Unit 4 Nutrients (4.1) and Animal Nutrition (4.3)

What you need to know:B4.1 Nutrients1 List the chemical elements that make up carbohydrates, fats, proteins.2 Describe the structure of large molecules made from smaller basic units, i.e.simple sugars to starch and glycogen, amino acids to proteins, fatty acids and glycerol to fats and oils.3 Describe tests for: starch (iodine solution), reducing sugars (Benedict’s solution), protein (biuret test), fats (ethanol).4 List the principal sources of, and describe the importance of: carbohydrates, fats, proteins, vitamins (C and D only), mineral salts (calcium and iron only), fibre (roughage), water.6 Describe the deficiency symptoms for: vitamins (C and D only), mineral salts (calcium and iron only.5 Describe the use of microorganisms in the manufacture of yoghurt.

B4.3 Animal Nutrition1 State what is meant by the term balanced diet and describe a balanced diet related to age, sex and activity of an individual.2 Describe the effects of malnutrition in relation to starvation, coronary heart disease, constipation and obesity.3 Identify the main regions of the alimentary canal and associated organs including mouth, salivary glands, oesophagus, stomach, small intestine: duodenum and ileum, pancreas, liver, gall bladder, large intestine: colon and rectum, anus.4 Describe the functions of the regions of the alimentary canal listed above, in relation to ingestion, digestion, absorption, assimilation and egestion of food.5 Define digestion as the breakdown of large, insoluble food molecules into small, water solublemolecules using mechanical and chemical processes.6 Identify the types of human teeth and describe their structure and functions.7 State the causes of dental decay and describe the proper care of teeth.8 State the significance of chemical digestion in the alimentary canal in producing small, soluble molecules that can be absorbed.9 Define absorption as movement of digested food molecules through the wall of the intestine into the blood.10 Identify the small intestine as the region for the absorption of digested food.

What do you already know?

Nutrition

Define nutrition:

Why is it important?

Nutrients

Composition of Nutrients

What is a polymer?

Complete the diagrams to show the formation of polymers from these monomer units:

What chemical elements make up?a) carbohydrates

b) proteins

c) fats

Phenylalanine is in my favourite food - chocolate! Phenylalanine is a building block for a chemical called dopamine in your brain that makes you feel happy :)Read this article to find out other reasons why chocolate is good for you!http://www.thedailybeast.com/articles/2012/03/28/11-reasons-chocolate-is-good-for-your-health.html

Watch BrainPop “Body Chemistry” and answer the questions

What 4 elements make up most of our body weight?

What is the most abundant molecule in our body?

Name an important property of water and give 2 reasons why we need it.

What is the body’s main source of fuel?

Give some examples of lipids.

What jobs do lipids do in our bodies?

In what ways can too much lipid be bad for you?

What body systems are proteins involved in?

Give some examples of structural proteins.

Test for Starch

(a) Label four test-tubes 1- 4.(b) Put about 20 mm (depth) of 10% glucose solution into tube 1

1% starch solution into tube 2 1% albumen solution into tube 3distilled water into tube 4

(c) To each tube, using a dropping pipette, add three drops of iodine solution. Shake the tube (sideways, not up and down) to mix the contents. Look for any colour changes apart from the yellow colour of iodine itself. Complete the results table below.

Results

Substance Colour change after adding iodine

10% glucose solution

1% starch solution

1% albumen solution

water

Conclusion1. The substances selected for testing are examples of three of the principle chemical substances in cells, sugar (glucose), starch, protein (albumen). With which of these substances did iodine react to give a colour change ? 2. Does your result indicate that there is, for example, no sugar and no protein that willgive a colour change with iodine ? 3. What experiments would you have to carry out in order to give a confident answer toquestion 2 ? 4. Does the result indicate that starch will always react with iodine solution to give acolour change?

5 What was the point of the water in tube 4 ?

Test for reducing sugar (glucose)

a) Half fill a beaker with tap water and place it on a tripod and gauze. Heat thewater with a Bunsen burner. While waiting for the water to boil, carry on with instructions (b) to (d). (b) Label four test-tubes 1-4. 1% starch solution into tube 1 10% glucose solution into tube 2(c) Put 20 mm (depth) of 1% albumen solution into tube 3 water into tube 4

(d) To each tube add about 10 mm Benedict's solution. (e) Place the test-tubes in the beaker of hot water (see Figure on p. 2), and adjust the flame to keep the water just boiling (f) After about 5 minutes, turn out the flame. Place the four tubes in a test-tube rack and compare the colours. Record the results in the table and match the final colours as nearly as possible with crayons.

