Plant Nutrition Flashcards
What are the characteristics of a greenhouse to ensure the proper growth of crops?
- Ventilation flaps : To restrict the increase in the temperature of the greenhouse.
- Shades : To restrict excessive sunlight from entering
- Paraffin heaters : To provide both CO2 and heat.
What are the four things needed for photosynthesis?
- Light : this can be from the sun or from another artificial light source.
- Chlorophyll : the pigment that gives the plants their green colour, this absorbs the energy in the sunlight and uses it to combine CO2 and water to produce glucose.
- Carbon dioxide : enters the leaf from the air around.
- Water : comes from the soil and into the leaf
Explain the amount of light as a limiting factor.
The chlorophyll uses light energy to perform photosynthesis. It can only do it as fast as the light energy is arriving. The plant actually only absorbs the red and blue ends of the visible light spectrum and reflects the green light, and so the plants appear green in colour.
Explain the amount of carbon dioxide as a limiting factor.
CO2 and water are the raw materials. Water is never really short in supply, but only 0.03% of the air around is CO2 which is pretty scarce for plants.
Explain temperature as a limiting factor.
Chlorophyll is like an enzyme and it works best when it is warm but not too hot. If the temperature is too low chlorophyll will be inactive and if the temperature is too high it gets denatured.
Explain the change in the colour of sodium hydrogen carbonate when oxygen / CO2 is produced.
When the amount of oxygen produced is more the indicator changes colour to purple (acidic). When the amount of CO2 produced is more it changes colour to yellow (basic).
Explain the function of the different types of cells in a leaf.
EPIDERMAL CELLS
- Top layer of leaf is transparent to allow the sunlight to reach the palisade cells.
- Secretes a waxy substance to prevent the excess loss of water.
PALISADE CELLS
- They are packed with chloroplasts to perform photosynthesis. Most of the photosynthesis takes place here.
- Chloroplasts are motile and move according to the direction of the sunlight.
SPONGY MESOPHYLL
- There are air spaces between them to allow the diffusion of gases and to allow CO2 to reach the palisade cells
- Contains the guard cells which contain chloroplasts and the stomata.
Explain the functions of the following adaptations of leaves:
Thin, Large surface area, Stomata, Xylem, Spongy mesophyll
- Thin : rapid diffusion of gases
- Large surface area : absorption of sunlight
- Stomata : exchange of gases
- Xylem : transport of water
- Spongy mesophyll : diffusion of gases within leaf
Explain the functions of the following adaptations of palisade cells:
Many chloroplasts, Elongated, Tightly packed, Close to upper surface, Motile chloroplasts
- Many chloroplasts : Absorption of sunlight
- Elongated : Fewer cells walls for light to pass through
- Tightly packed : Ensures no light misses cells
- Close to upper surface : To be closer to sunlight
- Motile chloroplasts : Arranges for light absorption
Explain how the stomatal pores open and close automatically.
- Stomata close automatically when supplies of water from the roots start to dry up.
- The guard cells control this. When water is scarce, they become flaccid, and they change shape, which closes the stomatal pores.
- This prevents any more water being lost, but also stops CO2 getting in, so the photosynthesis stops as well.
Explain the process of eutrophication.
- Because of the amount of fertilisers added in water bodies, the algae grow and die using up lots of oxygen and blocking sunlight.
- Aquatic plants begin to die
- Dead matter provides food for microbes
- Which increases the competition for oxygen
- Water becomes deoxygenated and fish die.
Explain the need of nitrogen for plants and what are the deficiency symptoms if it is not provided adequately.
It is needed to make amino acids (and therefore proteins and enzymes), chlorophyll and DNA.
Deficiency symptoms
- stunted growth
- upper leaves pale
- lower leaves dead
- thin stem
- roots smaller
Explain the need of magnesium for plants and what are the deficiency symptoms if it is not provided adequately.
It is needed to make chlorophyll
Deficiency symptoms
- pale or yellow leaves
What is monoculture and why is it bad?
Monoculture means growing one crop year after year.
This can be bad because:
- The plants remove the same minerals from the soil each year
- Levels of these minerals fall
- Growth is reduced
- Crop yields decrease
How can the effects of monoculture be avoided?
Farmers can:
- Apply animal manure
- Rotate crops
- Allow land to go fallow
- Use chemical fertilisers
