BIOLOGY NOTES FOR FORM TWO – ALL TOPICS

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NUTRITION

Concepts of Nutrition and food Nutrients

Meaning of nutrition:

Nutrition is the process by which organisms take in and use nutrients.

Nutrients are any substances that nourish an organism.

Food is any material when taken in absorbed and utilized meet requirement of plant and animal body.

The Concepts of Nutrition and Food Nutrients

Explain the concepts of nutrition and food nutrients

FUNCTION OF FOOD

1. Oxidized to release energy
2. Used in growth of cells
3. Used to repair lost cells and tissue

TYPES OF NUTRITION

There are two main types of nutrition: autotrophic nutrition and heterotrophic nutrition.

Autotrophic Nutrition

Is the process by which organisms manufacture their own food from simpleinorganic substances like carbon and hydrogen using either light energy(photosynthesis) or chemical energy (chemosynthesis)

Heterotrophic Nutrition

Is the process in which organisms get nutrients by eating other organisms

The Importance of Nutrition in Living Things

Outline the importance of nutrition in living things

IMPORTANCE OF NUTRITION

1. Prevent diseases
2. Helps growth and development of cells, tissue and organs
3. It helps to repair damaged parts
4. It helps to protect the body against infection and diseases

Nutrition in Mammals, Human Nutrition

Human Nutrition:

Human Nutrition is the provision to obtain the essential nutrients necessary to support life and health.

OR

Are several types of food substances that are needed by the human body for its proper functioning.

The basic food substances include proteins, carbohydrates, lipids, vitamins, minerals, roughage and water.

Different Types of Food Substances and their Functions in Human Body

Identify different types of food substances and their functions in human Body

PROTEINS

These are substances, which contain elements oxygen and nitrogen.

SOURCE OF PROTEINS

Foods such as Meat, liver, eggs, beans, milk, cheese, peas, groundnuts and mushrooms are good sources of protein.

FUNCTION OF PROTEINS

The following are the function of protein

1. It is used in body building
2. Used by body for tissue growth and repair such as healing of wounds and replacement of skin
3. Used as a source of energy, especially when the body lacks carbohydrates and lipids
4. It enables red blood cells to transport oxygen in our bodies

CARBOHYDRATES

Carbohydrates are mainly made of carbon, hydrogen and oxygen

SOURCES OF CARBOHYDRATES

Foods such as maize, rice, bananas, potatoes, cassava, wheat (bread, cake) and yams are rich in carbohydrates.

FUNCTIONS OF CARBOHYDRATES

The following are the function of carbohydrates

1. They are chief source of energy
2. In plants they are stored as starch
3. In animals they are stored as glycogen

LIPIDS

These are compounds of carbon, hydrogen and oxygen. They are insoluble in water. Lipids are made up of fatty acid and glycogen

SOURCES OF LIPIDS

Foods such as fish, nuts, seed oils, avocados and olives are good sources of lipids.

FUNCTIONS OF LIPIDS

1. Lipids are used as a source of energy
2. Protect the organs such as heart and kidneys

VITAMINS

Vitamins are chemical substances in small amounts that are used to maintain the body.

Vitamins can be grouped into two categories: water-soluble and fat-soluble vitamins.

Fat-Soluble Vitamins can be stored in the body. Examples of fat-soluble vitamins are Vitamins A, O, E and K

Water-Soluble Vitamins are not stored in the body. Vitamins B and C are water soluble.Vitamin B is of various forms, namely Vitamin B1, B2, B6 and B12.

SOURCES, FUNCTIONS AND SIGNS OF VITAMIN DEFICIENCIES

MINERALS

Certain mineral elements are vital for the proper functioning of the body. Some are required in relatively large quantities and therefore called macro mineral sand others are required in very small quantities and are referred to as micro

Macro minerals include calcium, phosphates, potassium, iron, zinc, sodiumchlorine and magnesium.

Micro minerals include iodine, fluoride, manganese and copper.

Examples of minerals, their source and their function in the body

ROUGHAGE

– This is dietary fiber that is obtained from the indigestible parts of plants.

SOURCES OF ROUGHAGE

Foods such as fruits, beans, cabbage, spinach, cassava, and whole baked potatoes are good sources of roughage.

FUNCTIONS OF ROUGHAGE

It helps in the passage of food and feces through the gut by aiding contraction of the gut muscles

WATER

This is a compound containing element hydrogen and oxygen

SOURCES OF WATER

Rainfall, Rivers, Springs etc.

