- •Autotrophic Nutrition – Nutrition in green plants.
- •1. Absorption of water and salts.
- •Mechanism of water absorption:
- •Absorption of Mineral Salts.
- •Mechanism of Salts Absorption
- •2. Selective permeability:
- •3. Active transport:
- •2. The concentration of some ions accumulated in the algal cells is higher than the concentration of other ions.
- •2. Photosynthesis in Green Plants.
- •It is clear from the table why green color dominates colors of other pigments in the plastid.
- •The structure of the leaf and it’s adaptation to Photosynthesis
- •Mechanism of Photosynthesis
- •Verifying the theory of Van neil experimentally:
- •Light reactions and dark reactions
- •2. Dark reactions of Photosynthesis:
- •Revision II
- •1. Mention the scientific term that represents each of the following:
- •I. The tissue that lies between the upper and the lower epidermis of the plant leaf. ( ------------------ )
- •2. Give reasons for each of the following:
- •I. Presence of mid-rib, veins, and venules spreading allover the leaf.
- •Heterotrophic Nutrition – Digestion in Man.
- •Enzymes.
- •Digestion in Man
- •2. Gastric Digestion (Digestion inside the stomach):
- •1. Water: 90%
- •3. Pepsin enzyme: which is secreted in an inactive form as Pepsinogen, that is activated by hCl acid into active Pepsin:
- •1. The presence of copious mucus secretion protects the inner epithelial lining of the stomach against the effect of the digestive enzymes.
- •2. Pepsinogen which is inactive will be activated only when it is mixed with the acid in the cavity of the stomach away from its wall.
- •3. Intestinal digestion (Digestion inside the small intestine):
- •Intestinal juice is secreted from certain cells in the lining of the small intestines. It contains a mixture of enzymes that completes the action of the previous enzymes:
- •Absorption of Food.
- •1. The blood route:
- •2. The lymphatic route:
- •1. Anabolism: In which the simple food substances convert into complex compounds that share in the body construction as:
- •2. Catabolism: In which the absorbed food substances are oxidized, especially sugars to produce energy which is needed by the body to carry out its vital process.
- •Revision III
- •1. Give the scientific term that represents:
- •I. The structure that joins coils and loops of the small intestines. (--------------------)
- •V. A pancreatic enzyme that catalyzes the hydrolysis of glycogen and starch into the disaccharide maltose. (---------------------)
- •I. The system that carries fats after its absorption slowly through a network of vessels. (----------------------)
- •2. Give reasons for each of the following:
- •I. Secretion of hCl acid inside the stomach is essential.
- •6. Describe the mechanism of food absorption through:
- •7. Why does the gastric juice not affect the epithelial lining of the stomach?
- •8. Describe the mechanism of defecation to get rid of the indigestible remains.
Absorption of Mineral Salts.
Essential nutrients for green plants:
Green plants need certain essential elements (other than Carbon, Hydrogen, and Oxygen). Plants absorb these elements through the root.
Deficiencies of these elements lead to:
1. Disturbances in plant growth.
2. The growth may stop completely.
3. Flowers or fruits may not produce.
These elements are divided into 2 groups:
1. Macro-nutrients:
These elements are needed by the plant in considerable quantities:
Nitrogen – Phosphorus – Sulphur - Potassium – Calcium – Magnesium – Iron.
2. Micro-nutrients:
They are also called the trace elements, because they are needed by the plant in very small quantities. (Few milligrams/liter). These elements help to activate enzymes:
Manganese – Zinc – Boron – Aluminum – Copper – Chlorine – Iodine – Molybdenum.
Mechanism of Salts Absorption
It depends on the following phenomena:
1. Diffusion:
Some salt ions move by diffusion from the soil solution where the concentration is higher and pass through the wet cellulosic walls to the less concentrated medium.
Where the salt ions behave independently of each other and of water itself as:
a. Positive ions (cations) as K+ and Ca++
b. Negative ions (anions) as Cl-, NO2-, and SO4- -.
Cation exchange may take place. A Na+ may get out of the cell and is replaced by a K+ ion.
2. Selective permeability:
When ions reach a semi permeable plasma membrane, some of them are selected to pass inwards according to the plant's requirements. Some other ions are not permitted in regardless their size, concentration, or charge.
3. Active transport:
Sometimes ions move from the salt solution where the concentration is low to the inside of the cell where the concentration is high. Energy is needed to force these ions to move against the concentration gradient.
The following graph represents the results of an experiment carried out on Nitella alga that lives in swamp water:
1. The concentration of different ions accumulated in the cell sap of the algal cells is higher than their concentration in the swamp water. This proves that the cell must use up energy to absorb these ions.
2. The concentration of some ions accumulated in the algal cells is higher than the concentration of other ions.
This proves that ions are selectively absorbed according to the requirements of the plant. Movement of any substance through the plasma membrane of the cell by the help of chemical energy is called active transport. This energy is supplied during respiration of root tissues. Since the process of aerobic respiration demands the presence of sugar and Oxygen, both of them are essential for absorption of salts by the plant.
The following graph represents the results of an experiment carried out on Barley plant to show the effect of Oxygen presence (aerobic respiration) on the absorption of sulphate ions (SO4--) ions by the plant:
The Barley plant was supplied with sulphate ions containing radioactive S35 . The quantity of absorbed salt was estimated using Geiger counter. The experiment was carried out twice:
1st: When the root is exposed to aerobic conditions.
2nd: When the root is exposed to anaerobic conditions.
The results:
1. Absorption of sulfate ions was less in the case of anaerobic conditions. So, occurenence of aerobic respiration is essential for absorption of salts to take place.
2. Salt ions accumulate in the plant cells due to energy that is released during aerobic respiration.