Plant Transport and Plant Disease

  • Created by: jB1rd_
  • Created on: 09-04-19 10:00

Photosynthesis

Plants photosynthesize to create glucose which is used to respire, build cell walls, grow, store as starch, etc.

Formula : 6CO2 + 6H2O —> C6H12O6 + 6O2

Limiting Factors: Light Colour, Light Intensity, Temperature, pH, Volume of Water, CO2 Concentration, Humidity(higher = lower conc gradient), Wind Speed(more H20).

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Plant Adaptations

-Thick Waxy Cuticle: minimise water loss

- Small surface area: "

- Poisons: for defence

- Large Stem: Increased water storage

- Bright Colours

- Spikes

- Curled leaves

- Long roots

- Trapped moist air

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Xylem and Phloem

Xylem vessels transport water and minerals from the root to the leaf and stem to replace water lost through transpiration.

Phloem cells transport nutrients such as dissolved sugars from the leaves to the rest of the plant.

Xylem: Dead Cells, Thick Cell Wall of Lignin(rigid), Impermeable, No Cytoplasm, Transport water and minerals, carried to leaves, flows upwards, tissue also has fibre

Phloem: Living cells, thin cell wall made of cellulose, permeable, has cytoplasm lining, transports food, carried to growing parts and storage organs, flows up and down, tissue also has companion cells

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Transpiration

The movement of water from the roots out through the leaves. Water is lost through the stomata in the leaves by evaporation. More water is lost on dry hot and windy days. 

Transpiration stream is the term used to refer to the movement of water through the plant from entering through the roots leaving via the leaf

1. Water evaporates through the stomata

2. Water moves into the leaf through the Xylem vessels by osmosis

3. Water is pulled upwards through the xylem tissue

4. This is replaced by water from the roots

5. Water enters the root hair cells by osmosis to replace the water lost through transpiration

Potometer used to measure transpiration.

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Plant Disease

Plants can be affected by a range of fungal, bacterial and viral infections.

You can tell a plant has a disease if it has:

  • Stunted Growth 
  • Spots on leaves
  • Areas of decay
  • Growths
  • Malformed stem or leaves
  • Discolouration
  • The presence of pests
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Tobacco Mosaic Virus and Rose Black Spot

TMV

TMV  is a widespread plant pathogen which affects many species of plant including tomatoes.

TMV gives a distinct 'mosaic' pattern of discolouration on the leaves which affect the growth of the plant due to lack of photosynthesis.

Rose Black Spot

RBS is a fungal disease where purple or black spots develop on leaves which often turn yellow and drop early.

RBS affects the growth of the plant as photosynthesis is reduced.

RBS is spread in the environment by water or wind

RBS can be treated by using fungicides and or removing and destroying the affected tissues

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Deficiencies

Nitrates

  • Needed to make proteins.
  • Proteins are essential for growth. 
  • Deficiency results in stunted growth

Magnesium

  • Produces green pigment chlorophyll needed for photosynthesis
  • A deficiency results in yellow leaves and stunted growth

Potassium

  • Enzymes need potassium if they are to work properly
  • Deficiency results in necrosis

Phosphates

  • Needed to make DNA and helps form all new membranes
  • Deficiency leads to purple colour then necrosis
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Plant Meristems

Plant cells are different from animal cells. Unspecialised stem cells in plants are grouped in structures called meristems. Cells produced by meristems give rise to various organs of a plant and are responsible for growth.

Plant meristems divide to produce cells that increase the height of the plant, length of roots and girth of the stem. They also produce cells that develop into leaves and flowers.

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