Biology: 3. FoodSyllabusOB1 Recall that a balanced diet has six constituents: carbohydrates (including fibre), fats,

proteins, vitamins, minerals and water, each with different functions

OB2 Describe a food pyramid and give examples of types of food recommended in a balanced diet.

OB3 Carry out qualitative food tests for starch, reducing sugar, protein and fat

OB4 Read and interpret the energy values indicated on food labels and compare the energy content per 100 g of a number of foods, and identify the food types on the label that form part of a balanced diet.

OB5 Investigate the conversion of chemical energy in food to heat energy

Student NotesWhy do humans need food?We need food for energy to help us grow and to repair worn down or damaged parts of our bodies.

Balanced Diet

Food is composed of six basic categories, called food types:

1. Carbohydrates 2. Fats 3. Proteins 4. Vitamins 5. Minerals 6. Water

Food Type Functions Common Sources

Carbohydrates e.g. Sugars, starch and fibre

(i) Sugar supplies energy(ii) Starch supplies energy(iii) Fibre prevents

constipation

(i) Sugar: Fruits, Honey(ii) Starch: Bread, Potatoes,

Rice,(iii) Fibre: Green vegetables

Fats Provides energy and insulation

Dairy products

Proteins Growth and repair of cells Meat, Fish, Eggs, Milk, Cheese

Vitaminse.g. Vitamin C, Vitamin D

Vitamin C is for healthy gumsVitamin D is for healthy teeth

Vitamin C: Fruit, Green VegetablesVitamin D: Potatoes, Beans, Milk

MineralsCalcium, Iron

Calcium - strong bones Iron – makes red blood cells

Calcium: Dairy productsIron: Red Meat, Green Vegetables

Water Allows cells to function by dissolving and transporting substances

Can be obtained from special bottles in a shop

A balanced diet contains the right amount of each of the different types of food

A food pyramid helps us to determine the correct amount of each food type to maintain in a balanced diet.

Foods in a food pyramid are classified into five main groups (see diagram)

The bottom foods should be eaten often while those at the top should be eaten sparingly. Failure to eat a balanced diet may cause a person to become overweight, tired, and slow and due to a lack of iron they may result in having a condition called anaemia.

Energy Values

Different foods contain different amounts of energy. These amounts are known as Energy Values.

Energy is measured in Joules (J). However energy values of a food can be measured in Kilojoules per 100 gram.

All foods are supposed to display nutritional information on their packets; the table of information on the right was given on a packet of wheat bran.

Food Tests

Food Tested Chemicals Used Positive ResultStarch Add iodine Turns blue-black

Reducing sugare.g. glucose

Add Benedict’s solution and heat Turns brick-red

Fat Rub food on brown paper Translucent Stain

Protein Add sodium hydroxide and then copper sulfate

Turns purple

To investigate the conversion of chemical energy in food to heat energy

1. Place a burning cream-cracker or peanut under a test-tube containing water.

2. Note the temperature of the water before and after.3. The temperature of the water rises.

Nutritional Information per 100 gEnergy 872 kJ / 206 kcalProtein 15 g

Carbohydrate 26.8 g(of which sugars) 3.8 g

Fat 2.5 g(of which saturates)

0.5 g

Fibre 36.5 gSodium 0.028 g

Biology: 5. The Digestive System

SyllabusOB6 Identify and locate the major parts of the digestive system including the mouth,

oesophagus, stomach, liver, pancreas, small intestine and large intestine, and know their functions.

OB7 Identify molars, premolars, canines and incisors, and describe their functions

OB8 Investigate the action of amylase on starch; name the substrate, product and enzyme

Student NotesDiagram of the human digestive system

Teeth

A full adult set of teeth contains 32 teeth

Part FunctionMouth Physical digestion

Oesophagus Passes food to the stomach by peristalsis

Stomach Physical and chemical digestion

Small intestine(6 metres long)

Chemical digestion and the absorption of nutrients into the blood

Pancreas Contains digestive enzymes

Liver Produces Bile (for the digestion of fats)

Large intestine Absorption of water from the food remains

Rectum The remains of food and water is stored in the rectum.

Tooth FunctionIncisors Biting and cuttingCanines Grasping and tearingPremolars Grinding and crushingMolars Grinding and crushing

Enzymes

A catalyst is a chemical that speeds up a chemical reaction.An enzyme is a biological catalyst.The substance an enzyme acts on is the substrate and the substance formed by the reaction is the product.