FUNCTIONS OF WATER

1. Used in digestion of food
2. Used in transport of material in the body
3. Used as solvent in chemical reaction

The Concept of Balanced Diet in Terms of Food Quality and Quantity

Explain the concept of balanced diet in terms of food quality and quantity

A BALANCED DIET

Meaning of balanced diet:A balanced diet refers to food containing all types of food nutrients in the correct proportions. We should eat a diet low in fats, sugars and salts but high in protein, carbohydrates, vitamins, minerals and roughage. More importantly we should take in large amounts of water.

IMPORTANCE OF A BALANCED DIET

In order for the body to function properly, different food substances are required to do different works for example:

1. Carbohydrates provide energy
2. Vitamins needed to keep the body healthy
3. Minerals are needed for protection against diseases
4. Water is a universal solvent

Nutritional Requirement for Different Groups of People

Explain nutritional requirement for different groups of people

NUTRITIONAL REQUIREMENTS FOR DIFFERENT GROUPS OF PEOPLE

The following nutritional requirement

1. Expectants: There diet should contain more protein and minerals (Calcium (Ca) and Iron (Fe))
2. Lactating Mothers: Their requirements are like those of expectants but in greater amount to feed the body
3. Children: Require a lot of proteins for growth and development of body tissue.
4. The elderly People: They require adequate amounts of vitamins and minerals to maintain their health
5. Sedentary workers: These are individuals who stay in one place for along time while performing their daily occupational activities. Due to their lifestyle and occupation, obesity is increasingly common among them, they limit their intake of food rich in lipids.
6. Sick people: They need special and plenty of nutrients to help recover their health, those who have incurable diseases such as HIV/AIDS should get food that will help them to manage their conditions. They need to take plenty of fruits and water.

Different Types of Nutritional Deficiencies and Disorders in Human Beings

Outline different types of nutritional deficiencies and disorders in human beings

NUTRITIONAL DEFICIENCIES AND DISORDERS

Malnutrition

This is the condition, which occurs when one fails to feed on a balanced diet. It may be too little or eating only one type. These deficiencies and disorders include obesity, rickets, kwashiorkor, marasmus and anorexia nervosa.

Nutritional Disorders

These are conditions of ill health in a person, which arise as a result of lifestyle.

The Causes, Symptoms, Effect and Control Measures of Nutritional Deficiencies and Disorders

Explain the causes , symptoms, effect and control measures of nutritional deficiencies and disorders

Causes of Malnutrition

There three cause of mulnutrition

1. Eating too little
2. Eating too much
3. Eating one type of food

Effects of Malnutrition

1. Excessive feeding causes obesity
2. Under nutrition causes deficiency diseases

CAUSES, SYMPTOMS, EFFECTS AND PREVENTION MEASURES OF

NUTRITIONAL DEFICIENCIES AND DISORDERS IN HUMAN BEINGS

Digestive System in Human

The digestive system of human refers to the human alimentary canal and the organs and glands associated with it.

Parts of the Human Digestive System and their Adaptive Features

Identify parts of the human digestive System and their adaptive features

THE MAIN PARTS OF ALIMENTARY CANAL

The main parts are:- Mouth, Oesophagus, stomach, small intestine, (duodenum and ileum), large intestine (colon) and rectum.

ADAPTATIONS OF STOMACH TO ITS MODE OF FUNCTION

1. Stomach has sphincter muscles to prevent food from flowing back into the oesophagus
2. Stomach has gastric glands, which produce gastric juice for the digestive process.
3. Also in the stomach of a young baby there is renin which coagulates milk
4. Stomachs have mucus which protects it from corrosion by digestive enzymes
5. There is hydrochloric acid for the emulsification of fats and killing of bacteria

ADAPTATIONS OF ILLEUM TO ITS FUNCTIONS

The following are the adaptations of ileum to its mode of functions:-

1. It has secretory glands, which produce digestive enzymes
2. It is connected to the liver by the bile duct which enable the bile to reach ileum
3. It has finger like projections called villi for the absorption of food
4. The ileum is very long to ensure sufficient absorptions of food
5. The villi have large network of blood capillaries for transporting absorbed food to all parts of the body
6. The inner lining of the ileum is folded to increase the surface area for absorption

The Digestion Process in Human Being

Explain the digestion process in process in human being

DIGESTION PROCESS IN HUMAN BEINGS

Digestion is the process by which food is broken down into a form that can be absorbed and used by the body.

Digestion process involves two processes, which are mechanical break down of food and chemical break down of food. The mechanical break down of food takes place in the mouth where the food is chewed by teeth so as to reduce it into small pieces.

