Water and Life (part 2)

A set of Question-and-Answer style flashcards covering water properties, cell membranes, chemical reactions, acids/bases, buffers, and blood pH regulation based on the lecture notes.

What happens to water density as it cools until it becomes solid?

It becomes more dense as it cools, until it becomes solid.

Why do water temperature changes occur slowly?

Because water has a high specific heat.

What does it mean that water is polar?

It has an uneven molecular charge distribution and can dissolve other polar substances.

What type of bond is associated with ice (solid water)?

Hydrogen bonds.

Which polar substances can form a solution with water, as mentioned in the notes?

Water and ammonia are polar and can form a water/ammonia solution.

What does 'hydrophilic' mean?

Having an affinity for water; polar substances.

What does 'hydrophobic' mean?

Repels water; non-polar substances.

In a phospholipid bilayer, which part is hydrophilic?

The polar head (outer face).

In a phospholipid bilayer, which part is hydrophobic?

The fatty acid tails.

What membrane components are mentioned?

Cholesterol; integral (intrinsic) proteins; peripheral (extrinsic) proteins.

What types of membrane-associated proteins exist?

Integral (intrinsic) proteins and peripheral (extrinsic) proteins.

What are the reactants in the photosynthesis equation shown?

Carbon dioxide (CO2) and water (H2O).

What are the products in the photosynthesis equation shown?

Glucose (C6H12O6) and oxygen (O2).

What happens to atoms during chemical reactions?

Atoms are rearranged; they are not created or destroyed, forming new substances.

What can accelerate chemical reactions?

Light, heat, or catalysts (enzymes).

What is chemical equilibrium?

Forward and reverse reactions occur at the same rate.

Does chemical equilibrium require equal concentrations of reactants and products?

No; equilibrium means equal reaction rates, not equal concentrations.

How can reactions in biological systems be driven forward?

By removing products, shifting the reaction toward products.

What is the pH of pure water at neutral conditions?

7 (neutral).

How are acids and bases defined in terms of protons?

Acids donate protons (H+); bases accept protons (H+).

What ions result from water autoionization?

Hydronium (H3O+) and hydroxide (OH−).

Why is pure water pH 7 in terms of ion formation?

Because water forms and breaks apart into ions at the same rate.

What is a buffer?

A buffer is a solution with a weak acid and a weak base.

What buffering system is present in human blood?

Carbonic acid (H2CO3) and bicarbonate (HCO3−).

What pH range does the blood buffer maintain?

Between 7.35 and 7.45.

What are acidosis and alkalosis?

Acidosis: pH too low; Alkalosis: pH too high.

Which organs regulate the carbonic acid/bicarbonate buffer system?

Lungs and kidneys.

What is the chemical equation for the carbonic acid-bicarbonate system shown?

CO2 + H2O ⇌ H+ + HCO3− (involving carbonic acid H2CO3 and bicarbonate HCO3−).