Biology 3- Organisation and the digestive system

What is a catalyst?

A substrate that speeds up the rate of another reaction but is not used up or changed itself.

What is a cell?

Cells are the building blocks of all living things.

What is a tissue?

A group of cells with a similar structure and function.

What is an organ?

An organ is a combination of tissues carrying out a specific function.

What is an organ system?

Organs work together within a system.

What is the purpose of the digestive system?

The purpose of the digestive system is to break down larger molecules into smaller soluble ones.

What organs are in the digestive system?

Tongue, mouth, salivary glands, oesophagus, liver, stomach, gallbladder, pancreas, large intestine, small intestine, anus, rectum

What is the independent variable in the required practical?

The pH of the buffer solution.

What is the dependant variable in the required practical?

The time taken for the reaction to complete.

How do you test for sugar in food?

Benedict’s solution

What is the positive result for sugar?

From being blue-green in colour to yellow-red

How do you test for starch in food?

Iodine

What is the positive result for starch?

A blue-black colour

How do you test for protein in food?

Biuret

What is the positive result for protein?

A pink-purple colour

How do you test for lipids in food?

Sudan III

What is the positive result for lipids?

A bright red colour

What are the steps for the required practical?

1. Place a drop of iodine in each well of he spotting tile
2. Measure 2cm³ of amylase and put it in the test tube
3. Measure 1cm³ of pH buffer solution and add it
4. Leave the solution for 5 mins
5. Add 2cm³ of starch solution and begin the timer
6. Add a drop of the solution into the first well-
7. Continue every 30s until the solution stops changing colour
8. Repeat for the two other pH solutions

What does the enzyme amylase help breakdown?

Starch

What does starch break down into?

Simple sugars

Where is amylase made?

\-Salivary glands

\-Pancreas

\-Small intestine

Where does amylase work?

\-Mouth

\-Small intestine

What does the enzyme protease break down?

Protein

What dies protein break down into?

Amino acids

Where is protease made?

\-Stomach

\-Pancreas

\-Small intestine

Where does protease work?

\-Stomach

\-Small intestine

What does lipase breakdown?

Lipids

what do lipids breakdown into?

Fatty acids and glycerol

Where are lipase made?

\-Pancreas

\-Small intestine

Where do lipase work?

\-Small intestine

What is an enzyme?

A biological catalyst: enzymes speed up chemical reactions without being changed or used up

Describe the lock and key theory.

\-Enzymes have an active site which the substrate (reactants) fit into

\-If the reactants are not the complementary shape, the enzyme will not work for that reaction

Why do enzymes need to be in optimum pH and temperature?

\-In extremes of pH and temperature, the enzyme will denture

\-This means that the bonds holding together the 3D shape of the active site will break and it will deform

\-This means the substrate will not fit into the active site anymore

What is bile used for?

It is an alkaline substance which neutralises the hydrochloric acid in the stomach.

What is the optimum conditions of amylase?

pH 7 and 37°C

What is the optimum conditions of protease?

pH 4-6 and 40°C

What is the optimum conditions of lipase?

pH 5 and 35°C

What are the control variables in the required practical?

\-Time before mixing solutions

\-Volume of amylase/starch/pH buffer