production of food as carbohydrates, proteins, fats and vitamins -

It is the source of industrial row materials as wood, fibers ,fats. etc -

It is the source of fuels such as coal, petroleum and natural gas -

It is the source of oxygen required for respiration process -


Raw materials required for photosynthesis *

Water : is the source of hydrogen needed to reduce CO2 -

CO2 is the source of carbon which reduced to form carbohydrate -

Phosphorus: is required in producing energy compounds ATP -

Magnesium: is required in the formation of chlorophyll molecules -

Iron: is important for building up of some photosynthesis enzymes -

Mineral salts: as nitrates, phosphates & sulphates to convert carbohydrates into proteins -

Products of photosynthesis

Monosaccharides are the main products of photosynthesis

Oxygen the second product of photosynthesis

The structure of the chlorophyll molecule, is C55 H72 O5 N4Mg -
The Mg atom at centre -

The rate of photosynthesis can be determined by

Estimating the amount of carbohydrates. 1 gm/hour /m2 -

counting the number of O2 bubbles which evolve in a unit time -

the structure of the chloroplast

( Double thin membrane + Stroma + Grana )

The pigments of the chloroplast are

The adaptation of the leaf to carry out photosynthesis *

The leaves arrangement to exposed to the maximum amount of sun light -

The leaf blade is thin & flattened to absorb much light -

The blade has midrib to keep it open & to carry water, salts & food -

The stomata at the lower surface to exchange gases & to decrease water loss -

The two surfaces of the leaf are covered with cutin to decrease water loss -





The adaptations of the leaf epidermal cells





The cells are barrel shaped to converge the light into the inner tissue -

The cells are transparent to allow the passage of the sun rays -

It is covered with cutin to protect the leaf against pests &decrease water toss -

The cells are adjacent and compact to protect the inner tissues -

The mesophyll lies between the upper & the lower epidermal layers

Spongy tissue *

It is irregular parenchyma cells -
It has wide intercellular spaces -
It has a few No. of chloroplasts -
Its functions are store food, gas exchange and photosynthesis -

palisade tissue

cylindrical, parenchyma cells -
has narrow intercellular spaces -
has many chloroplasts -
its function is the photosynthesis -

The vascular tissue is formed of many vascular bundles distributed in the veins & venules *

The vascular system in the leaf **

They are arranged inside the bundle towards to the upper epidermis, The protoxylem are -
directed upwards

Xylem vessels and separated by xylem parenchyma -

The function of the xylem: support & supply the leaf with water&salts -
Phloem lies toward to the lower epidermis, It consists of sieve tubes, companion cells and phloem parenchyma

The function of the phloem it transport the soluble organic food from the mesophyll to the other plant parts -

The Mechanism Of Photosynthesise

The source of the released O2

Van Neil studied green purple bacteria which contain simple chlorophyll -

Green purple bacteria use H2S as a source of Hydrogen instead of H2O

An experiment to prove that H2O is the source of O2 in photosynthesis

The Chlorella algae was divided into two groups, each group was left to carry out photosynthesis as following

A) The first group of the algae was left to absorb H2O formed of radioactive Oxygen O18 while the CO2 was formed of non-radioactive Oxygen O16 the results was as the following

The experiment was repeated after reversing the consitions H2O formed of normal O16 while CO2 has O "18" the results was as following

light and dark reactions

Blackman concluded that photosynthesis takes place in two main steps, light & dark reactions -

The light reactions

(the light is the limited factor )

When the chloroplast are exposed to light some electrons gain energy and move from lower energy level higherone ,so the light energy change into potential chemical energy The chlorophyll

Part of the active chlorophyll energy is used in splitting H2O into H + NADP = NADPH2. & O2 releases

The other part of the energy change ADP into ATP

Dark Reaction

(The temperature is the limited factor)

In stroma CO2 is reduced by H2 which is carried on NADPH2 and the energy stored in ATP molecules into carbohydrate

Melvin Calvin experiment

The first stable compound produced during photosynthesis process is PGAL formed of 3 carbon atoms Phosphoglyceraldehide

The importance of PGAL

It is used as the source of energy in cellular respiration -

It store in the form of starch -

It is used in the formation of protein and fats

Heterotrophic nutrination




Digestion: is the conversion of large food molecule or polymers (porteins starch and fats) into smaller ones or monomers (amino acids, glucose, fatty acids and glycerol) in a process catalyzed by enzymes

The enzyme
It is a proteinic substance has the properties of a catalyst & it has a specific ability to activate particular chemical reaction

Types of mechanisms of enzyme action

Breaking down -

Building up -

Properties of enzymes

They are specific in their function -
The enzyme is still as it is at the end of the reaction -
Some enzymes may have a reversible effect -
Enzyme only accelerate’ the rate of the reaction until it reaches a case of equilibrium -
Some enzymes are secreted ‘by the cells in an inactive state -
Enzyme can be used over and over again -
the enzyme is affected by the temperature and PH -

The steps of digestion

Digestion in mouth buccal digestion

In the oesophagus

The oesophagus has glands to secrete mucus only to help in swallow food

Digestion in the stomach gastric digestion




The stomach wall has 2 types of glandular cells that are
cells secretes HCl -
Cells secretes Pepsinogen enzyme -

The functions of HCl

- ( It makes the stomach medium acidic (1.5 : 2.5 PH -

It kills the microbes which enters into the stomach with the food -

it activates Pepsinogen into Pepsin -

Q. Why does not the stomach digest itself

Digestion in the small intestine

A) The bile it is not an enzyme)
The bile emulsifies fats by decreasing its surface tension to increase the area which exposed to the digestive enzyme

The pancreatic juice

NaHCO3 -

Which neutralizes the acidic Chyme & creates an alkaline medium

Pancreatic amylase which hydrolysis the remaining of starch into maltose -

Trypsinogen inactive -
it becomes active by the help of Enterokinase enzyme which is secreted from the ileum

Trypsin hydrolysis the remaining of proteins & converts them into polypeptides

Lipases They hydrolysis emulsified fats into fatty acids & glycerol -

C) The intestinal juice

Peptidases They are a group of enzymes that hydrolysis polypeptides into amino acids -

Enzymes that hydrolysis disaccharides into monosaccharides -

Absorption of digested food

Absorption is the passage of digested food to the blood & lymph through the epithelial cells of the Ileum

The absorbed food passes through 2 routes which are *

Lymphatic route -

The structure of the wall of the small intestine *

Blood route -

Metabolism

It is the process in which the body benefits from the digested -
food which absorbed thorough the digestive system -
Metabolism = Anabolism + Catabolism -

Anabolism
Anabolism is the conversion of small food molecule (monomers) into larger ones called polymers

The sugars change into starch, which stored in the form of glycogen in the liver or muscles -

Amino acids change into protein -

Fatty acids and glycerol change into fats that stored in the body specially the skin -





Catabolism

It is the oxidation process of the absorbed food specially sugar to release the energy that needed by the body to carry out all vital activities

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