Amylase is an example of an enzyme and is used to break down starch into a reducing sugar called maltose.Therefore in this case starch is the substrate and sugar is the product.Amylase is found in saliva.

To demonstrate the action of salivary amylase on starch

1. Add some saliva (which contains the amylase enzyme) to a starch solution which is in a test tube.

2. Heat in a water bath at 37 0C for 10 minutes. 3. The starch should now be converted to a simple sugar called maltose so we need to test

for this.Add some Benedict’s solution and place in boiling water for a few minutes.

4. The contents of the test-tube should turn red, indicating that sugar is present.

Biology: 7. Respiration

SyllabusOB9 Describe the process of aerobic respiration by means of a word equation and understand that aerobic respiration requires the presence of oxygen

OB10 Demonstrate the products of aerobic respiration

OB11 Carry out qualitative tests to compare the carbon dioxide levels of inhaled and exhaled air

OB12 Describe how oxygen is taken into the bloodstream from the lungs and how carbon dioxide is taken into the lungs from the bloodstream during gaseous exchange and how these processes are affected by smoking

Student NotesRespiration

Respiration is not the same as breathing!!

Respiration can be either aerobic or anaerobic. Aerobic respiration requires oxygen while anaerobic does not.Humans and all other animals carry out aerobic respiration while many micro-organisms like yeast carry out anaerobic respiration

Equation for aerobic respiration

Test for CO2

It turns limewater milky.

Test for water It turns anhydrous copper sulphate from white to blue.

To show that there is more carbon dioxide in exhaled air than in inhaled air.

1. Suck air in through the position shown on diagram A and note that the limewater takes a long time before going milky.

2. Replace the limewater and this time exhale air through the top of the tube as shown in diagram B and note that the limewater goes milky quickly.

3. Conclusion: there is more carbon dioxide in exhaled air.

Glucose + oxygen → Energy + carbon dioxide + water

Respiration is the controlled release of energy from food

How does air enter and leave the lungs?

1. The diaphragm contracts (this is you ‘sucking up’), pulling the ribcage down.

2. The ribcage is attached to the lungs and as a result air is taken in when the mouth (or nasal passage) is open.

3. In order to exhale, the diaphragm relaxes, pushing the ribcage up so if the mouth is open air will escape.

Gaseous exchange: How oxygen is taken into the bloodstream and carbon dioxide and water leave the bloodstreamAir passes in and out of the lungs via the trachea (windpipe), The diagram shows tiny air sacs called alveoli. Each alveolus is surrounded by tiny blood vessels called capillaries.Gaseous exchange takes place here.Oxygen passes from the alveoli into the blood which is flowing through the capillaries,Carbon dioxide and water pass in the opposite direction; from the bloodstream back into the alveoli where they are exhaled back out of the body.

The effect of smokingSmoking has many adverse health effects, including cancer, heart disease, pneumonia and bronchitis.It clogs up the hairs in the nose, which reduces their effectiveness to filter incoming dust particles.It also clogs up the alveoli in the lungs, reducing the ability to exchange gases.

Breathing happens when animals take in oxygen and give out carbon dioxide and water

Biology: 14. ExcretionSyllabusOB20 State the function of the urinary system; describe its structure, identifying the bladder,

renal artery, renal vein, ureter, urethra and kidney

OB21 Name the products of excretion: CO2, water and urea

OB22 Describe the function of the skin in the excretion of waste products made in the body

OB23 Recall that waste products are removed from the bloodstream by filtration in the kidneys in the form of urine, which contains urea, water and salts, and that urine is stored in the bladder before being released from the body.

Student Notes

Urea is a nitrogen-containing compound (remember that the air which we breath in is mostly nitrogen).

The urinary system

Function of the different parts of the urinary system

Renal artery

Carries blood from the body to the kidneys to be filtered

Kidney Removes water, salts and urea from the blood to form urineRenal vein Carries filtered blood from the kidneys to the heart

Excretion is the removal of waste products from the body

The products of excretion are carbon dioxide, water, salts and urea

Ureter Tubes which carry urine from the kidney to the bladderBladder Stores urine until it can be released from the bodyUrethra Takes urine from the bladder to outside the body

The Kidneys

The Skin

Waste products are removed from the bloodstream by filtration in the kidneys.The waste product produced in this process is called urine.

Urine contains urea, water and salts

Water and salts are excreted from the skin in the form of

sweat