Nutrition and Digestion

Question 1

The basic unit of carbohydrates?

Answer 1

Simple sugars

Question 2

Examples of monosaccharides:

Answer 2

Glucose

Fructose

Galactose

Question 3

Examples of disaccharides:

Answer 3

Lactose

Maltose

Sucrose

Question 4

Examples of polysaccharides:

Answer 4

Starch (a polymer of glucose)

Glycogen (tissues such as liver and muscles)

Question 5

Why can’t our bodies digest cellulose?

Answer 5

Because our gut doesn’t make the enzyme needed to break down the cellulose molecule

Question 6

What is the role of cellulose in our diet?

Answer 6

It forms dietary fibre/roughage which gives the muscles of the cell something to push against as the food is moved through the intestine

This keeps the gut contents moving, avoiding constipation and helping prevent diseases such as colitis and bowel cancer

Question 7

An example of a fat:

Answer 7

Tristearin found in meat

C₅₁ H₉₈ O₆

Question 8

The basic units of lipids?

Answer 8

3Fatty acids and 1glycerol (glycerine)

Question 9

What causes kwashiorkor?

Symptoms:

Answer 9

Protein deficiency

A swollen belly, weight loss, flaky skin, poor muscle growth, and weakness

Question 10

Use of Vitamin A in the body:

Effect of deficiency:

Answer 10

make a light-sensitive chemical in the retina; protects the surface of the eye

Night blindness; damaged cornea

Question 11

Use of Vitamin B1 (thiamine) in the body:

Effect of deficiency:

Answer 11

Cell respiration

Beri-beri (weakening of muscles and paralysis)

Question 12

Use of Vitamin B2 (riboflavin) in the body:

Effect of deficiency:

Answer 12

Cell respiration

poor growth, dry skin

Question 13

Use of Vitamin B3 (niacin) in the body:

Effect of deficiency:

Answer 13

Cell respiration

Pellagra (dry red skin, poor growth and digestive disorders)

Question 14

Use of Vitamin C in the body:

Effect of deficiency:

Answer 14

Needed to make fibres of connective tissue - sticks together cells in the lining surfaces of the body

Scurvy

Question 15

Use of Vitamin D in the body:

Effect of deficiency:

Answer 15

Absorbs calcium and phosphate

Rickets, poor teeth

Question 16

Test for Vitamin C:

Answer 16

Add 1cm³ of DCPIP solution to a test tube
Add a small amount of food sample (as a solution)
A positive test will show the blue colour of the dye disappearing

• If the Vitamin C solution is very concentrated it will take a few drops to remove the colour.
• If the Vitamin C solution is weakly concentrated then a lot of drops are needed to remove the colour.

Question 17

Test for glucose (reducing sugar):

*Sucrose isn’t reducing sugar

Answer 17

Add Benedict’s solution into sample solution in a test tube
Heat at 60 – 70 °c in a water bath for 5 minutes
Take test tube out of the water bath and observe the colour

A positive test will show a colour change from blue (CuSO₄) to brick red (CuO)

Question 18

Test for protein:

Answer 18

Sample: powdered egg white&raquo_space;> dissolve
Add Biuret solution (CuSO₄ + KOH)

Positive test: blue to purple

Question 19

Test for lipids:

Answer 19

The food sample is mixed with 2cm³ of ethanol and shaken until dissolved

The solution is added to a test tube that is ¾ filled with cold water

A positive test will show a cloudy layer at the top of the water and suspension of tiny droplets called an emulsion

Question 20

Measuring the energy content of food:

Improvements:

Variables:

Answer 20

Measure the mass of your food sample

Add the measured amount of water to a boiling tube and place a thermometer in it to find the initial temperature

Place food sample on a mounted needle and set it alight using a burner

Place the burning sample underneath the boiling tube

Calculate the increase in temperature

Energy (J) = mass of water x c (4.2 J⁰C) x change in temperature

Improvements: repeat, test more foods, set up a barrier to reduce heat loss

Control: the mass of food, the SA of food

Question 21

Define digestion:

Answer 21

Digestion is a mechanical and chemical process where large insoluble food molecules are broken down into small, soluble molecules that can be absorbed into the blood

Question 22

Two layers of muscles in the oesophagus:

Answer 22

Circular muscles

Longitudinal muscles

Question 23

Muscle movement to make the oesophagus narrow?

Answer 23

Circular contract

Longitudinal relax

Question 24

Break down of carbohydrates:

Answer 24

Amylase (salivary gland, pancreas):
starch ➡ maltose

Maltase (wall of the small intestine):
maltose ➡ glucose

Question 25

Break down of proteins:

Answer 25

Pepsin (stomach wall):
proteins ➡ peptides

Trypsin (pancreas):
proteins ➡ peptides

Peptidases (wall of the small intestine):
Peptides ➡ amino acids

Question 26

Break down of lipids:

Answer 26

Lipases (pancreas):

lipids ➡ fatty acids and glycerol

Question 27

pH requirement for protease:

Answer 27

Acidic - 2

Question 28

The function of bile:

Answer 28

• Emulsification of large lipid globules into tiny droplets

- Neutralisation of acidic semi-digested food

Question 29

Adaptations of the ileum:

Answer 29

• Length of the small intestine calls for a large SA which is aided by folds.
• The greatest increase is due to the large amounts of villi and microvilli
• Villi contain a network of blood capillaries (quick absorption) and lacteal (for products of fat digestion)
• Surface of the villi is made up of a single layer of epithelial cells (short diffusion distance)
• Mitochondria for active transport
• Villi are in constant motion: contact with the products of digestion and creates a steep conc. gradient for diffusion
• These blood capillaries join together leading up to the hepatic portal vein to the liver

Question 30

Diseases that can be contracted due to obesity

Answer 30

CHD

Diabetes

Question 31

How do you calculate BMI?

Answer 31

Mass in kg/(height in m)²

Question 32

Some bacteria that are transmitted in food and cause diseases:

Answer 32

Salmonella typhi ➡ typhoid fever

Salmonella entrica ➡ salmonellosis

Listeria ➡ listeriosis

Clostridium botulinum ➡ botulism

Question 33

Ways of food preservation:

Answer 33

Salting
Pickling
Pasteurization
Canning
UHT
Irradiation
Drying
Freezing

Question 34

Structure of teeth:

Answer 34

Enamel ➡ Dentine (cytoplasmic strands) ➡ Pulp cavity (blood vessels and nerves) ➡ Root (cement containing fibres attaching to the jawbone)

Question 35

Ways to prevent tooth decay:

Answer 35

• Brushing your teeth (short bristles to reach crevices)
• Dental floss
• Flouride (strengthens the enamel)
• Healthy balanced teeth
• Avoid sugary drinks and sweets

Question 36

How do the bacteria act on your teeth?

• Dental caries
• Periodontal disease - gums become inflamed and so sensitive that they bleed when brushed. can lead to loss of teeth

Answer 36

Plaque (invisible layer) ➡ 24 hrs ➡ (if left on the teeth ) tartar (hard deposit)