Plant nutrition

• What happens at low temp

  The chemical reactions of photosynthesis can only take place very slowly at low temperature so a plant can photosynthesize faster on a warm day than on a cold one
• What happens as the more co2 a plant is given ?

  The faster it can photosynthesize up to a point but then a maximum is reach
• Is co2 a key limiting factor in photosynthesis?

  Yes the usual atmospheric level of carbon dioxide is 0.03% in perfect conditions of water availability light and temperature this low carbon dioxide level hold back the photosynthetic potential
• What happens when the rate becomes constant ?

  Light is not a limiting factor

  Even if more light is shone into the plant it still cannot photosynthesize any faster
• What happens if the first part of the curve ?

  Light is a limiting factor

  The plant is limited in how fast it can photosynthesize beacause it does not have enough light
• What happens as the light intesnsity increases ?

  The rate of photosynthesis will increase until the plant is photosynthesizing as fast as it can . At this point even if the light becomes brighter the plant cannot photosynthesizing any faster
• Is light intensity vital to the rate of photosynthesis?

  Yes , it is severely limiting at times of partial light conditions
• What happens if a component is in low supply ?


  Then productivity is prevented from reaching maximum
• What three factors can limit the speed of photosynthesis?

  Light intensity, carbon dioxide, concentration, and temperature
• limiting factor


  Is something presents, in the environment in such short supply, that it restricts life processes
• Why does the rate fall gradually ?

  At a certain Co2 concentration it stays constant

  here, a rise in carbon dioxide levels has no effect as the other factors, such as light intensity become limiting
• How does the rate of photosynthesis increase ?

  The rate increases linearly with increasing co2 concentration
• What does increasing the concentration of co2 do ?

  It increase the rate of photosynthesis
• What happens when the CO2 is low and why ?

  The rate of photosynthesis is also low . This is because co2 is the substrate of the reaction .
• What happens above 40 degrees and why ?

  At temperatures above 40 degrees the rate of slows down

  This is because the enzymes involved in the chemical reactions of photosynthesis are temperature sensitive and destroyed at higher temps
• What happens at optimum temperature?

  At the optimum temperature , the enzyme is most efficient and rate is maximum
• What happens when the temp rises for the enzymes

  When the temperature rises the particles in the reaction move quicker and collide more so the rate of photosynthesis also rises
• What happens to the enzymes at low temp?

  Add low temperature enzymes do not have enough energy to collide with many substrate molecules so the reaction is slowed
• What happens beyond optimum temp

  The reaction quickly comes to a halt
• What is an optimum temperature?


  There is an optimum temp at which the rate of photosynthesis is maximum
• What happens when the temperature rises ?

  The rate of photosynthesis also rises
• What is light intensity directly proportional to ?

  Light intensity is directly proportional to the rate of photosynthesis up to a certain point
• What could be the reason for the rate b coming constant at high light intensities?

  There might not be enough chlorophyll pigment to absorb such high light but intensities
• What other damage can be caused by High light intensities?

  Moreover, the chlorophyll system can be damaged by very intense light levels
• Why does this happen ?

  The plant is unable to harvest the light at these high intensities because other factors are limiting the rate
• What happens at high light intensities ?

  The rate becomes constant

  Even with further increases in light intensity, there is no increase in the rate
• Will the rate continue to increase

  ?

  However the rate will not increase beyond a certain level of light intensity
• What happens are the light intensity increases ?

  The rate of photosynthesis increases
• What happens at very low light intentsities ?

  The plant will be respiring only not photosynthesizing
• What is light energy absorbed by ?

  chlorophyll
• What does too much fertilizer do?

  Application of too much nitrogen fertilizer causes water to be drawn out of plant roots (osmosis). As a result, the plant will wilt/die
• Eutrophication


  Nitrates can be leached out of the soil and enter nearby body of water. The additional nitrogen leads to the formation of algal blooms (A layer-of green algae on the surface )causing lack of light thus preventing the aqua plants photosynthesizing. When the algae die they are decamped by decomposers (bacteria )which respire using O2 and create anoxic conditions this results in the death of aquatic animals from lack of O2
• Nitrates can be replaced in 3 ways :

  applying animal manure

  Crop rotation —>growing Leguminous plants such as peas beans and clover every two or three years these plans develop root nodules containing nitrogen-fixing bacteria and the roads are ploughed into the soil ,boosting nitrate levels

  Adding artificial fertilizers such as ammonium nitrate
• What does intensive farming cause ?

  Removes nitrates from the soil. These need to be replaced to prevent a drop in yield
• Nitrogen fertilizers


  Fertilizers are chemical compounds rich in the mineral ions needed by the plants. They helps the plants grow faster, increase in size and become greener, they simply make them healthier and increase the crop yield.
• What does deficiency of magnesium cause

  Deficiency makes leaves turn yellow from the bottom of the stem upwards (a process called chlorosis) and eventually stops photosynthesis
• What are magnesium ions used for ?


  Used for the manufacture of chlorophyll
• How do plants absorb magnesium ?

  Plants absorb magnesium ions from the soil solution
• What does deficiency of nitrate ions cause ?

  Deficiency causes poor/stunted growth,especially of leaves . The stem becomes weak , lower leaves become yellow and die , while upper leaves turn pale green.
• How are amino acids synthesized

  Nitrate ions combine with glucose