Soil Science: Experiments and Concepts, Schemes and Mind Maps of Earth science

Download Soil Science: Experiments and Concepts and more Schemes and Mind Maps Earth science in PDF only on Docsity!

S.2 BIOLOGY CLASS NOTES

By Kugonza Arthur H

Soil is finely divided material covering the earth crust or surface. It consists of air, water, humus, living organisms, and weathered rocks. Importance of soil  Soil provides nutrients e.g. water and minerals to plants which are the chief producers of food in the environment.  Soil is a habitat (home) for many organisms such as earth worms, termites, bacteria fungi and arthropods.  Soil provides a medium through which man and all other animals dispose of their wastes.  Soil is an important natural resource which provides construction materials, supports agriculture, craft and art materials. SOIL FORMATION It is formed from parent rocks by the process of weathering. This occurs over several years. The process of weathering takes place in three ways;

1. Physical weathering: This occurs in the following ways; i) Alternate heating and cooling of the rocks on exposed mountain sides, causes expansion and contraction which cause the rock to crack and break up. ii) By water; this is where rivers and streams wear away the rocks over which they flow by rolling pebbles and other hard particles on them. iii) During sandstorm when wind blows sand against bare rocks iv) Frosting: frost is weather condition where temperatures fall below 0^0 C, water in cracks freezes and expand, causing the rock to break up. 2. Chemical weathering: This is brought about mainly by the action of water especially rain water on the rocks. As it rains, rain dissolves carbon dioxide in the atmosphere to form weak solution of carbonic acid which when falls on soft rocks for example lime, it dissolves them, this results in the release of mineral elements like calcium, magnesium, Aluminium, etc. which are components of soil. In hot damp conditions (tropics) the constituency of rocks especially those containing iron, oxidizes very quickly. The oxidized rocks disintegrate to form soil. 3. Biological weathering: This is brought about by the action and presence of living organisms on rocks. Certain organisms such as lichens are able to grow on bare rock while other small flowering plants are able to grow between the rock fragments. When these die, they form humus which is a component of soil. Man contributes to biological weathering through direct splitting of rocks during road and house construction and indirectly through cultivation. SOIL PROFILE This is the vertical arrangement of the various soil layers called horizons. It represents the different layers at various stages of soil development. A soil with distinguished soil layers is known as mature and that without clear profile is immature or young. The profile consists of the following: i) Top soil ii) Sub soil iii) Parent or underlying rock

Experiment to determine the percentage of air in the soil Apparatus: Measuring cylinders (2), dry soil sample, water, and glass rod. Method

1. Measure about 50 cm^3 of dry soil in a measuring cylinder and tap the container to level out the soil.
2. Measure 50 cm^3 of water in another measuring cylinder.
3. Add the two together (observe carefully as you pour the water onto the soil)
4. Allow the mixture to stand until no more bubbles appear. Read and record the final level of water plus soil in the measuring cylinder. Calculate the air content in terms of percentage. Example Volume of soil = 50cm^3 Volume of water = 50cm^3 Final volume of water + soil after mixing = 85cm^3 Volume of air in soil (100 - 85) = 15cm^3 Percentage of air = (^) 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑠𝑜𝑖𝑙 𝑢𝑠𝑒𝑑𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑎𝑖𝑟 𝑥 100%

Percentage of air = 1550 𝑥 100%

Percentage of air = 30%

3. WATER Soil water comes from rain. Also some rise up from the ground water by capillary action to replace water lost by evaporation from the surface. It is found as a thin film surrounding the soil particles.

Importance of soil water i) It moistens soil and keeps it humid/moist, making it favorable for survival of micro-organisms. ii) It dissolves mineral salts making them available for plants to take. iii) It dissolves carbon dioxide produced by living organisms to form carbonic acid which causes chemical weathering of rocks. iv) It is a raw material for photosynthesis. v) Water absorbed from the soil allows plant cells to be rigid (turgid), and this is very important for support of the plant, particularly herbaceous plants.