. Results

Solution Colour change on heating with Benedict’s reagent

Final colour (crayon)

1 1% starch

2 10% glucose

3 1% albumen

4 water

1. What colour change occurred when Benedict’s solution was added to each liquid?

2. The solutions selected for testing are examples of three of the principal chemical substances found in cells: glucose, starch, protein (albumen). With which of these food materials did Benedict's solution give a decisive change on heating?

3. Apart from the colour, what change took place in the consistency of the Benedict'ssolution ? 4. Do your results indicate that any sugar (e.g. sucrose, fructose and maltose) will give the same colour as glucose did when tested with Benedict's solution? 5. Do your results allow you to say that (a) no protein will give a colour change whenheated with Benedict's solution, (b) albumen never reacts with Benedict's solution togive a colour change ? 6. Can you predict that glucose will always give the same result with Benedict's solutionas it did in your experiment ? 7. Why was water included in the test ?

Test for Protein

(a) Label four test-tubes 1-4. 1% starch solution into tube 1 10% glucose solution into tube 2(b) Put about 20 mm (depth) of 1% albumen solution into tube 3 water into tube 4 (c) Pour into each tube, about 5 mm dilute sodium hydroxide. (CARE *) (d) Add to this about 5 mm dilute copper sulphate solution. Shake the tube sideways tomix the contents. (e) Return the tubes to the rack, leave for a few seconds and record the resulting coloursin the table below: Results

Substance Reaction with copper sulphate and

sodium hydroxide (Biuret reagent)

1

2

3

4

* CARE. Sodium hydroxide is caustic and dissolves clothing, skin and bench tops. It isdestructive rather than dangerous so if any is spilt on the bench, neutralize it at once with an equal volume of dilute hydrochloric acid and wipe dry. If spilt on clothing do the same but follow with a wash in as much water as possible. If spilt on the skin do not add acid but wash under the tap until the 'soapy' feeling is removed.

1. The substances you tested are examples of three of the principal types of chemical substances in cells; starch, sugar (glucose), protein (albumen). With which of these samples did the reaction give a purple colour? 2. The substance which gave a purple colour was a single example of its class of substances. Would you expect all other samples of this class to give the same reaction? 3. What was the point of using test-tube 4 with the water? NOTE This test is called the ‘biuret’ test. ‘Biuret’ is the name of the compound which gives the purple colour.

Test for Fats

ALL APPARATUS MUST BE DRY. ALL FLAMES MUST BE EXTINGUISHED. (a) Label four test-tubes 1-4. (b) Into tubes 1 and 2 pour about 20 mm (depth) alcohol (ethanol). (c) To tube 1 add one drop of vegetable oil, and shake the tube sideways until the oildissolves in the alcohol. (d) In tubes 3 and 4 pour about 20 mm water. (e) Pour the contents of tube 1 into tube 3 and the contents of tube 2 into tube 4. (f) Record your results as below:

Result when added to water

1 Oil dissolved in water

3

2 Alcohol alone 4

CLEANING THE TUBES. Keep the oily tubes separate from the others and clean them with hot water and liquid detergent.

1. What was the only difference between the contents of tubes 1 and 2 ? 2. What was the visible difference between tubes 3 and 4 after adding the contents of tubes 1 and 2 to the water in them? 3. How would you attempt to explain the appearance of the liquid in tube 3 ? 4. What difficulties can you foresee in using this test with samples which containboth lipids and water ? Testing for biological molecules in foodsUse the 4 tests above to find out what biological molecules are present in each of the food samples given to you.

Food Results with iodine

Results with Benedict’s

solution

Result with Biuret reagent

Result with ethanol

1. Which foods are a good source of the following?a) carbohydrates

b) proteins

c) fats

Revise the food tests http://lgfl.skoool.co.uk/content/keystage4/biology/pc/modules/digestion/food_tests/index.html in preparation for a quick test next lesson!

