Organisation and Digestive System

Question 1

Tissue

Answer 1

Group of cells with similar structure and function working together

Question 2

Organ

Answer 2

Collection of tissues performing specific functions

Question 3

What does the pancreas do?

Answer 3

Makes hormones to control blood sugar

Makes some enzymes that digest food

Question 4

Factors affecting enzyme-controlled reactions

Answer 4

Temperature
Pressure
Concentration of enzyme
Concentration of substrate
Surface area

Question 5

Process of small intestines digestion

Answer 5

small intestine → soluble food molecules absorbed into blood → transported in bloodstream around body
or
small intestine → large surface area, covered in villi and good blood supply with short diffusion distances to blood vessels → muscular walls squeeze undigested food into large intestine → large intestine → water absorbed into blood → material left forms faeces → passed through rectum and anus

Question 6

Carbohydrates

Answer 6

Sugar
Made up of 1 carbohydrate = glucose
Made up of 2 sugar units joined together = simple sugars
Long chains of simple units bonded together = complex carbohydrates
Provide energy for metabolic reactions

Iodine test = starch
yellow/red → blue/black

Benedict’s test = sugars
blue → red

Question 7

Lipids

Answer 7

Fats and oils
C2, H2, O2
Important in cell membranes, hormones and nervous system
Made up of 3 molecules of fatty acids joined to a molecule of glycerol

Ethanol → goes cloudy

Question 8

Proteins

Answer 8

C2, H2, O2, N2
Important for building up of cells and tissues
Basis of all enzymes
Made up of long chains of amino acids
Biuret test turns blue to purple
Amino acids folded, coiled, and twisted to make specific shapes to enable other molecules to fit into the protein
Bonds sensitive to temperature and pH, if they change shape of protein becomes denatured

Question 9

Lock and Key Theory

Answer 9

Lock and key theory

1) Substrate catalysed fits into active site of enzyme
2) Enzyme and substrate bind together
3) Reaction is fast, products released on surface of enzyme where substrate originally lay
4) Substrate splits into products and leave active site

Question 10

What are some types of metabolic reactions?

Answer 10

Building large molecules from smaller ones - e.g. building lipids from fatty acids
Changing one molecule into another - e.g. glucose to fructose
Breaking down large molecules into smaller ones - e.g. breaking down excess amino acids into urea

Question 11

The effect of temperature on enzyme action

Answer 11

Temperature increases:
•long amino acid chains unravel
•shape of active site changes
•substrate no longer fit into active site
•enzyme is denatured
•no longer act as catalyst
•temperature continues rising => death

Question 12

Effect of pH on enzyme action

Answer 12

Change in pH:
•shape of active site depends on forces between different parts of protein molecules
•forces hold chains in place
•change in pH => specific shape of active site is lost
•enzyme no longer acts as catalyst => stop working

Question 13

Digestive Enzymes

Answer 13

carbohydrates ➜ starch and sugars C = amylase ➜ salivary gland & pancreas
breakdown in mouth and small intestine

protein ➜ amino acids C = Protease ➜ stomach, pancreas & small intestine
breakdown in stomach and small intestine

lipids ➜ fatty acids and glycerol C = lipase ➜ pancreas and small intestine
fatty acids and glycerol leave small intestine pass into your bloodstream

Question 14

Bile

Answer 14

Some fats do not mix with digestive liquids
Bile emulsifies fats ➜ breaking up large drops into smaller droplets
Big surface area
Helps lipase breakdown fats more quickly