Experiment to determine the percentage of water in a soil sample Apparatus: Evaporating dish, fresh soil, weighing scale and oven or Bunsen burner. Procedure: a) Weigh a clean evaporating dish and record its weigh. (Let the weight be X g). b) Fill the evaporating dish with soil and record the weight of the soil plus the evaporating dish. (Let the weight be Y g). c) Dry the soil by heating it gently over a Bunsen burner flame for about 30 minutes. d) Heating and weighing is repeated until a constant mass is achieved. (Take care not to burn the soil to produce smoke). e) Re-weigh the soil and the evaporating dish. (Let it be Z g). f) Then calculate the water content in the soil sample as shown below; Note: You should cool in a desiccator before weighing. This ensures that no fresh vapour enters the soil. Results: Weight of the evaporating dish= X

Weight of soil + evaporating dish = Y Weight of soil + evaporating dish after heating = Z Weight of soil sample = Y-X Weight of water in the soil sample = Y-Z

Percentage of water = (^) 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑓𝑟𝑒𝑠ℎ 𝑠𝑜𝑖𝑙𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 𝑥 100%

Percentage of air = 𝑌−𝑍𝑌−𝑋 𝑥 100%

4. HUMUS

Humus is decaying plant and animal material- the dead bodies of animals, fallen leaves, dead plants and animal droppings. It is a dark brown, rather sticky material that gives soil its dark colour. For the decay process that form humus to work properly plenty of oxygen is needed. Importance of humus i) Because humus is dark-coloured, soil rich in humus absorbs more heat, and this warmth is useful for the germination of seeds and helps to speed up decomposition, making more humus. ii) It has a high absorptive capacity for water. iii) It forma\s a sticky coat around soil particles and binds several together to form soil clumps. The clumps structure greatly improves the drainage of the soil. iv) Humus retains moisture and minerals in the top soil and so, greatly reduces the effects of drying and leaching (washing of minerals). v) It is a source of nutrients used by plants after it is decomposed. vi) It improves soil aeration. vii) It leads to improvement of activities of soil organisms by providing them with food and shelter. viii) It insulates soil against extreme heat and cold temperatures changes.

Experiment to determine the percentage of humus (organic matter) in the soil Apparatus: Crucible, soil sample, weighing scale, heat source, wire, tripod stand, pipe clay triangle Procedure: a) Weigh a clean empty crucible and record its weight (W g). b) Fill the crucible with soil halfway and record the weight of soil plus crucible on weighing scale (X g). c) Dry the soil by heating it in an oven at 1050 C to constant weight (Y g) - the loss in weight of soil at this temperature is due to the water driven out by evaporation. d) Reweigh the soil and crucible and record the weight. e) Heat the dried soil on a crucible to redness in an oven, then weigh the soil after cooling and record its weight. Repeat this till a constant weight is achieved (Z g). Results: Weight of crucible = W g Weight of crucible + fresh soil = X g Constant weight of soil + crucible after heating at 1050 C = Y g Constant weight of soil + crucible after heating to redness = Z g Weight of fresh soil = X - W

Weight of dry soil = Y - W Weight of dry soil after burning off humus = Z - W Weight of humus = Y - Z g

Percentage of humus = (^) 𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑑𝑟𝑦 𝑠𝑜𝑖𝑙𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 ℎ𝑢𝑚𝑢𝑠 𝑥 100% Percentage of humus = (^) 𝑌−𝑊𝑌−𝑍 𝑥 100%

Procedure i) Collect a hand full of fresh top soil and divide it into 2 equal portions. ii) Sterilize one portion of the soil sample by heating it strongly on a crucible for 30 minutes. Leave it to cool and place it in a muslin bag. iii) Place the remaining portion of the fresh soil sample in another muslin bag. iv) Add equal amounts of lime water or bicarbonate indicator in the test tubes and then suspend the muslin bags with soil in the test tubes as shown in the set up below. v) Allow the test tubes to stand for about 2 days and observe the appearance of lime water or bicarbonate solution. Set up

Observation Lime water turns milky or the bicarbonate indicator solution turns yellow in test tube A but remains clear in test tube B. Conclusion Carbon dioxide was produced in test tube A during respiration indicating the presence of living organisms. Lime water remained clear in test tube B because the living organisms in soil in test tube B were killed by heating. TYPES OF SOIL Soil is grouped basing on size and nature of soil particles. On this basis, there are 3 main types of soil namely: Clay soil, Loam soil and Sand soil.