DietComplete the table below:

Component Function in our body Source

As a fuel for the process of respiration which releases energy

For growth and to repair damaged tissues, helps build muscle, skin and hair

For insulation, as a long term food store and to make cell membranes

To help food pass through the digestive system

Needed in very small amounts to keep us healthy, e.g. for good eyesight and healthy gums

Needed in very small amounts to keep us healthy, e.g. for strong bones and to make red blood cells

As a solvent, to transport substances around the body and to maintain our body temperature

What extra nutrients do these people need and why?

Deficiency Diseases and MalnutritionDefine:Deficiency disease

Malnutrition

Match the disease to the symptoms and then find out the cause:

Problem Symptoms Cause

Excess weight for age and height. Risk of heart problems.

Wasted muscles,, enlarged liver, flaky skin and brittle hair.

Bleeding gums, flaky skin, poor wound healing.

Pale skin, tiredness, breathlessness, low levels of red blood cells

Poor bone development.

Bacteria produce acid that wears down tooth enamel.

Difficult to go to the toilet.

Headaches and thirst.

kwashiorkor, constipation, anaemia, obesity, tooth decay, rickets, scurvy, dehydration

Would you eat this for breakfast?The following lists show the ingredients in five foods. What do you think these foods are? Would you eat them for breakfast?

FOOD 1:WATER, SUGAR, CELLULOSE, MONOSODIUM GLUTAMATE (E621), CAROTENE (E160 A), LYCOPENE (E160D), RIBOFLAVIN (E101), ASCORBIC ACID (E300), CITRIC ACID (E330), MALIC ACID (E296), OXALIC ACID, FLAVOURINGS

FOOD 2:MYOSIN, ACTOMYOSIN, MYOGLOBIN, COLLAGEN, ELASTIN, AMINO ACIDS, CREATINE, LIPIDS, LINOLEIC ACID, OLEIC ACID, LECITHIN (E322), CHOLESTEROL, SUCROSE, GLUCOSE, PYROLIGNEOUS ACID, PHOSPHORUS, THIAMIN, RIBOFLAVIN (E101), NIACIN (E375), CYNAOCOBALAMIN, PYRIDOXINE, SODIUM CHLORIDE, IRON, MAGNESIUM, POTASSIUM

FOOD 3:LECITHIN S (E322), CEPHALINS, LYSOPHOSPHATIDYL CHOLINES, SPHINGOMYELLINS, CHOLESTEROL, AMINO ACIDS, AVIDIN, LUTEIN (E161B), ZEAXANTHIN, PYRIDOXINE, COBALAMIN, BIOTIN, CHOLECALCIFEROL

FOOD 4:GLUTEN, AMINO ACIDS, AMYLOSE, STARCHES, DEXTRIN, SUCROSE, PENTOSANS, HEXOSANS, MONO-, DI- AND TRI-GLYCERIDES, SODIUM CHLORIDE, PHOSPHORUS, CALCIUM, IRON, THIAMIN, RIBOFLAVIN (E101), NIACIN (E375), PANTOTHENIC ACID, VITAMIN D, METHYL ETHYL KETONE, ACETIC ACID (E260), PROPIONIC ACID (E280), BUTYRIC ACID, VALERIC ACID, CAPROIC ACID, ACETONE, MALTOL (E636), ETHYL ACETATE, ETHYL LACTATE

FOOD 5:WATER, CAFFEINE, METHANOL, ETHANOL, BUTANOL, ETHYL BUTANOL, ACETALDEHYDE, METHYL FORMATE, DIMETHYL SULPHIDE, PROPIONALDEHYDE, PYRIDINE, ACETIC ACID (E260), FURFURAL, FURFURYL ALCOHOL, ACETONE,METHYL ACETATE, FURAL, METHYLFURAN, DIACTYL ISOPRENE

The Human Alimentary Canal

Digestive System Facts

● We eat about 500 kg of food each year. That’s half a ton or a horse!

● We produce 1.5 litres of saliva every day!

● Muscles contract in waves (peristalsis) to move your food down your oesophagus so

food would get to your stomach even if you were upside down!

● An adult stomach can hold 1.2 litres of liquid.

