3.1 Metabolism & Energy (CQ - Exam)

Question 1

Describe the relationship among the following terms: anabolic reactions, catabolic reactions, endergonic reactions, exergonic reactions.

Answer 1

• Anabolic reaction uses energy to build larger molecules from small molecules
• Catabolic breaks down a compound into smaller molecules to release energy
• Endergonic reactions’ products contain more energy than the reactants, the reactions are not spontaneously—they require an input of energy
• Exergonic reactions’ products contain less free energy than the reactants, they are spontaneous and the free energy is released in the form of heat.

Question 2

What is a metabolic pathway, and why are metabolic pathways advantageous to a cell?

Answer 2

• A metabolic pathway is a consecutive series of chemical reactions, each catalyzed by an enzyme.
• provide cells with energy required to carry out their functions.

Question 3

What is a spontaneous reaction? How can you predict if a chemical reaction is spontaneous?

Answer 3

Spontaneous reaction happens on its own and needs very little energy input

Exergonic: Reaction where the reactants have more energy than the products

Requires very little energy
- Heat
- Electron carriers
- ATP

Question 4

Distinguish between oxidation and reduction reactions. Why are these reactions linked?

Answer 4

• An oxidation reaction is when a reactant loses electrons during a reaction. A reduction reaction is when a reactant accumulates electrons during a reaction.
• These reactions are linked because they typically occur together.

Question 5

Why is the recycling of electron carriers and ATP important for the cell?

Answer 5

Recreating those materials would take a lot more energy than just recycling

Question 6

An insecticide blocks a particular enzyme needed to perform a catabolic reaction. Why would such a substance be lethal in sufficient doses?

Answer 6

• If the enzyme in the catabolic reaction were to not work then there would be no catalyzing biochemical reactions that break down larger complex molecules into smaller units.
• Catabolism breaks down substances (high to low energy)
• Goal to release energy
• If it blocks those enzymes, then issues of acquiring energy (ATP) for ourselves would be lethal

Question 7

Why do biologists prefer to use the terms endergonic and exergonic rather than endothermic and exothermic?

Answer 7

Endergonic and exergonic describes all forms of energy. Meanwhile endothermic and exothermic describes heat or thermal energy.