Yr9 Biology - Diet & Exercise (GCSE AQA B1.1.1)

Yr9 Biology - Diet & Exercise (GCSE AQA B1.1.1)

1. A healthy diet contains the right balance of different foods you need and the right amount of energy

   • Carbohydrates
     • gives you energy and build cells
     • sugary + starchy food - potatoes, rice, cereals, pasta, bread, some fruit and veg
   • Fats
     • provide energy and help in building cell membranes
     • dairy, red meats, some poultry and fish
   • Minerals
     • bodily functions
     • iron is good for the blood as its a component a substance that carries oxygen around the body
     • calcium is good for improving the strength of your bones
     • fresh fruits, veg
   • Vitamins
     • good for keeping body healthy - skin, bones and teeth
     • vitamin c helps to make collagen which heals wounds, supports blood vessel walls and forms a base for teeth and bones
     • dairy products, fresh fruit, veg
   • Proteins
     • help body grow, repair itself, release energy and build cells
     • meats, poultry, fish, dairy, eggs, beans
   • Fibre
     • helps you digest food and provides bulk to move food along you tract
     • cereals, fruit, bread, veg
   • Water
     • essential for most chemical reactions, keeps body temp. normal, lubricates and cushions joints, protects spinal cord and sensitive tissue and gets rid of waste through urination, perspiration and bowel movements
   • MALNOURISHED = not balanced diet
     • leads to being underweight or overweight
     • overweight - leads to Type 2 diabetes, heart disease, arthritis, high blood pressure, cancers
     • underweight - leads to organ failure, lack of resistance to infection, deficiency disease, irregular periods

2. Energy Content

   • Energy input > Energy output = gain weight (positive energy + additional energy stored)
   • Energy input < Energy output = lose weight (negative energy + used to meet demand)
   • Energy increase the amount of energy used by the body
   • CALORIES (kcal) = indicator of energy content of food
   • Measure energy in kilo/joules (k/j)
   • METABOLIC RATE = rate of chemical reactions in cells
     • affected (if high) by amount of exercise (very active), size(bigger=more cells=more cell reactions), environment (climate --> altitude=more sweat), genetics, fitness levels, gender (males higher because % muscle tissue to fat is higher), overweight, age (higher if young)
   • CHOLESTEROL = an insoluble substance which we make in our liver from saturated fats (or eggs, meat and dairy) that gets carried around the body in our blood
     • Needed in body for cell membranes, steroid hormones (testosterone), some growth hormones, bile salts
     • When cholesterol is encased in proteins to be transported around the body, it is called lipoproteins (soluble)
       • LDLs = low-density lipoproteins, known as 'bad' cholesterol, raised levels increase risk of heart problems
         • takes cholesterol around the body in the blood to cells from liver --> creates build up on lining of arteries
         • Factors that increase LDL levels
           • Age - over 50s
           • Gender - Male
           • Smokers
           • Type 2 diabetics
           • Overweight/Obesity
           • Genetic predisposition - family history of heart disease
         • Lowering LDL levels
           • lower intake of saturated fats --> causes accumulation of LDL
           • increase intake of monounsaturated fats --> lowers cholesterol a little
           • increase intake of polyunsaturated fats --> lowers cholesterol a lot
       • HDLs = high-density lipoproteins, known as 'good' cholesterol, reduces risk of heart disease
         • takes excess cholesterol back to the liver --> reduces build up on lining of arteries
     • Avoid increasing risk of CardioVascular Disease by maintaining low levels of LDLs and high levels of HDLs
     • SATURATED FATS increase blood cholesterol levels and are in meat, butter and cheese
     • POLY-UNSATURATED FATS even better at reducing cholesterol levels and balancing HDL and LDL levels than mono-unsaturates. Found in corn oil, sunflower oil, margarines and oily fish
     • MONO-UNSATURATED FATS have two useful effects: reduces overall blood cholesterol levels and improves HDL and LDL balance. Found in olives, olive oil, peanuts and margarines