Edexcel IGCSE Biology Nutrition

Nutrition In Plants

PHOTOSYNTHESIS

It is the process by which green plants prepare their own food by using water, carbon dioxide in presence of sunlight to form glucose and oxygen.

• Only leaves can photosynthesize as they have chloroplast which contains chlorophyll.
• Chlorophyll is the green pigment that traps light for the leaves and helps them to photosynthesis.
• Photosynthesis is ENDOTHERMIC
• Endothermic as it takes in heat from the sunlight.
• The energy released in making glucose and oxygen is less than the energy required to break the bonds of carbon dioxide and water.

LEAF ADAPTATIONS FOR PHOTOSYNTHESIS

Mesophyll – Photosynthetic cells lies parallel to the surface to absorb maximum light and are closed to the stomata for quick diffusion of gases.

Chloroplast – They have chloroplast which contains chlorophyll and traps light for photosynthesis

Guard cell – They have stomata which are the pores for gas exchange

FACTORS AFFECTING PHOTOSYNTHESIS

• As the light intensity increases the rate of photosynthesis increases and then it levels off.
• Initially the rate increases an€ then it has no effect as at that point other factors become limiting.

• As the light intensity increases the rate of photosynthesis increases and then it levels off.
• Initially the rate increases and then it has no effect as at that point other factors become limiting

• As the temperature increases the rate increases as the particles gain kinetic energy and moves faster causing greater collision and increase reaction rate.
• Beyond optimum the rate decreases as at the higher temperature the enzymes get denatured. The enzyme changes shape and is not functions if the shape changes

LAW OF LIMITING FACTORS

• The factor that limits the rate OF photosynthesis
• Limiting factor is that factor that is present in a least amount than required and affect the rate of photosynthesis.

As the pH increases the rate increases upto optimum. Beyond optimum the rate decreases as enzymes get denatured.

Measuring Photosynthesis

FATE OF GLUCOSE

• Glucose is soluble in water and if present longer will disturb osmotic balance of the cell Starch is complex molecule which is insoluble and can store large amount of glucose.
• Also starch being insoluble does not disturb the osmotic balance of the cell.

GLUCOSE

• Principle source of energy.
• It broken down during respiration and produces energy for the plant to grow and reproduce.

STARCH

• Excess glucose is stored in the plant as starch and is used by the plant when needed.

CELLULOSE

• Excess glucose can be converted into structural carbohydrate called Cellulose
• Cellulose is the component of the cell wall which provide shape and support to the plant.

PROTEINS

• Glucose is combined with nitrates and other mineral ions from the soil to form protein.
• Proteins are responsible for growth and also to make enzymes for metabolic reactions.

LIPIDS

• Glucose can be converted to fats and oil to serve as energy source.
• Fats and oil can form the component of the cell membrane
• They are also stored in seeds as an energy store for germination.

 

TEST FOR STARCH

• Add Iodine Solution
• If the solution turns blue black it indicates the presence of starch.

GREENHOUSE

• It controls all the limiting factors to provide maximum yield of photosynthesize
• Temperature, light, carbon dioxide and other factors affecting photosynthesis are controlled and monitored.
• It works on the principle of greenhouse effect in which light is allowed to enter but is not allowed to escape thereby increasing light and temperature inside the greenhouse.

Nutrition In Animals

LIVING SYSTEM HIEARARCHY

CELLS

• Nerve Cell
• Muscle Cell

TISSUES

• Muscular tissue
• Epithelial tissue
• Glandular tissue

ORGANS

• Stomach, kidney, liver, pancreas, Heart

ORGAN SYSTEM

• Circulatory System,
• Digestive System
• Nervous System
• Excretory System

ORGANISMS

Digestion

It is the process of breaking down large insoluble food particles in the food into soluble small particles which can then be absorbed into the blood

DIGESTION PROCESS

INGESTION –

• It happens with the help of mouth and tongue
• Taking in of food with the help of mouth.
• The teeth and tongue helps in churning the food and mixing with saliva.

DIGESTION –

• It happens with the help of stomach, intestine , pancrease and liver
• Breakdown of large insoluble particle into small soluble ones

ABSORPTION –

• Small Intestine
• The process by which digested food particles are absorbed into the blood

ASSIMILATION –

• In the body cells
• Using the absorbed food for releasing energy and in body processes.

EGESTION –

• By rectum and Anus
• Getting rid of undigested food materials.

BILE JUICE

• It is the green yellow alkaline liquid which is produced in the liver and stored in the Gall Bladder.
• It performs two major Functions:

NEUTRALIZATION

• The food that comes from the stomach is acidic and the enzymes of the intestine can work in alkaline conditions.
• The bile neutralizes the food that comes from the stomach and makes it alkaline so that the enzyme released in the intestine can work effectively.

EMULSIFICATION OF FATS

• For lipase to work, the fat must be broken down into small droplets to increase the surface area for the lipase to function.
• The bile perform this function of emulsification of fats for the efficient working of lipase.

COMPONENTS OF FOOD

Food Component	Source	Monomer	Enzyme	Location	Function
Carbohydrates	Breads, pasta,  Cereals; Rice	Sugars	Carbohydrase  eg Amylase	Mouth and small intestine	Principal source of energy  Fuel for respiration Storage molecules like starch and glycogen Structure molecule like cellulose
Proteins	Pulses, chicken  Meat, poultry Eggs, Beans Nuts	Amino Acids	Protease	Stomach and small intestine	Components of muscles.  Required for growth and repair. components of enzymes Hormones like insulin
Fats	Butter, Oil;  Margarine,	Fatty Acids +  Glycerol	Lipase	Small Intestine	Insulates the body  Reserve source of Energy components of cell membrane