Biology Notes

Imagine that a researcher tries to reduce the size of an enzyme by removing all the amino acids from the protein except those flanking, and constituting, the active site. Why wouldn't this work?

- The removal of the amino acids may affect the ability of the enzyme to bind to substrates. - Without the additional amino acids, the protein may not fold properly. - The removal of the amino acids will likely affect the shape of the active site.

Suppose that, in a given reaction, the enthalpy (H) increases by 10 units, and the disorder (TS) increases by 12 units. By how many units did the Gibbs free energy change?

-2

As a cat pounces on a mouse, its muscles consume 10 units of potential energy (which the cat previously gained from the food it consumed). However, the pounce itself only required 4 units of kinetic energy. How many units of energy were dissipated as heat?

6

Many cellular processes represent work that requires the expenditure of energy. Which of the actions is not a cellular process that requires the cell to expend energy?

Diffusion of water into cells.

Which of the statements is true about exergonic reactions?

Exergonic reactions are catabolic.

Which of the factors accounts for the higher potential energy of C-C and C-H bonds compared to C-O and H-O bonds?

The C-C and C-H bonds are weak, thus requiring a lot of energy to hold together.

Which of the choices is an example of kinetic energy?

a photon of light

In a reaction, enzymes change the:

activation energy.

Which of the choices is an example of potential energy?

an electrochemical gradient across the cell membrane

Enzymes in your gastrointestinal tract digest your lunch. These chemical reactions are categorized as:

catabolism.

The first law of thermodynamics states that:

energy cannot be created or destroyed.

Of the molecules, which has the greatest chemical potential energy?

glucose

Oak trees are categorized as:

photoautotrophs.

Table sugar can burn in the reaction if ignited: C6H12O6 + 6O2 → 6CO2 + 6H2O and in the process some potential energy of the sugar becomes kinetic energy. Which of the choices represents kinetic energy from this reaction?

the products and their surroundings have more heat

Carbon-carbon covalent bonds, such as the ones in carbohydrates and lipids, are _____ and have _____.

weak; a lot of potential energy