● The acid in your stomach is so strong it can kill bacteria and is of a similar strength to

acid found in industrial metal cleaner!

● The digestive system is about 8m long (about the same length as a bus!).

● Every day 10 litres of digested food, liquids and juices flow through the digestive system

but only 80ml is lost in faeces (poo).

● The average poo is 75% water. The rest is fibre, dead cells and bacteria.

Watch BrainPop: “The Digestive system” and the BBC GCSE “Digestion” Video and make your own notes below:

Try the eChalk “Digestion” activity and label the diagram below:

On the diagram label where each of the following processes occurs - ingestion, egestion, digestion, absorption, assimilation

The parts of the Alimentary Canal

Match the structure to its function:

Teeth and tongue Stores bile produced by liver

Salivary glands Releases gastric juice containing hydrochloric acid and a protease enzyme called pepsin

Amylase Digested food molecules are absorbed into bloodstream here

Oesophagus Carries food from mouth to stomach

Stomach Release saliva containing amylase to break down starch into sugar (maltose)

Hydrochloric acid Break food molecules into smaller pieces to increase surface area for enzyme action

Protease enzyme(pepsin)

Produces enzymes (maltase and lactase) to break down carbohydrates maltose and lactose into glucose.

Duodenum (1st part of small intestine)

Digestion (break down) of food takes place here

Liver Produces green liquid called bile

Gall bladder Contains bile salts to break up large fat droplets into smaller droplets (emulsification) to increase surface area for lipase to work on

Bile duct Increase surface area for absorption of digested food molecules

Bile Kills bacteria

Pancreas Breaks starch into maltose (a type of sugar)

Wall of small intestine

Takes blood with food molecules to the liver

Ileum (2nd part of small intestine)

Breaks down protein. Works best at a low pH.

Villi Bile passes through here from gall bladder to duodenum

Hepatic portal vein Produces alkali liquid containing enzymes (amylase, protease, lipase)

The digestive system: eChalk Bounce Words

1. The colon, appendix and rectum make up the ...2. The duodenum and the ileum make up the ...3. The place where food is cut and ground down into smaller pieces4. Where water is absorbed and faeces are stored5. Joins the mouth to the stomach6. Churns the food and adds acid and digestive enzymes

7. Digested food substances are absorbed into the blood here8. Is also called the gullet 9. Stores excess sugar, makes bile and removes poisons from the blood10. The place where faeces is egested through a sphincter11. Has strong muscular walls which push the food by peristalsis towards the stomach12. Makes insulin and digestive enzymes (amylase, lipase and protease)13. Produces mucus (which helps us to swallow food) and amylase (which catalyses the breakdown of starch). It would be difficult to spit without these!14. Bile is produced by this organ (bile is then stored in the ‘gall bladder’)15. Chewed food from the mouth passes into the ...16. After passing through the oesophagus food enters the ...17. After passing through the stomach food enters the ...18. After passing through the small intestine food enters the ...19. After passing through the large intestine food exits the body via the ...20. This part of the digestive system is around 6 to 7 metres long (or 19 to 23 foot) in the average person

Mechanical and Physical Digestion - TeethLabel the diagrams:

Match the tooth to its description:

Incisors Found behind the canines and are used to grind soft food.

Canines Sharp pointed teeth, which are used to bite and tear food.

Premolars Found behind the premolars and are used to grind hard food.

Molars Small rectangular shaped teeth, used for cutting food.

Chemical Digestion - Enzymes

Complete the table:

Name of enzyme Where is it found? Substrate Products

Amylase

Lipase

Protease

Adaptations of the small intestine for absorption

Complete the table:

Feature How this helps absorption

Very _________ Gives plenty of __________ for digestion and

for ___________________ to occur

Has __________ Give the small intestine a ________ _____________ ____________ (LSA) to increase the rate of absoprtion

Villi contain _____________________

To maintain ____________ _____________ and to carry products of digestion to the rest of the ______

Villi have ___________________ For absoprtion of ___________

Villi have walls only ______ _______ ____________

Short distance for _________________ of digested food

Review

What is the purpose of digestion?

List in order the organs of the digestive system

What are the tests for

a) Starch?

b) Glucose?

