Topic 3 Diet and digestion Balanced diet Learning

Topic 3: Diet and digestion

Balanced diet Learning objectives: • Understand what a balanced diet should include • Identify sources and describe functions of the components of a balanced diet • Identify the chemical elements present in carbohydrates, proteins and lipids • Describe the structure of carbohydrates, proteins and lipids

RECAP All living things need nutrition Task: Define nutrition

Definition! Nutrition: obtaining the food necessary (containing raw materials or energy) for growth and tissue repair • Food is used to provide energy. • Green plants make their own food (glucose) using sunlight (photosynthesis). • Animals consume plants or other animals.

Balanced diet Task: A balanced diet consists of: • ? • ?

Balanced diet A balanced diet consists of: • Carbohydrates • Proteins • Lipids (fats and oils) • Minerals (e. g. calcium and iron) • Vitamins (e. g. vitamin A, C and D) • Fibre • Water

Balanced diet A balanced diet consists of: • Carbohydrates • Proteins • Lipids (fats and oils) • Minerals (e. g. calcium and iron) • Vitamins (e. g. vitamin A, C and D) • Fibre • Water Task: Around the room are labels of the different components of a balanced diet. You will be given ‘food’ – place it on the component you think it most significantly contains. Extension: look at where others have placed there ‘food’. Do you agree? If not, move it!

Carbohydrate Source: • Sugars - natural (e. g. fruit and honey) - artificial (e. g. cakes, chocolate, fizzy drinks) • Starch (e. g. potato, rice, bread, pasta) Function: • Main supply of energy • Glucose required for respiration Task: Discuss and try to identify sources and function of carbohydrate

Carbohydrate structure Task: Which elements are found in carbohydrate? Elements: • Carbon • Hydrogen • Oxygen Structure: • Carbohydrates are long chains (polymers) of small sugar molecules (monomers) • Carbohydrate (e. g. starch and glycogen) = polysaccharide (polymer) • Simple sugar (e. g. glucose) = mono saccharide (monomer) one sugar molecule (monomer) carbohydrate molecule (polymer)

Protein Source: • Meat , fish, cheese, eggs, nuts Function: • Growth and repair • Enzymes are proteins Kwashiorkor: protein deficiency Task: Discuss and try to identify sources and function of protein

Protein structure Task: Which elements are found in proteins? Elements: • Carbon • Hydrogen • Oxygen • Nitrogen Structure: • Proteins are long chains (polymers) of small amino acid molecules (monomers) • Protein = polypeptide (polymer) • Amino acid = over 20 different types (monomer) one amino acid (monomer) protein molecule (polymer)

Lipids Task: Discuss and try to identify sources and function of lipids Source: • Fat (A lipid that is solid at room temperature) – e. g. butter, cheese, meat, fish • Oil (A lipid that is liquid at room temperature) – e. g. Olive oil, corn oil, Function: • Long term store of energy • Heat insulation • Protection (particularly around vital organs) • Cell membranes • Note: too many lipids can be unhealthy – linked to heart disease

Task: Which elements are found in lipids? Lipid structure Elements: • Carbon • Hydrogen • Oxygen Structure: • Lipids (polymers) are made of fatty acids and glycerol (monomers) Glycerol (monomer) fatty acids (monomer) lipid molecule (polymer)

Vitamins Vitamin A Source: • Carrots, margarine, butter Vitamin C Source: • Fresh fruit and vegetables Vitamin D Source: • Sunlight Task: Discuss and try to identify sources of the different types of vitamins

Vitamin A Source: • Carrots, margarine, butter Function: • Make a light-sensitive chemical in the retina of the eye Deficiency: • Night blindness – difficult to see in dim light

Vitamin C Source: • Fresh fruit and vegetables Function: • Make fibres of connective tissue Deficiency: • Scurvy – wounds fail to heal, bleeding of gums

Vitamin D Source: • Sunlight Function: • Helps growing bones absorb calcium Deficiency: • Rickets – soft bones

Minerals Calcium Source: • Dairy products (e. g. milk) Iron Source: • Red meat, eggs, spinach Task: Discuss and try to identify sources of the different types of minerals

Calcium Source: • Dairy products (e. g. milk) Function: • Healthy teeth and bones

Iron Source: • Red meat, eggs, spinach Function: • Part of haemoglobin in the red blood cells which function in carrying oxygen Task: Why is pop-eye inaccurate?

Water 60% of body is made up of water Source: • Drinks and food! (cucumbers contain 96% water!) Function: • Medium for chemical reactions and transport.

Fibre Source: • Cellulose (fibre) – plant cell wall – so any plants as food Function: • Humans are not capable of digesting cellulose – its function is to provide roughage (dietary fibre) for the muscles of the digestive system to push against something. • It keeps the gut healthy and avoids constipation.

Balanced diet: Paper 2 Question 1 Practice Task: Complete the Paper 2 Question 1 on balanced diet. PAPER 2 Question 1 requires you to read through some biological information related to the specification. You will then be asked questions on the information, which will require comprehension skills combined with application of knowledge.

Key word bingo Task: Draw a box as shown. Select 4 key words. Cross off your word if it is defined. Carbohydrates Oils Vitamin C Iron Insulation Rickets Lipids Protein Vitamin D Water Energy Night blindness Fats Vitamin A Calcium Fibre Growth Scurvy

Thumbs up or down Learning objectives: • Understand what a balanced diet should include • Identify sources and describe functions of the components of a balanced diet • Identify the chemical elements present in carbohydrates, proteins and lipids • Describe the structure of carbohydrates, proteins and lipids