Biology

Biology

INTRODUCTION TO TRANSPORTATION

INTRODUCTION TO TRANSPORTATION
Transport is the movement of substances within an organism.
All living cells require oxygen and food for various metabolic processes.
These substances must be transported to the cells.
Metabolic processes in the cells produce excretory products which should be eliminated before they accumulate.
The excretory products should be transported to sites of excretion.
Organisms like amoeba are unicellular.
They have a large surface area to volume ratio.
The body is in contact with the environment.
Diffusion is adequate to transport substances across the cell membrane and within the organism.
Large multi-cellular organisms have complex structure where cells are far from each other hence diffusion alone cannot meet the demand for supply and removal of substances.
Therefore an elaborate transport system is necessary.

Biology

IMPORTANCE OF VITAMINS, MINERAL SALTS, ROUGHAGE AND WATER IN HUMAN NUTRITION VITAMINS

These are organic compounds that are essential for proper growth, development and functioning of the body
Vitamins are required in very small quantities.
They are not stored and must be included in the diet. Vitamins Band C are soluble in water, the rest are soluble in fat. Various vitamins are used in different ways

Mineral Salts

Mineral ions are needed in the human body
Some are needed in small amounts while others are needed in very small amounts (trace)
All are vital to human health
Nevertheless, their absence results in noticeable mulfunction of the body processes

Biology

DIGESTIVE SYSTEM AND DIGESTION IN HUMANS

DIGESTIVE SYSTEM AND DIGESTION IN HUMANS.
Organs that are involved with feeding in humans constitute the digestive system.

Digestive System and Associated Glands

Human digestive system starts at the mouth and ends at the anus
This is the alimentary canal
Digestion takes place inside the lumen of the alimentary canal
The epithelial wall that faces the lumen has mucus glands (goblet cells)
These secrete mucus that lubricate food and prevent the wall from being digested by digestive enzymes
Present at specific regions are glands that secrete digestive enzymes
The liver and pancreas are organs that are closely associated with the alimentary canal
Their secretions get into the lumen and assist in digestions

Biology

COMMON DENTAL DISEASES

COMMON DENTAL DISEASES

Dental Carries

Dental carries are the holes or cavities that are formed as acid corrodes enamel and eventually the dentine
Dental Carries

Dental carries are the holes or cavities that are formed as acid corrodes enamel and eventually the dentine

Causes

This is caused by bacteria acting on the food left between teeth and on the cusp
Acids are formed that eventually corrode the enamel
The pulp cavity is eventually reached
A lot of pain is experienced then
The bacteria then infect the pulp cavity and the whole tooth decays

This is caused by bacteria acting on the food left between teeth and on the cusp
Acids are formed that eventually corrode the enamel
The pulp cavity is eventually reached
A lot of pain is experienced then
The bacteria then infect the pulp cavity and the whole tooth decays

Biology

ENZYMES

Enzymes are biological catalysts that increase the rate of chemical reaction in the body
They are all produced inside cells
Some are intracellular and they catalyse reactions within the cells
Others are extracellular and are secreted out of the cells where they work e.g. digestive enzymes

Properties of Enzymes

Enzymes are protein in nature
Enzymes are specific to the type of reaction they catalyse
This is referred to as substrate specificity
Enzymes work in very small amounts
They remain unchanged after the reaction
They catalyse reversible reactions
They work very fast (high turnover numbers) e.g. the enzyme catalase works on 600 thousand molecules of hydrogen peroxide in one second

Biology

PROTEINS

Proteins are the most abundant organic compounds in cells and constitute 50% of total dry weight
Proteins are compounds which are made up of carbon, hydrogen, nitrogen, oxygen and sometimes sulphur and phosphorus
The structural units of proteins are amino acids
The nature of a protein is determined by the types of amino acids it is made of
There are about 20 common amino acids that make up proteins

