PHOTOSYNTHESIS

PHOTOSYNTHESIS

CO2 + H2O ——->    C6H12O6 + H2O + O2

Carbondioxide + water——-> glucose +water + oxygen

Photosynthesis is the process of converting solar energy to chemical energy.

6CO2+ 12H2O  —–>   C6H12­O6 + 6H2­O + 6O2

Importance of photosynthesis.

1. Energy
2. Oxygen production
3. Production of food
4. Balance CO­2 and O2­­in the atmosphere

Factors affecting photosynthesis (rate of)

1. Light intensity- Light intensity varies from day to day and place good quality. Light enhances the rate of photosynthesis. Very bright light damages the plant due to the strong UV rays. Plants under a shade receive poor quality of light. The best wave lengths are red and blue.

2. Carbondioxide concentration – the percentage of CO­2­in the atmosphere is 0.03% in controlled conditions example green house. An increase in CO­2 ­concentration results to an increase in the rate of photosynthesis up to a certain level.

3. Temperature- photosynthesis is controlledby enzymes.  Enzymes are affected by the changes in temperature.  High temperatures destroys enzymes and very low temperature inactive them.  A rise in temperature by 100 C results in the double rate of photosynthesis up to 400  Any further increase in temperature decreases the rate of photosynthesis.

4. Water- plants require water for various chemical reactions of the cells. It is also a raw material for photosynthesis.

5. Mineral salts- some irons such as magnesium are constituents of chlorophyll. The availability of those ions will result chlorophyll.

6. Leaf age- as the leaf ages, chlorophyll breaks down hence the rate of photosynthesis is reduced.

DEFICIENCY DISEASES FOR PROTEINS AND CARBOHYDRATES

1.Marasmus – due to lack of enough carbohydrates.

Symptoms:

Stunned growth

Tendency to eat a lot of food when available.

Child cries continually due to hunger.

Child loses weight and become thin

2.Kwashiorkor – due to lack of proteins.

Symptoms:

Hair changes

Swollen stomach

Skin becomes dry

Child becomes weak

Loss of appetite

VITAMINS

Are organic food substances needed by the body in very small quantities for normal body activities.  Vitamins can be water soluble and fat soluble.

Example of water soluble vitamins is vitamin B1, B2, B12 and Niacin.

Example of fat soluble vitamins is vitamin A, D, E and K.

Mineral elements- these are inorganic substances needed by the body in very small quantities for different body activities.

Roughage

Is a cellulose material found in food.

It adds bulk to the food, prevents constipation.

Water

Is an inorganic compound containing hydrogen and oxygen in the ratio 2:1.

Sources of water

1. Food
2. Metabolic water
3. Direct drinking

Importance of water

1. Formation of protoplasm
2. Is a medium through which materials are transported in the body
3. Medium through which chemical reactions take place
4. Maintains shape of cells and organ

Symptoms of water deficiency

1. Thirst
2. Urine decreases
3. Colour of urine changes
4. Faeces become dry

Nutrition in plants

Photosynthesis is a process of building complex organic materials from CO2 and water in presence of chlorophyll and light energy.

Mechanism of photosynthesis

CO2 +H2O    ————–>C6 H12 ­­O6 + H2­­­O +O2Equation of photosynthesis

Conditions of photosynthesis

• Light energy
• Chlorophyll
• Water
• Temperature
• CO2                                                                  

End products of photosynthesis

Primary products – glucose

By products – oxygen, water

Storage organs in plants

1. Bulbs of onions
2. Corns in yams
3. Rhizomes of ginger
4. Root tubers
5. Stem tubers

Advantages of storage organs

1. Gives rise to new plants (some)
2. Source of food (some)
3. Permit survival of plants over dry season
4. Used for commercial purposes