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TMN3703 EXAM PACK 2023
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TMN3703EXAM
PACK 2023
QUESTIONS AND
ANSWERS
,UNIT 1: The chemistry of life
lipids
minerals carbohydrates proteins
fertilisers
water
nucleic acids
Inorganic compounds Organic compounds
vitamins
The chemistry
of life
• There are seven features that make living organisms different from
non-living things: nutrition, respiration, movement, excretion, growth,
reproduction, irritability.
• Inorganic molecules are molecules that do not contain chains of carbon
atoms. Examples of inorganic molecules are water and mineral salts.
• Water is vital to life.
• Mineral salts are important to plants and animals.
• Overuse of fertilisers can cause a phenomenon called eutrophication.
• Organic molecules contain the element carbon (C), to which hydrogen (H)
and oxygen (O) are joined.
• Carbohydrates, fats and proteins are examples of organic molecules.
• You can test substances for the presence of carbohydrates, fats and proteins
using simple laboratory tests.
• Lipids are important energy sources and also provide insulation below the
skin of mammals.
• An imbalance of the lipids in our bodies can lead to heart disease.
• Enzymes are proteins that function as organic or biological catalysts and
control the speed of chemical reactions in every cell.
• Enzymes work within specific ranges of temperature and pH. They are used
in biological washing powders.
• DNA and RNA are nucleic acids. DNA is found in the nucleus of cells and
forms chromosomes. RNA is found in the nucleolus of cells and in the
cytoplasm. RNA is involved in protein synthesis.
• Vitamins are organic compounds that are essential for the maintenance of
many metabolic activities in the body. Some are fat soluble and others are
water soluble.
• Lack of vitamins can cause deficiency diseases.
, The function of minerals in plants and animals
Mineral Function Deficiency diseases
Nitrogen Essential for the synthesis of amino acids that In humans, retarded growth
(N) form protein Kwashiorkor in young children
Forms part of the nucleotides of DNA and RNA In plants, chlorosis in older
Required for the formation of chlorophyll leaves
Reduced growth of all plant
organs
Sulphur Present in most proteins, In humans, poor growth
(S) co-enzymes and the hormone insulin In plants, chlorosis in young
Promotes root development leaves
Poor root development
Magnesium Essential component of chlorophyll molecules In humans, poor growth
(Mg) Plays a part in muscular contractions and In plants, chlorosis between
functioning of the nervous system veins of older leaves
Activates certain enzymes
Phosphorus Important for bone and teeth formation In humans, rickets,
(P) Part of the energy carrier ATP malfunctioning of muscle and
Important component of DNA and RNA nerves
Found in phospholipids of cell membranes In plants, poor root growth,
brown spots on leaves
Sodium Maintains osmotic and acid-base balance of In humans, hyponatraemia
(Na) body fluids leading to nausea, vomiting,
Necessary for osmoregulation in the kidneys lethargy, coma and death
Necessary for the secretion of HCl in the stomach In plants, reduced plant growth
Necessary for functioning of nerves and muscles
Calcium Found in the middle lamella of plant cell walls In humans, rickets, blood
(Ca) Essential for the structure of bone and teeth clotting delay
Calcium ions needed for blood clotting In plants, chlorosis in young
Plays a part in cell membrane permeability leaves, poor root growth
Iron Essential in chlorophyll synthesis In humans, anaemia
(Fe) Part of haemoglobin in red blood cells (deficiency In plants, chlorosis of leaf veins,
results in anaemia) inhibition of photosynthesis and
Component of electron carriers in respiration and cellular respiration
photosynthesis
Iodine Constituent of the hormone thyroxin that is In humans, cretinism in children,
(I) secreted by the thyroid gland (deficiency causes goitre in adults
goitre)
Potassium Required for growth of flowers and fruit – extra In humans, malfunctioning of
(K) potassium is added to crop plants before they muscle and nerves, cardiac
start to fruit irregularities
Necessary for functioning of nerves and muscles In plants, reduced growth of
flowers and fruits
The biological importance of carbohydrates
Carbohydrates are the most important source of energy in living organisms,
especially glucose and sucrose. Carbohydrates store energy (fuel), for example
starch in plants and glycogen in animals. Some carbohydrates form structural
components of cells, for example plant cell walls are made up of cellulose.
, The biological importance of lipids
Lipids are a very rich source of reserve energy. Lipids form an insulating layer
beneath the skin to retain body heat. Fats form a structural component of cell
membranes (phospholipids). Fats also form the myelin sheath that covers
nerve cells.
The biological importance of proteins
Proteins form part of the building material of cell membranes, chromosomes,
cytoplasm and cell organelles. All enzymes and some hormones, for example
insulin, are made up of protein. Proteins are needed to make the antibodies that
protect your body against bacteria and viruses.
Proteins also provide a reserve energy source, but this is used only when the
body has already used up the available carbohydrates and fats.
Source and functions of the more important vitamins
Vitamin Source Function Deficiency disease
A Carrots Essential for the correct Night-blindness – poor vision
(retinol) Yellow fruit functioning of the eye in dim light
Milk Improves the eye’s Xerophthalmia – cornea
Dairy products adjustment to darkness becomes dry and has small
Liver sores on it
Fresh green
vegetables
D Animal fats and oils Plays a role in bone growth Rickets – bone deformity in
(calciferol) Dairy products Increases calcium and children
(milk, cream, butter, phosphorus absorption Osteomalacia – in adults,
cheese) by the small intestine and bones become soft and
Egg yolk deposition of these salts in fractures may occur
Fish liver oils bone
E Green, leafy Acts as an anti-oxidant – Causes neuromuscular
(tocopherol) vegetables, e.g. prevents cell membrane disorders, e.g. nerve
spinach, lettuce damage degeneration in the hands and
Eggs feet
Wholewheat bread Deficiency is rare
K Green leafy Needed for blood clotting Failure of blood to clot
vegetables, e.g. Bleeding gums and easy
spinach, lettuce bruising of skin
Made by intestinal
bacteria
B3 Whole grains of Part of co-enzymes used in Pellagra – weakness, loss of
(niacin) cereal cellular respiration weight, diarrhoea, irritability
Fish
Liver
Lean meat
C Citrus fruit (oranges, Maintains intercellular Scurvy – bleeding under skin
(ascorbic acid) lemons) substance in bone, cartilage and bleeding gums
Fresh vegetables and dentine Poor healing of wounds,
Guavas Formation of connective degeneration of skin, teeth
Tomatoes tissues, e.g. collagen and blood vessels
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