Digestive enzymes achieve chemical break down of food. The digested food is absorbed and assimilated in the body.

The digestion process starts in the mouth where food is mechanically broken down by teeth. The presence of food in the mouth stimulates the salivary gland to produce more saliva.

FUNCTIONS OF SALIVA

1. Have salivary amylase enzyme that converts starch into maltose
2. To moisten the food
3. To provide medium for enzyme reactions
4. Have mucus to lubricate food for easy swallowing
5. Saliva consists of Sodium and Calcium salt to ensure alkaline medium for amylase enzyme

Difference Between the Human Digestive System with that of Other Mammals

Compare the human digestive system with that of other mammals

DIFFERENCES BETWEEN HUMAN DIGESTIVE SYSTEM AND RUMINANTS’DIGESTIVE SYSTEM

The ruminants’ digestive system differs from human digestive system in thefollowing ways:

1. Ruminants have more elaborate system to enable cellulose digestion
2. The stomach of ruminants have four chambers (rumen, reticulum,omasum, abomasum)
3. The food is regurgitated, chewed, and again then passed to omasum.

Common Disorders and Diseases of the Human Digestive System

Outline common disorders and diseases of the human digestive System

DISORDERS AND DISEASE OF THE DIGESTIVE SYSTEM

These include diseases and disorders that affect teeth, oesophagus, stomach, small intestine and large intestines

Examples are:- dental caries, heart burn, ulcers, constipation and flatulence.

1. Dental caries This is commonly referred to as tooth decay. It occurs when bacteria destroy the outer part of the tooth.
2. Heart burn Refers to the burning or painful sensation in the oesophagus. It is caused by regurgitation of hydrochloric acid in the stomach which leads to the irritation of oesophagus.
3. Stomach ulcers Refers to the sore in stomach lining. It is caused by erosion of stomach wall due to enzyme reactions.
4. Constipation Refers to the decrease in frequency of formation of stool. It occurs when the stool becomes dry and hard due to excessive water absorption in the colon.
5. FlatulenceThis is caused by excess gas in the digestive tract

Causes, Symptoms, Effects and Control Measures of Common Disorders and Diseases of the Human Digestive System

Explain causes, symptoms, effects and control measures of common disorders and diseases of the human digestive system

SYMPTOMS OF DENTAL CARIES

1. Tooth ache
2. Holes in the teeth

CONTROL MEASURES TO CARIES

1. Regular brushing of teeth
2. Damaged teeth can be filled with artificial crown
3. Minimization of intake of foods rich in sugar
4. Avoid eating very hot or cold foods
5. Have regular dental check ups

SYMPTOMS OF STOMACH ULCERS

1. Burning pain in the stomach
2. Nausea and vomiting
3. Tiredness and weakness
4. Blood in vomit or stool

CONTROL MEASURES TO STOMACH ULCERS

1. Medication
2. Avoid smoking
3. Avoid taking alcohol
4. Avoid eating acidic foods

SYMPTOMS OF CONSTIPATION

1. Lack of bowel movements for two or three days
2. Hard stools
3. The urge to go for long call even after you have just been to the toilet

PREVENTION OF CONSTIPATION

1. Eat enough fibre
2. Drink enough water
3. Exercise regularly
4. Seek medical help

CAUSES OF FLATULENCE

1. Swallowed air
2. Eating food that causes gas such as beans, cabbage, milk and onions
3. Poor absorptions of carbohydrates

SYMPTOMS OF FLATULENCE

1. Abdominal pain
2. The constant urge to pass wind
3. Excessive belching
4. Accumulation of gas in the stomach

PREVENTION OF FLATULENCE

1. Avoid foods that produce gas
2. Chewing food properly
3. Limit the amount of food which are

Nutrition in Plant, Mineral requirement in Plants

Essential Mineral Element in Plant Nutrition

Mention essential mineral element in plant nutrition

The mineral requirement in plant growth are categorized into two groups:

1. Micro nutrients or minerals
2. Macro nutrients

Macro nutrients are minerals that are required in a large quantity for the plant growth.

They include

Nitrogen, phosphorus, potassium, sulphur, sodium, magnesium, carbon, hydrogen,and oxygen.

Micro nutrients; these are nutrients that are required in small amount for the plant growth.

They include; iron, cobalt, fluoride, silicon, iodine, copper and zink

The Roles of Essential Elements in Plant Nutrition

Investigate the roles of essential elements in plant nutrition

The role of essential mineral elements in plant nutrition

Photosynthesis

The Concept of Photosynthesis

Explain the concept of photosynthesis

Photosynthesis is the process where by green plants manufacture their own food by using light energy produced from the sun. photosynthesis takes place in plants especially in leaves so as to make their own food by the presence of different factors.