1. Sandy soils;  Sandy soils contain large space between the particles and these spaces allow water to drain off very quickly.  They have a gritty feel when wet and felt between the thumb and figure.  They contain only very small quantities of water and they may be deficient in calcium and magnesium  They are described as light soils because they are relatively easy to work with. 2. Clay soil:  They have small fine particles i.e. fine texture.  The soil particles in clay are closely parked together leaving very small spaces between them. This causes clay soils to have poor water drainage and also become water logged.  They are difficult to work with and therefore described as heavy soils.  They have a sticky feel when wet. 3. Loam soil: This is a mixture of sand (about40%), silt (about40%), clay (15%), organic matter (1-4%) it has stable crumb structure and is the best for crop production.

Differences between clay and sand soil Clay soil Sand soil

1. Very small air spaces between particles Large air spaces between particles
2. Rich in dissolved salts Poorly dissolved salts
3. Has high water retention capacity Has only very low water retaining capacity
4. Poor drainage i.e. low permeability Very easy drainage i.e. high permeability
5. Water can rise to high level by capillarity Water cannot rise to high level by capillarity
6. More than 30% clay and less than 40% sand More than 70% sand and less than 20% clay

PHYSICAL PROPERTIES OF SOIL

1. Porosity: Sandy soil possess large spaces between the soil particles and so more porous. Clay soils possess very small spaces between the soil particles thus less porous. Loam soil is moderately porous. 2. Air content: Sand contains a lot of air so it is well aerated. This is because it has large spaces existing between the particles. Clay soil contains little air so it is poorly aerated due to presence of small spaces between the particles. Loam soil has varying amounts of air. 3. Drainage of water: Sand has good water drainage so it allows water to pass through it very quickly. Clay soil has poor drainage of water and this makes clay water logged. This can be improved by adding humus to it. Loam drains water moderately. 4. Water retention capacity: This refers to the amount of water soil can hold. Sand soil holds little water so it has a poor water retention capacity. It can be improved by adding humus to it. Humus sticks sand particles together. Clay soil tends to become water logged i.e. it holds a lot of water so has a high water retention capacity. Loam soil holds water moderately but not becoming water logged.

Experiment to compare the drainage and retention of water in sand and clay soils Apparatus  filter funnels,  measuring cylinders,  filter papers

 Equal volumes of dry sand and dry clay soils,  Water and  Beakers Procedure a) Measure an equal volume of each soil sample. b) Fold filter papers properly and put one in each funnel. c) Then place clay soil in the filter paper in one funnel and the sand in the other funnel. d) Place the funnels with their contents over measuring cylinders and at the same time pour an equal volume of water on each of the soil samples as shown in the diagrams.

Observe which soil allows water to drain through quickly. Allow the set up to stand for some time till water stops draining through the soils.

Explanation: Water rises to the greatest height at the nearest stages of the experiment in sand soil because sand has large spaces that enable water to rise more rapidly in the first hours. Clay soil shows the highest rise of water hence the highest water capillarity because it is composed of tiny soil particles which present the large surface area over which water molecules cling. Water rises at a slow rate in clay soil because clay has small air spaces between its particles.

Chemical properties of soil

1. Soil colour This determines the amount of heat that can be trapped in a soil sample. Dark soils retain heat more than light soils. 2. Soil pH This is the degree of acidity or alkalinity of the soil. Most soils in the tropics are acidic but some are alkaline. Soil pH affects the rate at which mineral salts e.g. nitrogen, phosphorous, iron are absorbed by plant roots. Most plants grow best in slightly acidic or neutral soil. An experiment to determine the soil pH Apparatus: Fresh soil sample, Distilled water, Universal solution and Indicator chart. Procedure: i) Place about 3g of soil on petri dish and soak it with universal indicator. Leave it for about 2 minutes. ii) Tilt the petri dish so that the indicator drains out of the soil and then compare the indicator colour with the indicator chat. Alternatively: Soak the soil sample with distilled water. Drain off/filter off the water and test it with the universal indicator solution or universal indicator papers. SOIL EROSION This is the removal or washing a way of top soil by animals, wind or running water. The extent of soil erosion is dependent upon the intensity with which the rain falls and not the amount of water. **Types of soil erosion

