B3 - Organisation and the digestive system Flashcards
What are cells?
The basic building blocks of all living organisms.
What is a tissue?
A group of cells with a similar structure and function.
What is an organ?
Aggregations of tissues performing specific functions.
What is an organ system?
A group organs which work together to form organisms.
What is a muscular tissue?
A tissue that contracts to move whatever it’s attached to.
What is a glandular tissue?
A tissue which makes and secretes chemicals like enzymes and hormones.
What is an epithelial tissue?
A tissue which covers some parts of the body.
What is the order in which food passes through the digestive system?
Mouth > oesophagus > stomach > small intestine > large intestine > rectum >anus
What is the function of the mouth in digestion?
To mechanically break up food into smaller pieces to increase surface area.
What are two functions of saliva in digestion?
To moisten food to allow easier swallowing.
To start chemical digestion by containing salivary amylase.
What is the function of stomach acid?
To kill potentially pathogenic microorganisms in food.
What is the function of the small intestine?
To absorb glucose, amino acids vitamins and mineral ions digested in food.
How are the small intestines adapted to carry out their function?
They have structures called villi which increase surface area.
How are villi adapted to increase absorption?
Large surface area, wall is only one cell thick and large blood supply.
What is the function of the large intestine?
To absorb water from digested food.
What is the function of the liver in digestion?
To produce bile.
What is the function of the gall bladder?
To store bile until it can be released into the small intestine.
What is the function of bile?
Neutralises hydrochloric acid from the stomach.
Emulsifies fats to increase their surface area.
What is the function of the rectum?
To store undigested material before excretion.
What are the products of digestion used for?
Build new carbohydrates, lipids and proteins.
Glucose is used for respiration.
What practical steps are needed for when testing for food molecules present in different foods?
- Break the food up using a pestle and mortar.
- Transfer to a beaker and add some distilled water.
- Stir the mixture.
- Filter the solution using a filter funnel and filter paper to get rid of any solids left.
What reagent is used to test for reducing sugars?
Benedict’s solution.
What additional steps should be taken other than adding Benedict’s solution?
Place the mixture of the solution and food sample in a water bath set about 75°c and leave for about 5 minutes.
What is a positive result for reducing sugars?
Benedict’s solution turns a brick red colour (could also turn yellow/green if there is less sugar)
What reagent is used to test for protein?
Biuret solution
What is a positive result for proteins?
Biuret solution turns pink/purple.
What reagent is used to test for lipids?
Sudan III
What reagent is used to test for starch?
Iodine solution.
What is a positive result for starch?
Iodine solution turns a blue/black colour.
What enzymes are involved with digestion?
Carbohydrase, lipase and protease.
Why are enzymes important in digestion?
They break down large molecules that can’t be absorbed into the blood stream, down into smaller molecules.
What is the function of carbohydrase?
To break down carbohydrates to simple sugars.
What is amylase?
A carbohydrase that breaks down starch.
What is the function of protease?
To break down proteins into amino acids.
What is the function of lipase?
To break down lipids into glycerol and fatty acids.
Where is amylase produced?
Salivary glands, pancreas, small intestine.
Where is protease produced?
Stomach, pancreas, small intestine.
Where is lipase produced?
Pancreas, small intestines.
What two conditions can affect how enzymes work?
Temperate and PH.
What happens as the temperature of an enzyme controlled reaction increases?
The rate of the reaction will also increase, but only until a certain temperature.
Why does the enzyme stop working past a certain temperature?
The enzyme has become ‘denatured’.
What happens when an enzyme becomes ‘denatured’?
The active changes shape, meaning it will no longer compliment the correct substrate.
How does PH affect enzymes?
Enzymes have an optimum PH. Anything above or below this will cause it to become denatured.
