Chapter 3: Bio 1

SUJMMERS

How old is the Earth?

4.54 billion years old.

When did life first appear on Earth?

3-4 billion years ago.

When did life become “terrestrial”?

500 million years ago.

What two factors make water an effective solvent?

It has a partial negative and a partial positive charge and it is polar.

What makes a substance hydrophilic?

When it attracts water.

What makes a substance hydrophobic?

When it repels water.

Can a substance be either hydrophilic or soluble?

Yes.

What happens when a water molecule dissociates or ionizes?

It breaks apart to form two specific ions: hydrogen ion (H^+) and hydroxide ion (OH^-).

How does the pH of a solution relate to the [H+] and the [OH−]?

The pH of a solution is determined by the concentration of hydrogen ions and hydroxide ions in a solution.

What is the pH of most biological fluids?

7

What is the pH of most biological cells?

7.0 - 7.4

How do buffers hold the pH steady of both acids and bases?

By neutralizing the pH by adding hydrogen ions or hydroxide ions.

Why must cells maintain and control their pH?

To survive.

What is the expected charge of a biomolecule that’s described as an acid and base?

Acids have a negative charge and bases have positive charges.