Biology

POLYSACCHARIDES

POLYSACCHARIDES.
If many monosaccharides are joined together through condensation, a polysaccharide is formed.
Polysaccharides may consist of hundreds or even thousands of monosaccharide units
Examples of polysaccharides:
Starch – storage material in plants
Glycogen is a storage carbohydrate in animals like starch, but has longer chains
Isulin – a storage carbohydrate in some plants e.g. Dahlia
Cellulose – structural carbohydrate in plants
Chitin – forms exoskeleton in arthropods

Biology

DISACCHARIDES

Sweet tasting
Soluble in water
Crystallisable
Maltose and lactose are reducing sugars while sucrose is non-reducing sugar
Sucrose is the form in which carbohydrate is transported in plants:
This is because it is soluble andjchernically stable
Sucrose is a storage carbohydrate in some plants e.g sugar-cane and sugar-beet
Disaccharides are hydrolysed to produce monosaccharide units which are readily metabolised by cell to provide energy

Biology

MONOSACCHARIDES

MONOSACCHARIDES
These are simple sugars
The carbon atoms in these sugars form a chain to which hydrogen and oxygen atoms are attached
Monosaccharides are classified according to the number of carbon atoms they possess
The most common monosaccharides are:
Glucose – found free in fruits and vegetables
Fructose – found free in fruits and in bee honey
Galactose – found combined in milk sugar
The general formula for these monosaccharides is (CH2O)n where n is 6
They have the same number of carbon, hydrogen and oxygen molecules i.e C6H12O6

Biology

CHEMICAL COMPOUNDS WHICH CONSTITUTE LIVING ORGANISMS

CHEMICAL COMPOUNDS WHICH CONSTITUTE LIVING ORGANISMS
All matter is made up of chemical elements, each of which exists in the form of smaller units called atoms
Some of the elements occur in large amounts in living things
These include carbon, oxygen, hydrogen, nitrogen, sulphur and phosphorus
Elements combine together to form compounds
Some of these compounds are organic
Organic compounds contain atoms of carbon combined with hydrogen and they are usually complex
Other compounds are inorganic

Biology

ACTIVE TRANSPORT

ACTIVE TRANSPORT
Active transport is the movement of solutes such as glucose, amino acids and mineral ions;
From an area of their low concentration to an area of high concentration
It is movement against a concentration gradient and therefore energy is required
As such it only takes place in living organisms
The energy needed comes from respiration
Certain proteins in the cell surface membrane responsible for this movement are referred to as carrier proteins or channel proteins
The shape of each type of carrier protein is specific to the type of substances conveyed through it
It has been shown that the substance fits into a particular slot on the protein molecule,
As the protein changes from one form of shape to another the substance is moved across and energy is expended

Biology

COMPARISON BETWEEN ANIMAL CELL AND PLANT CELL

Plant Cell & Animal Cell

Cell Specialization

Cells are specialised to perform different functions in both plants and animals

Example;

Palisade cells have many chloroplasts for photosynthesis
Root hair cells are long and thin to absorb water from the soil
Red blood cells have hemoglobin which transports oxygen
Sperm cells have a tail to swim to the egg
Multicellular organisms cells that perform the same function are grouped together to form a tissue
Each tissue is therefore made up of cells that are specialised to carry out a particular function.

Biology

WATER RELATIONS IN PLANT AND ANIMAL CELLS

WATER RELATIONS IN PLANT AND ANIMAL CELLS
The medium (solution) surrounding cells or organisms is described by the terms hypotonic, hypertonic and isotonic
A solution whose solute concentration is more than that of the cell sap is said to be hypertonic

A cell placed in such a solution loses water to the surroundings by osmosis

A solution whose solute concentration is less than that of the cell sap is said to be hypotonic

A cell placed in such solution gains water from the surroundings by osmosis

A solution which has the same solute concentration as the cell sap is said to be isotonic

Biology

THE CELL

THE CELL.

Introduction

The cell is the basic unit of an organism
All living organisms are made up of cells
Some organisms are made up of one cell and others are said to be multicellular
Other organisms are made of many cells and are said to be multicellular
Cells are too little to see with the naked eye
They can only be seen with the aid of a microscope

The microscope

The microscope is used to magnify objects