1. Sheet erosion:** This is where thin uniform layers of soil are eroded over the whole slope. 2. Rill erosion: This is where water cuts shallow channels called rills. The channels deepen as volume of water run off increases. 3. Gulley erosion: This results from rill erosion when the channels deepen and form galleys. Here a lot of soil is carried a way over greater distances. It is facilitated by careless ploughing (up& down the slope). It may follow tracks made by vehicles and from animals. 4. Splash erosion or raindrop erosion: This occurs when intense raindrops displace soil. 5. Wind erosion: In dry conditions, herds of farm animals trample and compact the soil, causing a layer of dust on top. When wind comes, it can blow away the dust.

**Causes of soil erosion

1. Slopes of land:** The deeper the slope the greater the erosion and this is coupled with the intensity of rain. 2) Over grazing: This is caused by the keeping of many grazing animals on a small area. They finish the grass, i.e. remove the grass cover and open it to water erosion. They trample the soil and make it dusty, thus erosion can take place. 3) Deforestation: leaves reduces intensity at which raindrops reach the ground thus extensive falling of trees in an area removes this cover thus facilitating erosion on slopes. 4) Bush burning: Uncontrolled burning of bushes in dry seasons removes the grass top cover, thus leaving the soil bars for erosion.

5) Poor farming methods: Ploughing: It lessens the soil and destroys its natural structure. Failure to replace humus after successive crops reduces water holding properties, so soil dries easily and can easily be blown away. Ploughing up and down a slope accelerates water erosion. Over cropping ; over use of soil depletes fertility, thus causing loss of plant cover. This leaves the soil bare and so susceptible to erosion. Methods of reducing (preventing) soil erosion a) Contour ploughing: Ploughing a long contours i.e. across a slope and not up and down. It allows furrows to trap water rather than to channel it a way. b) Strip cropping: This consists of alternate bands of cultivated and uncultivated soil, following contours. Untilled soil is covered with grass. By alternating the grass and crops each year, the soil is allowed to rebuild its structure while under grass. c) Terracing: This is cultivation a long contours in horizontal strips supported by stones or walls, so breaking up the step down water rush of the surface run-off. The steeper the slope, the closer the terraces must be. d) Correct crop for soil: Steep slopes which should not be ploughed are covered with pasture crops, their roots hold the soil e) Afforestation: This is the Planting large areas of land with trees. They act as wind brakes, hold the soil together, and prevent raindrops from hitting the soil directly. They conserve water and control flooding. f) Mulching: covering of top soil with plant material e.g. banana leaves, maize stems after harvest, cut grass etc. it protects the top soil and conserves the water in the soil.

Effects of soil erosion (to farmers)  Nutrients and soil organisms are carried a way in the top soil.  The soil left behind is unproductive.  Fields may be cut into irregular pieces by rill and gulley erosion  Floods carry a way or submerge and suffocate crops and soil organisms.

SOIL FERTILITY AND CONSERVATION

Soil fertility Soil fertility refers to the amount of nutrients in the soil that can support the growth of plants. Soil can lose its fertility through the following ways. i) Soil erosion. ii) Leaching ; this is the washing down of soluble minerals from topsoil layers to bottom layers where they cannot be accessed by plants. iii) Soil exhaustion ; this is the depletion/reduction in soil nutrients as a result of monoculture, over cropping, etc. iv) Soil compaction ; this is the hardening of soil on the surface due to action of heavy machinery, movement of animals and man on soil, etc. Soil compaction prevents water from penetrating into the soil. Soil conservation This is the protection and careful management of soil to maintain its fertility. It includes methods of controlling erosion and others such as: Intercropping: Here, plants are alternately planted in a systematic or even random manner e.g. coffee, beans, and banana can be intercropped. Fallowing: Land is left to rest and grow back to bush. Crop rotation: The farmer carefully rotates his crops season after season, so that the plants make different demands on the soil.

