Scientific Models
Complementary.
Define the following terms:
- Independent variable
- Dependent variable
- Control variable
- Independent variable: what is changed
- Dependent variable: what is measured
- Control variable: stays the same
What type of molecule is an enzyme?
Protein.
Explain the impact of increased enzyme concentration on the rate of reaction.
Increased enzyme concentration increases the rate of reaction.
Define metabolism. What does it consist of?
The sum of all the biochemical reactions in an organism is called metabolism. It consists of both anabolic and catabolic reactions.
True or False.
Enzymes are can only facilitate catabolic reactions.
False.
They facilitate both catabolic and anabolic reactions.
Define validity.
The extent to which tests measure what was intended; the extent to which data produced from tests and other processes are accurate.
Justify why enzymes are referred to as biological catalysts.
They speed up chemical reactions that occur in living organisms/cells
Describe the changes to an enzyme in a pH environment below its optimum range.
The active site shape changes shape. This prevents the formation of an enzyme-substrate complex.
Which polysaccharide does the enzyme maltose catabolise?
Starch
Name the two models used to describe enzyme action.
1. Lock and key model
2. Induced fit model
Define reliability.
The chances of getting the same/similar result if the experiment was to be repeated
State three features of enzymes.
Any three of:
Explain how temperature affects enzyme activity.
At low temperatures, an increase in temperature increases the rate of an enzyme-catalysed reaction. At high temperatures (past the optimum range) enzyme activity decreases.
Other than enzymes what is another key factor responsible for controlling biochemical processes?
Internal cellular membranes.
Explain the lock and key model.
The active site is highly specific for a particular substrate. The substrate must be of a compatible shape for binding to occur. The substrate fits the active site of the enzyme like a key fits into a lock.
State the type of graph you would draw when the independent variable is discrete.
Bar/Column.
Why do humans and other living organisms require thousands of different enzymes?
There are thousands of different reactions occurring in the human body. Each reaction requires a different enzyme, hence the need for the thousands of different types of enzymes.
Explain the difference between increasing the concentration of enzymes and increasing the concentration of substrates.
If the concentration of the substrate is low, increasing its concentration will increase the rate of the reaction. An increase in the amount of enzyme will increase the rate of the reaction (provided enough substrate is present).
State three means of increasing the validity of scientific experiments.
Any three of:
What is the most widely accepted model of enzyme function? Why?
Induced fit model. Enzymes in this model have broad specificity.
What is the difference between describing a trend and explaining a trend?
Describe - Provide characteristics and features.
Explain - Relate cause and effect; make the relationships between things evident; provide why and/or how
Define ‘activation energy’ and explain how enzymes lower activation energy.
Activation energy is the initial/minimum energy required to start a reaction.
Enzymes weaken/destabilise the bonds within the reactant(s).Therefore, less heat energy from the surroundings is required for bonds to break (in the reactant(s) for the reaction to start.
List at least five factors affecting enzyme action.
1.Concentration of enzyme
2.Concentration of substrate
3.Removal of the products
4.Temperature
5. pH
6.Cofactors (ions or non-protein molecules) or coenzymes (non-protein organic molecules)
7.Enzyme inhibitors
Explain the difference between a human and systematic error.
Human errors are mistakes, for example; incorrectly reading the scale on an instrument. Systematic errors are due to a flaw in the design of the experiment.