Animal tissues, Organs and Organ systems

Question 1

What is the Human Digestive System

Answer 1

An organ system. The food you eat is large and insoluble and needs to be broken down in order for it to be absorbed by cells.

Question 2

What organs is the Human Digestive System made up of and why?

Answer 2

Glands (salvary glands + pancreas) - which produce digestive juices containing enzymes which break down food.

Stomach - produces hydrochloric acid to kill bacteria and to provide the optimum pH for the protease enzyme to work.

Small intestine - where soluble molecules are absorbed into the blood.

Liver - produces bile (stored in gall bladder) which helps the digestion of lipids.

Large intestine - absorbs water from undigested food to produce faeces, which pass out your body via rectum and anus.

Question 3

What are enzymes?

Answer 3

• Biological catalysts
• Present in many reactions so that they can be controlled
• Can break up large molecules and join small molecules
• They are protein molecules
• Each enzyme has its own uniquely shaped active site where the substrate binds

Question 4

What is the Lock and Key hypothesis?

Answer 4

• The shape of the substrate fits to the shape of the active site, so when they bond it forms an ezyme-substrate complex
• Once bound, the reaction takes place and the products are released from the surface of the enzyme

Question 5

What do enzymes require?

Answer 5

Optimum pH and temperature

temperature - (around 37 celsius)
- when the temperature gets too hot, the bonds in the structure will break which changes the shape of the active site, so the substrate no longer fits. The enzyme denatures and can no longer work.

pH - usually 7
- If the pH is too high or low, the forces that hold the amino acid chains that make up the protein will be affected, which will change the shape of the active site, so the subrate no longer fits. The enzyme denatures and can no longer work.

Question 6

The 3 different types of enzymes:

Answer 6

Carbohydrase - convert carbohydrates and starches into simple sugars

Protease - converts proteins into amino acids

Lipase - converts lipids into fatty acids and glycerol

Question 7

The 4 tests that determine what a solution is made up of:

Answer 7

Benedict’s test - for sugars (turns red)
Iodine test - for starch (turns blue-black)
Biuret test - for protein (turns purple)
Emulsion test or Sudan III test - for lipids

Question 8

What is bile’s roles?

Answer 8

• It is alkaline to neutralise stomach acid to (suit enzyme’s optimum pH)
• Breaks down large drops of fat into smaller ones. The larger surface area allows lipase to work faster.