Removal of CO 2 from the atmosphere: Green plants remove CO 2 into the atmosphere during the process of photosynthesis. Some of the CO 2 in the atmosphere dissolves in rain water to form carbonic acid. This acid reacts with soil mineral salts to form carbonates. Addition of CO 2 in the atmosphere: i) Combustion (burning): When carbon containing fuels e.g. petroleum, coal, natural gas, fire wood are burnt, CO 2 is released into the atmosphere. Formation of such fuels over millions of years is referred to as fossilization. ii) Respiration in animals and plants. iii) Decomposition of organic matter by bacteria and fungi. During this process, CO 2 is released into the atmosphere.

Nutrition refers to the process by which living organisms obtain, consume and use food substances to maintain their life processes (metabolic processes). These food substances are called nutrients. These nutrients in green plants include; water, mineral salts, carbon dioxide and in animals include; carbohydrates, proteins, lipids, etc. Modes of nutrition Nutrition is broadly classified into two groups namely;

1. Heterotrophic nutrition (nourishment on others).
2. Autotrophic nutrition (self-nourishment). 1. Autotrophic nutrition This is a mode of nutrition where by an organism is able to synthesize its own food from inorganic nutrients using some external source of energy. Such organisms are called Autotrophs. Autotrophic nutrition can be divided into two depending on the external source of energy used to drive there processes; Photosynthesis: This is the type of nutrition where organisms make food with the help of sunlight energy. Examples include; green plants, algae, photosynthetic bacteria. Chemosynthesis: This is where organisms make their own food with the help of energy from specific chemical reactions (oxidation of various inorganic compounds). Examples include; chemosynthetic bacteria. 2. Heterotrophic nutrition This is the mode of nutrition where by organisms obtain their food by feeding on already manufactured organic (food) compounds. Heterotrophs are incapable of making their own food. They include; all animals, fungi, insectivorous plants and most bacteria. **Heterotrophic nutrition is of 5 major types, which include:
3. Parasitism** This is an association between two living organisms of different species in which one organism (parasite) obtains food and shelter from the other organism (host) which instead suffers injury and harm. For examples;  A tape worm in the gut of man  A cow and a tick.  A bedbug and a man. 2. Phagocytosis: This is the process of nutrition where simple cells or unicellular organisms engulf solid food particles. For example amoeba and the white blood cells. 3. Saprophytic/saprotrophic nutrition: Saprotrophic nutrition is a mode of heterotrophic nutrition where an organism feeds on dead decaying matter where by they absorb solutions from this dead decaying matter. Examples include; Mushrooms, mucor, common bread mould. 4. Symbiosis / Mutualism; This is a nutritional relationship between two organisms of different species where both organisms benefit. However, only one organism benefits nutritionally. Examples include;  Fungi and algae (lichen).  Root nodules

The disaccharides have the following properties: i) They are sweeter than monosaccharides ii) They can be crystallized iii) They are soluble in water iv) Do not change the colour of Benedict’s solution when heated with it (apart from maltose)- they are known as non-reducing sugars

v) Can be broken down into simple sugars by dilute mineral acids and enzymes Examples of disaccharides include:

1. Sucrose (present in sugar cane)
2. Maltose (present in germinating seeds)
3. Lactose (present in milk)

iii) Polysaccharides Polysaccharides (poly = many, saccharide = sugar) are complex carbohydrates made up of many units of simple sugars. Properties of polysaccharides include:  Are not sweet  Do not dissolve in water

 Cannot be crystallized  Do not change the colour of Benedict’s solution Examples are: Starch , Glycogen and Cellulose. Functions of carbohydrates i) They provide energy in the body when oxidized during respiration. ii) They are the cheap sources of energy for living things iii) They act as food reserves which are stored within organisms e.g. many plants store food as starch and animals as glycogen. iv) They are important components of body structures e.g. cellulose is a component cell walls, chitin forms exoskeleton of arthropods, and heparin is anticoagulant in mammalian blood. v) They are important for commercial values as they provide raw materials for manufacture of various products such as cellulose provides raw materials for manufacture of paper and textiles. Deficiency of carbohydrates results in a deficiency disease called marasmus. Symptoms of marasmus i) High appetite. ii) Dehydration of the body iii) Growth retardation

iv) Wastage of muscles v) Misery and shrunken appearance

FOOD TESTS ON CARBOHYDRATES

1. Test for reducing sugars The reagent used is Benedict’s solution (blue) or Fehling’s solution (blue). Boiling is required. Procedure Observation Conclusion To 1 cm^3 of food solution, add 1 cm^3 of Benedict’s solution and boil.

