b3 organisation and digestion Flashcards
What is a tissue?
A group of similar cells working together to perform a specific function (e.g. muscle contraction)
What is an organ?
A group of different tissues working together to perform a specific function (e.g. heart)
What is an organ system?
A group of organs working together to perform a major function (e.g.
What is digestion?
The breakdown of large insoluble molecules into small soluble molecules that can be absorbed.
What is mechanical digestion?
Physical breakdown of food (e.g. chewing)
What is chemical digestion?
Breakdown of food using enzymes (e.g. salivary amylase
What is the role of the stomach in digestion?
Churns food (mechanical digestion) and uses hydrochloric acid and pepsin to break down proteins.
What are the main food groups?
Carbohydrates, proteins, fats
What are carbohydrates broken down into?
Simple sugars (e.g. glucose
What are proteins broken down into?
Amino acids.
What are lipids broken down into?
Fatty acids and glycerol.
How do you test for starch?
Add iodine solution – turns blue-black if starch is present.
How do you test for sugars?
Add Benedict’s solution and heat – turns brick-red if sugar is present.
How do you test for proteins?
Add Biuret solution – turns purple if protein is present.
How do you test for lipids?
Add ethanol
What are enzymes?
Biological catalysts that speed up chemical reactions without being used up.
What is the lock and key model?
Enzymes have an active site that fits a specific substrate (like a key fits a lock).
What factors affect enzyme activity?
Temperature
What happens to enzymes at high temperatures?
They denature (active site changes shape
How do you investigate the effect of pH on enzyme activity?
1) Use amylase to break down starch at different pH levels. 2) Test for starch using iodine solution. 3) Time how long it takes for starch to disappear.
What are the control variables in enzyme experiments?
Temperature
What enzyme breaks down carbohydrates?
Carbohydrase (e.g.
What enzyme breaks down proteins?
Protease (e.g.
What enzyme breaks down lipids?
Lipase (breaks lipids into fatty acids and glycerol).
Where is bile produced and stored?
Produced in the liver, stored in gall bladder
What is the role of bile?
Emulsifies fats (increases surface area) and neutralizes stomach acid.
