Biology - B2 Notes

Cell Organisation

• Tissues are groups of similar cells which work together to carry out a particular function
• An organ system is a group of organs that work together to perform a function

The Role of Enzymes and Food Tests

• Enzymes can be described as biological catalysts because they increase the speed of a reaction without being changed or used up in the reaction
• Enzymes only usually catalyse one reaction because of their unique shape and lock and key reaction
• When an enzyme is denatured, it means the bonds holding the enzyme together break at high temperatures or pHs
• pH on the rate of amylase activity - buffer solution experiment
• Amylase is made in the salivary gland, the pancreas, and the small intestine
• Lipases are used to convert lipids into glycerol and fatty acids
• Bile is stored in the gallbladder and neutralises acidic conditions for enzymes
• Lipids can be tested for using Sudan III. If the top layer of the mixture turns bright red, lipids are present

The Lungs and Circulatory System

• The tubes that split off the trachea are the bronchi
• The alveoli contain lots of carbon dioxide and very little oxygen. The blood capillaries that run close to the alevoli let carbon dioxide diffuse into the alveolus and oxygen diffuse out and into the blood capillaries
• The circulatory system is described as a double system because…