Colourless or turbid solution turned to a blue solution, then to a green solution, to a yellow precipitate, to orange precipitate and to a brown precipitate on boiling.

Little/Moderate/Much/Too much; reducing sugars present.

Colourless or turbid solution turned to a blue solution which persists on boiling.

Reducing sugars absent.

Examples of reducing sugars include:

1. Glucose (present in grapes)
2. Fructose (present in many edible fruits)
3. Galactose (present in milk)
4. Maltose (present in germinating seeds)

2. Test for non-reducing sugars procedure Observation conclusion To 1 cm^3 of food solution add 1 cm^3 of dilute hydrochloric acid and boil, cool under water then add 1 cm^3 of sodium hydroxide solution, followed by 1 cm^3 of Benedict’s solution and boil.

Colourless or turbid solution turned to a blue solution, then to a green solution, to a yellow precipitate and to a brown precipitate on boiling.

Little/Moderate/Much/Too much; non-reducing sugars present.

Colourless or turbid solution turned to a blue solution which persists on boiling.

Non-reducing sugars absent.

Note: i) When boiled with dilute HCl, the non- reducing sugars breaks down into the reducing sugars. ii) Sodium hydroxide solution or sodium hydrogen carbonate powder is added to neutralize the acid so that Benedict’s solution can work. Examples of non-reducing sugars are sucrose (present in sugar cane) and lactose (present in milk)

3. Test for starch: The reagent used is iodine which is a brown or yellow solution). Procedure Observation Conclusion To 1 cm^3 of food solution, add 3 drops of iodine solution.

Colourless or turbid solution turned to a black or blue-black or blue solution or brown solution with black specks.

Much/moderate/little starch present.

Colourless or turbid solution turned to a yellow or brown solution.

Starch absent.

PROTEINS

These are food nutrients containing carbon, hydrogen, oxygen and nitrogen and sometimes Sulphur or phosphorus. The smallest and building unit of proteins are called Amino acids. The amino acid molecule can condense to form dipeptide; further condensation gives rise to polypeptide molecule (protein). The amino acids can be differentiated into essential and non-essential amino acids. There are a total of twenty (20) amino acids present thus allowing the formation of a variety of proteins. Types of amino acids i) Essential amino acids: These are amino acids which cannot be synthesized in the body. This means they can only be got from the diet. ii) Non-essential amino acids: These are amino acids that can be synthesized by the body so they are not essential in the diet. Sources of proteins: Food substances rich in proteins are eggs, lean meat, beans, Soya, milk and its products, fish and groundnuts.

TESTS FOR LIPIDS

They are tested for using the emulsion test or the grease spot (translucent spot) test. a) The emulsion test: The reagents used are ethanol and water. Procedure Observation Deduction To 1 cm^3 of food solution, add 1 cm^3 of ethanol and shake. Then add 5 drops of water and shake.

A turbid solution turns to a cream emulsion

Lipids present.

Turbid or colourless solution remains a turbid or colourless solution.

Lipids absent.

b) Translucent spot test: Procedure Observation Conclusion Add 2 drops of test solution on a piece of filter paper, allow to dry and observe under light.

A translucent spot is left on the paper. Lipids present No translucent spot is formed on the paper. Lipids absent.

VITAMINS

These are organic compounds required in small amounts in the diet for the normal functioning of the body. They are designated with alphabetical letters and are classified into two: Water soluble vitamins and Fat soluble vitamins. Water soluble vitamins are those which dissolve in water. They include vitamins B and C. Fat soluble vitamins dissolve in fats but not in water. They include vitamins A, D, E, and K. A table showing vitamins and their deficiency diseases Vitamin Common food source Functions Symptom of deficiency A Retinol

Green vegetables, liver, butter, margarine, egg yolk and carrots

Growth in children, resistance to diseases of eye (night blindness) and respiratory tract and good night(Dim light) vision

Night blindness, frequent cold sore eyes and unhealthy skin.

