spectrum

A

which wavelengths of light are absorbed by the material and which ones pass through.

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8
Q

Differentiate action spectrum vs absorption spectrum

A
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9
Q

Why is carbon dioxide a means for predicting future rates of photosynthesis and plant growth?

A
  • because carbon dioxide concentration is directly proportional with the rate of photosynthesis
  • as a reactant
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10
Q

Light Spectrum

A

The electromagnetic spectrum comprises the full range of all types of radiation energy (travels through space in particles or waves)

  • The sun emits its peak power in the visible region of this spectrum (white light = 400nm – 700nm)
  • Colours represent different wavelengths of visible light and range from red (longest) to violet (shortest)
  • sThe colours of the visible spectrum (from longest to shortest) are red, orange, yellow, green, blue, indigo, violet
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11
Q

Pigment Molecules

A
  • Each contains electrons at discrete and specific energy levels (according to the pigment’s atomic configuration)
  • Absorb light at specific frequencies (or wavelengths) and become energised and delocalised (ionised)

The energy from these excited electrons can be harnessed by the cell to make chemical energy (ATP – via photophosphorylation)

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12
Q

Action spectrum

A

overall rate of photosynthesis at each wavelength of light

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13
Q

Enclosed Greenhouse Experiments

A

Carbon dioxide levels can be artificially increased in indoor greenhouses by adding CO2 from compressed gas tanks or by adding fermentation buckets that continuously produce CO2

  • Enclosed greenhouses act as a closed system, which allow for the control of a range of extraneous variables (such as temperature and light)

-** However the conditions do not reflect those that occur in the natural environment** and only plants that grow in small spaces can be measured

Basically controlled experiment not reflect irl

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14
Q

Free Air CO2 Enrichment (FACE)

A

Free air carbon dioxide enrichment experiments involve the placement of pipes which emit CO2 around an experimental area

  • The concentration of carbon dioxide is monitored by sensors which then adjust the flow of CO2 from the pipes
  • FACE experiments represent** open systems which incorporate natural conditions** like rainfall and temperature fluctuations
  • FACE experiments can also measure the effects of CO2 enrichment on larger trees and consider the impact of competition between plant species
  • The disadvantage of experimenting on open systems** is that certain conditions (such as sunlight) cannot be controlled**
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15
Q

Light Dependent Rxns

A
  • occurs in thylakoids, membrous discs in the chloroplast
  • ** resulting in the production of ATP** (chemical energy)
  • photolysis, the light absorbed the water and splits it to produce oxygen and hydrogen
  • photolysis is used** to produce oxygen (byproduct) and hydrogen** (carried by the NADPH for the calvin cycle)
  • The hydrogen and ATP are used in the light independent reactions, the oxygen is released from stomata as a waste product
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16
Q

Light Independent Reactions

A
  • in stroma
  • ATP and hydrogen (carried by NADPH) are transferred to the site of the light independent reactions
  • The hydrogen is combined with carbon dioxide to form complex organic compounds (e.g. carbohydrates, amino acids, etc.)
  • The carbon is fixed by the enzyme Rubisco, with ATP providing the chemical energy required to join the molecules together
  • This process is also commonly known as the Calvin cycle
17
Q

Enzyme as a factor in the rate of photosynthesis

A
  • Temperature affects the rate of photosynthesis by** impacting the frequency of successful enzyme-substrate collisions**
  • pH affects rate of photosynthesis by changing the charge and solubility of the enzymes involved
18
Q

Photosynthetic Inputs (effect of Co2)

A
  • Carbon dioxide is the main source of carbon used to synthesise organic compounds in the light independent reactions
  • Increasing concentrations of carbon dioxide will result in higher rates of photosynthesis until all enzymes (e.g. Rubisco) are saturated (resulting in a plateau)
  • The concentration of carbon dioxide can be experimentally regulated by using tablets of sodium bicarbonate (baking soda)
  • Sodium bicarbonate dissolves in water to form carbonic acid – which readily dissociates to form carbon dioxide
19
Q

How to measure photosynthesis?

A

1.) CO2 Uptake
- measured by placing lead tissue in an enclosed space with water
- co2 implemented -> bicarbonate hydrogen ions -> ^ acidity
- lower the concenration in solution by intake
- datalog
2.) O2 production
- submerging of plant in water-filled space
- bubbles
- or submerged leaf discs to surface
3.) Biomass
- indirectly measured by a change in the plant’s biomass (weight)

20
Q

Chromatography formula

A

Rf value = distance component travels ÷ distance solvent travels

21
Q

Define FACE

A

Free air carbond dioxide enrichment experiments

22
Q

What are the questions asked in FACE?

A
23
Q

What is the IV in FACE experiments?

A

CO2

24
Q

What are the DV in FACE experiment?

A
  • plant growth
  • rates of photosynthesis
25
Q
A