- •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.
It is clear from the table why green color dominates colors of other pigments in the plastid.
The role of chlorophyll: Is to absorb light energy required for plants to carry out photosynthesis.
The structure of chlorophyll molecule:
The structure of the chlorophyll molecule is complex, it has the molecular formula: C55H72O5N4Mg. The Magnesium atom occupies the centre of the molecule; there is a relationship between the presence of Mg in the chlorophyll and the ability of chlorophyll to absorb light.
N.B: Starch grains are produced inside the chloroplast. They are minute in its size, and are the temporary product of photosynthesis. They will soon change back to soluble sugar in order to be translocated to other organs of the plant.
The structure of the leaf and it’s adaptation to Photosynthesis
1. Leaves are arranged on the stem and branches of the plant in a certain manner that facilitates their exposure to the largest amount of sunlight.
2. The leaf blade is thin and flattened to receive as much light as possible.
3. The leaf blade is supported by the midrib which branched into lateral veins and venules forming a network that spreads all over the leaf.
4. The network of veins, and venules supply the leaf with water and absorbed salts from the root. It also helps to translocate manufactured high-energy food from the leaf to other parts of the plant.
5. Both the upper and the lower surfaces of the leaf are covered with a layer of cutin to reduce water loss except for stomata, which are the main sites for gaseous exchange between the atmosphere and the interior of the leaf. Stomata often open in the light and close in the dark. Opening of stomata is affected also by the degree of humidity in air, so the plant leaves control the rate of water evaporation from the plant.
The structure of the plant leaf:
The leaf is composed of three main tissues:
1. The upper and the lower epidermis:
Each is composed of one row of adjacent, barrel-shaped parenchyma cells with no chlorophyll. Stomata spread between them, and the outer walls of these cells are covered with cutin.
2. The mesophyll tissue:
Lie between the upper and the lower epidermis and it is transversed by veins. It consists of two main layers:
a. The Palisade layer:
It lies below the upper epidermis. It consists of one row of elongated cylindrical parenchyma cells that are arranged in a columnar form perpendicular to the leaf surface. Palisade cells possess many chloroplasts that are arranged at the upper parts of these cells to receive as much sunrays as possible.
b. The spongy layer:
It lies below the palisade layer. It consists of irregularly shaped and loosely arranged parenchyma cells with large intercellular spaces between them. Spongy cells contain less chloroplasts than the palisade cells.
3. The vascular tissue:
The midrib contains the main vascular bundle, while veins and venules contain many smaller secondary vascular bundles. Inside the vascular bundle there are xylem vessels that are arranged in vertical rows between which xylem parenchyma cells exist. Next to xylem towards the lower surface of the leaf, phloem exists. Phloem translocates the soluble organic foodstuffs that are formed in the mesophyll to all the plant parts.