B 1

Thiamine

Yeast, beans, lean meat, egg yolk, bread and rice husks

Tissue respiration, keeps the heart, nerves and digestive organs healthy

Tiredness, retarded growth in children and poor appetite, constipation (beriberi) B 2 Riboflavin

Yeast, milk, liver, cheese, leafy vegetables.

Tissue respiration, growth and health of skin. Keeps mucus membrane healthy

Retarded growth especially in children, cracks on lips, poor vision and skin disorders B 3 - Nicotinic acid/Niacin

Cereal grains, milk and its products, liver and yeast

Same as B 2 Memory loss & depression (pellagra) B 12 cobamine Beef, kidney, liver, yeast Forms red blood cells Low blood count(Anemia) C Ascorbic acid

Fresh fruits and row vegetables

Development of teeth and bones and normal growth.

Scurvy - Sore gums, poor healing of sores in the gum

D Calciferol

Liver, fish, egg yolk. It is also formed beneath skin of man in sunlight.

Building strong and hard bones and teeth, promotes absorption of phosphorus and calcium in the gut

Weak bones and teeth, rickets in children and dental decay.

E

Tocopherol

All foods Anti-oxidant to prevent excess energy production. Promotes fertility in animals e.g. rats

Sterility (infertility) in some animals like rats.

K- Phyllaquinone Cabbage, spinach Normal clotting of blood Prolonged bleeding.

TEST FOR VITAMIN C :

The reagent used is DCPIP (Dichloro Phenol Indole Phenol). It is a deep blue solution. The sources of vitamin C are fresh fruits e.g. oranges, mangoes, lemon, etc. Procedure Observation Conclusion To 1 cm^3 of DCPIP solution in the test tube, add the food solution drop wise.

The blue DCPIP solution is decolorized or turned to a colourless solution.

Vitamin C present

The blue DCPIP solution remained blue. Vitamin C absent

MINERAL ELEMENTS AND SALTS These are inorganic food constituents required in small amounts but whose deficiency affects the normal functioning of the body leading to deficiency diseases. Mineral salts can be divided into; Essential mineral elements (macro elements): These are mineral elements required in relatively large amounts. They are sodium, potassium, phosphorous, calcium, iron, etc. Non-essential or Trace mineral elements (micro- elements): These are mineral elements required in relatively very small amounts. However, their presence in the diet is of at most importance. They are Zinc, Molybdenum, cobalt, Manganese, etc. A table showing some elements and their deficiency diseases MINERAL ELEMENT

SOURCE IMPORTANCE DEFFICIENCY

Fe Iron

Beef, liver, kidney, G.nuts, beans, eggs, green vegetables.

• It is a constituent of Haemoglobin.

Anemia

• Reduced red blood cell account.
• Reduction in oxygen transportation rate.

Ca Calcium

Vegetables, fish, milk, bread, eggs.

• In blood clotting
• hardening of bones and teeth.

Rickets in children Delay in blood clotting Soft bone, poor skeletal growth. P Phosphorus

Most foods Formation of teeth & bones.

It is not likely for one to be deficient of phosphorus since it is found in most foods. I Iodine

• Iodized salts
• Marine fish

It is a constituent of the growth hormone

Goiter: Swelling of the Thyroid gland. Muscle cramp (sharp pains in muscles). F Fluorine

Drinking water Strong bones and teeth. Weak teeth in children.

K Potassium

Fish, beef, liver, mushrooms

Transmission of nerve impulse along neurons

Muscular cramp

Na sodium

Common salt (NaCl) and cheese

Transmission of nerve impulse along neurons

WATER AND ROUGHAGES/DIETARY FIBRES Water This compound is made of two elements namely Oxygen and Hydrogen. In living things, water forms about 60% of weight Importance of water  The plasma of blood is made up of water.  It’s a universal solvent in which absorbed foods, wastes and hormones are transported around the body in blood.  It participates in many metabolic reactions or processes as a raw materials e.g respiration, photosynthesis, gaseous exchange, digestion, and removal of wastes.