Digestion & Nutrition

Question 1

Nutrients

Question 2

What are Nutrients and it Purposes?

Answer 2

Nutrients are substances found in foods that are needed for the body to develop and function.

The human body can’t make nutrients, so they must be supplied by food which contains nutrients.

The nutrients supply energy, provide materials for growth and maintenance, and control body functions.

Question 3

What are carbohydrates and its functions? Digestion of Carbohydrates

Answer 3

Molecules that consists of carbon, hydrogen and oxygen atoms

Source of energy for the body

Starch -> maltose -> glucose
Monosaccharides
glucose
fructose
galactose
Disaccharide
glucose + fructose = Sucrose
glucose + galactose = Lactose
glucose + glucose = Maltose
Polysaccharide
Starch
Glycogen
Cellulose

Question 4

Test for reducing sugar

Answer 4

Benedict’s Test
Add 2 cm3 of benedict’s solution to 2 cm3 of the sugar solution in a test-tube. Shake the mixture and place the test-tube in a boiling water bath for 2-3 minutes

Remains blue — no reducing sugar is present
Changes from blue to green — little reducing sugar present
Changes from blue to yellow/orange — moderate amount of reducing sugar present
Changes from blue to red/brick red precipitate — large amount of reducing sugar is present

Question 5

Test for starch

Answer 5

Add 2 drops of iodine solution to the sample

Blue-black — starch is present
Yellow-brown — starch is absent

Question 6

What are fats and its functions? Digestion of Fats

Answer 6

Lipids are composed of carbon, hydrogen and oxygen atoms

Storage of energy in the body. The body can use fats as a source of energy but only if carbohydrates and proteins are exhausted.
To provide insulation to the body, preventing heat loss
Found in cell membranes
Provide cushioning for vital organs to protect them
A way to reduce water loss from skin surface

Fats -> Glycerol + Fatty Acids

Question 7

Test for Fats

Answer 7

Ethanol- Emulsion Test
Add 2 cm3 of ethanol to a 2 cm3 of sample solution in a dry test-tube. Shake the mixture thoroughly. Add 2 cm3 of distilled water to the mixture. Shake the mixture again

White emulsion — fat is present
Remains clear — fat is absent

Question 8

What are proteins and its functions? Digestion of Proteins

Answer 8

Proteins are organic molecules made up of carbon, hydrogen, oxygen and nitrogen. Sometimes, suffer is also present

Proteins are important in growth, development and repair of worn out-cells
Used in the formation of antibodies to combat diseases
*Forms enzymes that help the chemical reaction in our body

Protein -> Polypeptide -> Amino Acid

Question 9

Test for Protein

Answer 9

Biuret Test
Add 2 cm3 of sodium hydroxide solution and 2 cm3 liquid sample into a test tube. Shake the mixture.

Mixture turns violet — protein is present
Remains blue — protein is absent

Question 10

Vitamins and Minerals
How they affect our health

Answer 10

Vitamins
Needed in our bodies in small amounts, they help the body to use nutrients efficiently.
Essential for metabolism
Can usually get enough from a balanced diet that includes plenty of fruit and vegetables
There are many types of vitamins, each with their own purpose. e.g Vitamin C promotes wound healing

Minerals
Found in food such as meat, cereals, fish, dairy foods, fruit, veggie and nut
Uses: Zinc, to help heal wounds etc.

Question 10

What are dietary fibres and its functions?

Answer 10

Dietary fibre is made up of cellulose from plant cell walls that your body cannot break down.

It helps the digestive system to move the food we eat through the intestines and push the waste material out of the body

Question 11

Digestion

Question 11

Processes involved in nutrition

Answer 11

Ingestion — Taking in
nutrients by eating or drinking

Digestion — Large food molecules are broken down into simpler molecules that can be absorbed into the body cells

Absorption — Nutrients move from the small intestine into the bloodstream through diffusion

Assimilation — The use of nutrients by cells to provide energy or to make new protoplasm for growth

Egestion — Removal of undigested food from the body

Question 11

What are the organs in the digestive system

Answer 11

Mouth (salivary glands)
Oesophagus *spell
Stomach
Small intestine
Large intestine
Rectum
Anus

Question 12

What is digestion

Answer 12

Digestion is the breakdown of large insoluble food molecule into small water-soluble food molecules so that they can be absorbed into the blood

Question 13

What is physical digestion?

What is chemical digestion?

Answer 13

Mechanical break-down of food into small particles.
Brought down by the action of CHEWING and PERISTALSIS

Chewing in the mouth helps to increase the surface area of the food for enzyme action.

Peristalsis is a series of muscular wave-like contractions that occur along the alimentary canal. It helps to push the food down the gut and also enables food to be mixed with digestive juices.

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Chemical Digestion
Involves the breakdown of large molecules of protein, starch and fats into small soluble molecules.These reactions involve digestive enzymes that act as a catalyst to speed up the reaction.

Question 14

Tell me about digestive enzymes
What are they and its uses

Answer 14

An enzyme is a biological catalyst that speeds up chemical reactions in the body.

Enzymes are large protein molecules with their own specific 3D shapes to increase the speed of specific reactions.

Starch -amylase-> maltose -maltese-> glucose
Protein -protease-> amino acid
Fat -lipase-> fatty acid + glycerol

Question 15

Where does digestion of carbohydrate, protein and fat take place?

Answer 15

Carbohydrate — Mouth & small intestine

Protein — Stomach & small intestine

Fat — Small intestine

Question 16

Where is the duodenum?
Where is the ileum?
Where is the colon?

Answer 16

Duodenum and ileum is at the small intestine
colon is at the large intestine