Nutrition And Food Tests Flashcards by Seb McKnight

Main functions of food

Energy

Growth and repair and development

Protection

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Main function of food: energy definition

Food is needed to provide energy to carry out the activities and for reactions of the body to work your muscles and other body organs

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Main functions of food: growth and repair and development definition

In order for your body to grow you need to make new cells. New cells are also needed to replace old or damaged cells. Your body makes these new cells from the chemicals in food

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Main functions of food: protection definition

There are lots of reactions taking place in cells of your body to keep you healthy, keep your body working and protect you against disease. Certain chemicals are needed for these reactions which can only be taken in from the food you eat.

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Balanced diet definition

A diet which contains all essential nutrient groups in the correct proportions

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Unbalanced diet definition

A diet which contains too much of some nutrients and/or too little of others

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7 nutrient groups in biology

Carbohydrates
Proteins
Fats (lipids)
Vitamins
Minerals
Water
Fibre

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What elements do carbohydrates contain

Carbon
Hydrogen
Oxygen

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2 types of carbohydrates

Simple and complex

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Examples of simple carbohydrates include

Fructose in fruit

Lactose in milk

Glucose in milk

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Examples of complex carbohydrates

Starch

Glycogen

Cellulose

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The main function of carbohydrates

Energy

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What energy do sugary carbohydrates provide

Fast release energy source

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What type of energy do starchy carbs provide

Slow release energy source

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………. Taste sweet and are soluble in water

Sugars

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What are sugars made up of

1-2 molecules

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Examples of sugars

Glucose and lactose

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What are more complex carbs made of

Long. Chains of sugar molecules bounded together

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Starch is a very important part of the human diet as it is broken down to ……….. during ……… which is then used in ……….. to release energy.

Glucose

Digestion

Respiration

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What do plants store glucose as

Plants store glucose made in photosynthesis as STARCH.

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In our body’s what is carbs stored as

Glycogen

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What can glycogen be broken down to when are sugar reserves are low

Glucose

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What is glycogen

Glycogen is the storage molecule for glucose in animals.

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Where is glycogen found

In liver and muscle cells

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What is glycogen broken down into when are sugar reserves are low

Glucose which is used in respiration to provide us energy.

What does insulin do

The hormone insulin controls the production of glucose in the body

In plants what role does cellulose have

Cellulose has a structural role as it is found in the cell wall of plants

In animals, humans cannot digest ………., but it still plays an important role in the diet as …….

Cellulose Fibre

What does fibre do

Adds bulk do are food, which helps the muscles in the intestine wall to push food along. Fibre prevents constipation and reduces the risk of colon (large intestine) cancer

What elements do lipids contain

Carbon, Hydrogen Oxygen

Two main types of fat

Unsaturated Saturated

Sources of ‘bad’ fats

Bacon, butter, cheese

Sources of unsaturated fats ‘good’ fats

Avocado, seeds, nuts, oily fish

Lipids are an excellent source of what

Energy (they form a energy store(

Lipids provide …….. the energy per gram of carbohydrates and protein

Double

1g of fat provides approximately

38kj of energy

1g of carb and protein provide

17kj

Lipids provide the Body with

Insulation and protection

What are lipids made up of

3 fatty acids and one glycerol molecule. Therefore when fat is digested it is broken down into fatty acids and glycerol

Protein contains the elements

Carbon, hydrogen, oxygen, nitrogen

Examples of food rich in protein

Lean meat, fish, eggs, beans, tofu, milk

Protein provides the building blocks for

Growth and repair and maintenance of cells

Protein can also act as a secondary source of ……. When reserves of carbohydrates and fat are low

Energy

Proteins are large, ……… molecules consisting of long chains of ……………….

Complex Amino acids

How many types of amino acids are there?

What do all the types of amino acids do

Join to different sequences to produce thousands of different types of proteins

What happens to the protein we eat

Digested into amino acids Amino acids pass through the digestive system into the blood Absorbed into our bodies cells Inside the cells they reassemble into different proteins the body needs

Examples of proteins

Enzymes Haemoglobin Antibodies

If the food to be tested is solid then what must you do

Place sample I’m a pestle and mortar and grind Filter the solution through filter funnel. The filtrate can now be tested for different food groups

The food tests involve adding a chemical known as

A reagent

The reagent changes ………. If a particular biological molecule is present in the food

Colour

Test for starch

Iodine solution detects starch

Starch method

Place small sample of food on a spotting tile Use pipette carefully add drops of iodine to the food sample Record any colour change observed

Iodine colour change

Yellow/brown. To. Blue/black

Test for reducing sugars

Benedict’s solution detects the presence of reducing sugars

Method of Benedict’s test

Prepare food solution (grind food with pestle and mortar. Transfer to test tube and add 2cm cubed of distilled water. Stir with glass rod to dissolve Proceed with test Add 2-3 cm cubed of Benedict’s and carefully shake Place boiling tube in hot water bath for 2-3 mins Record any colour change observed

Benedict’s colour change

Blue to green to brick red precipitate

Test for protein

The Biuret test detects protein

Method of Biuret test

Prepare food solution Add 1cm cubed of dilute sodium hydroxide to food solution Add 3 drops of copper sulfate Shake and carefully mix Record Colour change observed

Biuret change

Pale blue to lilac or purple

Test For fat

The emulsion test

Method of the emulsion test

Cut food into very small pieces Add 2 spatulas of the food sample to a test tube Add 2-3 cm cubed of ethanol to the tube Cover the open end of the tube and shake vigorously Allow to settle Add 2 cm cubed of water to tube Record any observations

If fat is present a …………… appears

Cloudy white emulsion

Obesity cause

Caused by taking in too much energy

Heart disease and strokes cause

By the building up of fatty substances (cholesterol) in walls of the arteries

Type 2 diabetes cause

By poor diet or obesity leading the body being unable to effectively control blood sugar levels

1g of protein provides

17kj

1g of fat provides

38 Kj

1g of carbohydrates provide

17kj

How to find the energy content in food and what do we measure It with

Burn food and use heat energy released to warm a known mass of water. We can measure the energy content in a food with a simple calorimeter

What amount of energy is needed to raise the temp of 1cm cubed of water by 1 degree

4.2 J

Controlled variable examples

Starting temp of water Distance of flame from boiling tube Volume of water in boiling tube Same boiling tube and mounted needle Stirring water before taking temp reading

The biggest source of error in calorimeter is

Unwanted heat loss the the air around the apparatus and the food sample not burning completely

How can more accurate results be obtained for energy in food

Use a bomb calorimeter

How is a bomb calorimeter used

Sample burned in a sealed chamber to reduce heat loss to the environment Sample chamber surrounded by another chamber of water in which temp change is measured Sample burned in pure oxygen to ensure complete combustion