Evaluating Visking tubing as a model for a gut

In this practical you can:· observe the properties of Visking tubing· compare the properties of Visking tubing with the properties of a gut

ProcedureSAFETY: Wear eye protection when handling chemicals.

Visking tubing is a fine smooth membrane with small holes in it. These holes are large enough to allow water and other small molecules through. They are too small to allow large molecules

through.

Before you start1. Draw a labelled diagram of the equipment

2. Explain what each part of the apparatus represents:

a. Contents of visking tubing

b. Solution around visking tubing

c. Visking tubing itself

3. Predict what you expect to see when you test the water in the boiling tube for starch and sugar.

Investigationa Set up a boiling tube and four test tubes in a rack.b Set out a dimple tile, with dropper bottles of iodine solution and Benedict’s reagent in your work area.c Collect a model gut made of Visking tubing.d Use syringes to put 5 cm3 of starch suspension and 5cm3 of glucose solution into your model gut.e Rinse the outside of the Visking tubing under the tap then suspend it in your boiling tube as shown in the diagram.

f Use a teat pipette to remove about 1 cm3 of the “gut” contents. Put one drop on the dimple tile, and the rest in a test tube. Then put the teat pipette back into the Visking tubing.g With a second pipette, put water into the boiling tube until its level is the same as the gut contents.h Start a stopclock.i Immediately use the second teat pipette to remove about 1 cm3 of the water. Put one drop on the dimple tile, and the rest in a test tube. Then put the teat pipette back in the water outside the Visking tubing.j Test the drops of liquid in the dimple tile by adding one drop of iodine solution from the dropper bottle. If they turn blue-black, the liquid contains starch.k Test the liquids in the test tubes by adding an equal volume of Benedict’s reagent and then place the test tubes in a beaker of boiling water for 2 to 3 minutes. If they turn orange (or greeny-yellow), the liquid contains glucose.l After 15 minutes, sample the liquids inside and outside the tubing again. Ensure that you have a fresh sample by squeezing the pipette a couple of times to expel the remnants of any earlier sample and to mix the liquids well before sampling.m Test a drop of each liquid with iodine solution and 1 cm3 with Benedict’s reagent as in j and k.n Record your results in the table below.

Results

Result of test with iodine

Result of test with Benedict’s reagent

Does the liquid contain starch?

Does the liquid contain glucose?

Gut contents at beginning

Water around gut at beginning

Gut contents after 15 minutes

Water around gut after 15 minutes

Questions

1 What was the purpose of taking samples from the Visking tubing and surrounding water immediately after water was poured around the tubing?

2 From your results, do you think that starch can get through the holes in the Visking tubing membrane? 3 From your results, do you think that glucose can get through the holes in the membrane?

4 What does this tell you about starch and glucose molecules?

5 How is this length of Visking tubing containing starch and glucose similar to the gut of a multicellular organism?

6 What features of a real gut are missing from this model?Microorganisms and Yogurt Production

Fill in the missing words:

Production of yogurt

Bacteria (usually Streptococcus thermophilus and Lactobacillus bulgaricus) are used to ferment

milk at ________. ___________ _______ is produced. As fermentation progresses, the

______ drops. The lactic acid makes the milk ________________. The temperature is then

____________ to 5oC to prevent further bacterial action.The whole process is carried out in

___________ conditions.

Making Natural Yoghurt: Materials and Ingredients

● Portable hotplate or portable microwave oven

● Thermometer

● 1 teaspoon natural yoghurt to use as a starter culture

● Small saucepan, 500ml beaker (or a plastic bowl if using the microwave oven)

● 250 ml milk

● 1 plastic cup

● Incubator or Thermos flask

Method for Making Natural Yoghurt

1. Pour the milk into the saucepan, beaker or plastic bowl.

2. Heat the milk to 90°C and maintain it roughly at this temperature for 10 minutes.

3. Now allow the milk to cool. When it has reached 40°C, mix in 1 teaspoon of natural yoghurt.

4. Pour the mixture into a plastic cup and incubate it for at least 12 hours at around 30-40°C. If a school incubator is not available a Thermos flask or other insulated container could be used.

5. The mixture should now have a thick consistency and the characteristic smell and

taste of yoghurt.

Questions

Find out why the milk needed to be heated to a certain temperature then cooled to 40°C.

Past Paper Questions