IGCSE Biology Paper-1: Specimen Questions with Answers 122 - 122 of 208
Question 122
Question
MCQ▾The figure given below shows the conversion of a substrate into product by an enzyme. In which one of the four option (A-D) the components of reaction labelled as P, Q, R and S are identified correctly.
P | Q | R | S | |
A | Activation energy with enzyme | Transition state | Activation energy without enzyme | Potential Energy |
B | Potential Energy | Transition state | Activation energy without enzyme | Activation energy with enzyme |
C | Transition state | Potential Energy | Activation energy without enzyme | Activation energy with enzyme |
D | Potential Energy | Activation energy with enzyme | Transition state | Activation energy without enzyme |
Choices
Choice (4) | |
---|---|
a. | D |
b. | B |
c. | A |
d. | C |
Answer
b.Explanation
Enzymes Speed up Reactions
The chemical reactions require a certain amount of energy to initiate which is called as activation energy or free energy for the activation. A cell has several substrates, which have average kinetic energy, in which some have higher and some lower than the average energy. In normal temperature, the molecules with high energy react to form the product. This is a slow process. The increase in the reaction rate is due to the raise in the mixture temperature. The heat increases the molecular kinetic energy that causes collisions and reaction between them. Enzyme fastens the reaction as it lowers the required activation energy and allows several numbers of molecules to react at time. It is a known fact that the enzymes have substrate slot where it combines and bring several similar ones closer which collide in the most suitable location and directions where the reaction occurs. The inorganic catalysts work in the same manner. When the substrate binds to the enzymes, there is a conformational change in the enzyme active sites that actually “push” or let a substrate molecule to start an interaction.