FACTORS FOR PHOTOSYNTHESIS

Chlorophyll, corbondioxide, sunlight energy, mineral salts, temperature and water.Equation for photosynthesis:

The Structure of the Leaf in Relation to Photosynthesis

Describe the structure of the leaf in relation to photosynthesis

The petiole or leaf stalk attaches the leaf to the branch or stem. It keeps the lamina in position that will enable it to get a maximum amount of sunlight. The lamina has a large surface area, thus maximizes the absorption of light energy and carbondioxide. The lamina is also thin so that carbondioxide and light energy diffuse over a shot distance to reach cells.

The mid rib and veins contain xylem and phloem. Xylem vessels transport water and mineral salt to the leaf. Phloem vessels transport manufactured food to other parts of the plant.

The Process of Photosynthesis

Explain the process of photosynthesis

It takes place inside the cell organelles known as chloroplasts. Photosynthesis takes place in two stages the light stage and the dark stage.

The Importance of Photosynthesis in the Real Life Situation

Outline the importance of photosynthesis in the real life si

Importance of photosynthesis in daily life:

1. All organisms which are heterotrophy depend on autotrophy as source of food.
2. Living organisms depend on oxygen for their aerobic respiration produced during photosynthesis
3. Photosynthesis convert light energy into chemical energy which is used by other organisms
4. Humans depend on photosynthesis for the energy containing fossil fuel which have developed over a millions of year.

Properties of Food Substance

The Basic Food Substances and Their Properties

Mention the basic food substances and their properties

Basic food substances:

1. i. Carbohydrates
2. Protein
3. Lipids

CARBOHYDRATES

Is the kind of food substance nutrients made up of carbon, hydrogen, and oxygen. Example: cassava, maize, rice etc.

TYPES OF CARBOHYDRATES

1. Monosaccharide
2. Disaccharide
3. Polysaccharide

MONOSACCHARIDE:

Monosaccharide is also known as simple sugar. They include glucose, fructose and galactors. These sugars dissolve in water and form sweet solutions. Monosaccharide are reduced sugar. The general formulae for monosaccharide is (CH₂O)n

Where “n” represents a number of carbon atoms and have a value between 3& 6. Example the formulae of glucose is (C₆H₁₂O₆)

Disaccharides:

This is the kind of carbohydrate which is formed when two monosaccharide molecules combine.

Two glucose molecules combine to form maltose. (C₆H₁₂O₆) + (C₆H₁₂O₆) condensation = C₁₂H₂₂O₁₁+ H₂O some disaccharide are reducing sugars example lactose and maltose , other are non reducing sugar example sucrose

Polysaccharides:

Is the type of carbohydrates formed by condensation involving several monosaccharide Example starch, chitin etc

Properties of polysaccharides:

1. They are not soluble in water
2. They are non reducing sugar
3. They are not sweet
4. When put in water they form suspension

Common Reagents and Chemicals used to Determine Food Properties

Identify common reagents and chemicals used to determine food Properties

TEST FOR CARBOHYDRATES

Food Processing, Preservation and Storage

The Concept of Food Processing , Food Preservation and Food Storage

Explain the concept of food processing , food preservation and food storage

Food processing refers to all the ways in which food is treated in order to make it edible, appetizing and safe to eat or to keep it fresh for a long time.

Some of activities involved in food processing are;

1. Picking, sorting and washing fruits and vegetables
2. Cooking by boiling steaming, roasting backing or frying
3. Converting raw materials into other products for example making cheers from milk or sugar from sugar cane

FOOD PRESERVATION

Food preservation refers specifically to the methods of food processing that areused to prevent food from spoiling or going bad

Methods of food preservation

1. Keeping out micro organisms for example by canning or bottling
2. Using high temperature to kill microorganisms that cause spoilage eg.By pasturalization and boiling
3. Using very low temperature to slow down the growth of microorganisms for example refrigeration.
4. Irradiation which is by using radiations such as gamma rays to kill micro organisms
5. Eliminating the moisture that is needed for growth of micro organism for instance by drying, salting, smoking etc
6. Adding chemicals such as salt sugar, carbon monoxide to preventphysical changes in food

FOOD STORAGE

Refers to the methods used to keep or reserve of food for future use. Food storage can be done on a small scale at the family level for example in a family granary or food store. Or large scale for large populations e.g in government stores of grains.