2101 - Photosynthesis & Respiration Flashcards

1
Q

Photosynthesis equation

A

Carbon Dioxide + Water + Light Energy = Sugar + Oxygen

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2
Q

Respiration equation

A

Sugar + Oxygen = Carbon Dioxide +. Water + Energy

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3
Q

Respiration definition

A

Respiration is the process of releasing stored energy (from Photosynthesis) within the cell for growth and cell regulation.

occurs day and night

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4
Q

Aerobic respiration

A
  • Conversion of Sugars and Oxygen into Carbon Dioxide and Water.
  • Releases of a lot of energy.
  • occurs in the mitochondria
  • requires a source of oxygen, usually atmospheric
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5
Q

Anaerobic respiration

A
  • Does not require Oxygen
  • Conversion of Sugars to Ethanol and Carbon Dioxide.
  • Release a small amount of energy.
  • Occurs in the Cytoplasm
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6
Q

Anaerobic respiration occurs when…

A

There is not enough available Oxygen.

  • Waterlogged soils
  • Seeds stored in airtight storage
  • Fruit in airtight storage

Short term ‘fix’ that enables energy production to continue in adverse conditions. Small energy release, also Ethanol build up which can cause tissue damage and lead to death.

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7
Q

Factors affecting Aerobic respiration

A

Respiration is at its highest in actively growing cells, during seed germination or cutting producing new roots.

  • Oxygen Levels, As Oxygen levels fall the rate of respiration decreases. Increase will increase in Rate of Respiration, up to a point where it will flatten.
  • Temperature, Respiration is enzyme driven, therefore rates increases with temperature. Increasing past the optimum temperature will decrease the Rate of Respiration and therefore the plant will be less productive and growth slows.
  • Respiration rate below 5c is very slow. Increases rapidly to an optimum around 25/30c, then decreases again due to enzyme de-activation and stops at 40c.
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8
Q

Respiration in Horticultural situations

A

Reducing the Rate of Respiration in stored crops, fruit, seed and bulbs. Will keep fresh for longer.
Storage facilities may reduce temperature and replace oxygen with Nitrogen to limit the rate of respiration.

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9
Q

Photosynthesis

A

Co2 + H2o + Light Energy = Sugar + o2

Occurs in the chloroplasts of plants. Typically in the leaves.
Converts co2, h2o and light into high energy sugars easily transported around the plant.

Can be efficiently converted to starch for storage (and back again when needed).

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10
Q

Factors affecting Photosynthesis

A
Light
Carbon Dioxide concentration
Temperature
Water
Availability of Chlorophyll
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11
Q

Law of limiting Factor

A

The factor is least supply will limit the rate of Photosynthesis.

This factor must be raised in order to increase rate of Photosynthesis. Irrespective of the availability of other limiting variables.

Horticulturalists try to optimise levels of the limiting factors to maximise production.

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12
Q

Sub-Optimal, Optimal, Super-Optimal levels

A

Sub-Optimal levels, will reduce the rate of growth/productivity

Optimal levels, will allow for optimal growth

Super-Optimal levels, will typically damage the plant and reduce growth/productivity

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13
Q

Factors affecting Photosynthesis - Light

A
  • Low Levels have insufficient energy to drive photosynthetic reactions.
  • Too little will cause Stomata to close reducing co2 exchange limiting photosynthesis
  • After optimum levels are reached rate of photosynthesis flattens off.
  • Too much light, can lead to bleaching/scorching and the breakdown of chlorophyll. Resulting in less growth.
    Species and situation dependant (eg desert plants or shade plants).
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14
Q

Factors affecting Photosynthesis - Quality of Light

A
  • Photosynthetically active radiation to harness light energy. Blue and Red end of the spectrum are most absorbed.

(artificial lighting systems)

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15
Q

Factors affecting Photosynthesis - co2

A
  • too little will affect rate of photosynthesis and slow growth.
  • Can increase but flattens off quickly
  • Too much results in an inability to respire, so growth is slowed but not directly because of photosynthesis
  • add gas burner to green-house, or pump in co2
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16
Q

Factors affecting Photosynthesis - Temperature

A
  • optimum 25c range, rate of photosynthesis falling rapidly below 15c and dropping when it exceeds 30c. (Species dependant).
17
Q

Factors affecting Photosynthesis - Chlorophyll

A
  • Lack of chlorophyll mean low rate of photosynthesis.
  • normally nutrient dependant. Lack of nutrients will lead to Chlorosis in the leaf and reduced photosynthetic production.
  • main nutrients needed Nitrogen, Magnesium, Iron
  • Super-Optimal nutrient availability will lead to Cell Plasmolysis. Where the water in the root will move out into the soil via osmosis.
    Potentially destroying the cell and reducing growth rate.
18
Q

Factors affecting Photosynthesis - Water

A
  • Optimal (field capacity)
  • Shortage/drought, stomata closed and prevent gaseous exchange so no co2.
  • Waterlogging, lead to aerobic respiration, leading to less energy available in the cells . And limited nutrients being absorbed by the root.