ZOL2601
ASSIGNMENT 2 SEMESTER 1 2026
UNIQUE NO. 841505
DUE DATE: 23 MARCH 2026
, Comparative Animal Physiology - ZOL2601
Assessment 2
Question 1
Various environmental factors influence the amount of gas that can dissolve in water.
The four main factors include temperature, pressure, salinity and gas composition.
1. Temperature
Temperature has an inverse relationship with gas solubility. As temperature
increases, the amount of gas that dissolves in water decreases. Warmer water therefore
contains less dissolved oxygen than colder water. This occurs because increased
molecular movement allows gas molecules to escape from the liquid more easily.
2. Pressure
Gas solubility increases with increasing pressure. According to Henry’s Law, the
amount of gas that dissolves in a liquid is directly proportional to the partial pressure of
that gas above the liquid. Therefore, at higher altitudes where atmospheric pressure is
lower, less oxygen dissolves in water.
3. Salinity
Increasing salinity reduces the solubility of gases in water. Dissolved salts occupy
space and interact with water molecules, making it more difficult for gases such as
oxygen to dissolve. As a result, freshwater typically contains more dissolved
oxygen than seawater under the same conditions.
4. Gas Composition (Partial Pressure)
The concentration of a gas dissolved in water depends on the partial pressure of that
gas in the surrounding atmosphere. If the partial pressure of oxygen increases, more
ASSIGNMENT 2 SEMESTER 1 2026
UNIQUE NO. 841505
DUE DATE: 23 MARCH 2026
, Comparative Animal Physiology - ZOL2601
Assessment 2
Question 1
Various environmental factors influence the amount of gas that can dissolve in water.
The four main factors include temperature, pressure, salinity and gas composition.
1. Temperature
Temperature has an inverse relationship with gas solubility. As temperature
increases, the amount of gas that dissolves in water decreases. Warmer water therefore
contains less dissolved oxygen than colder water. This occurs because increased
molecular movement allows gas molecules to escape from the liquid more easily.
2. Pressure
Gas solubility increases with increasing pressure. According to Henry’s Law, the
amount of gas that dissolves in a liquid is directly proportional to the partial pressure of
that gas above the liquid. Therefore, at higher altitudes where atmospheric pressure is
lower, less oxygen dissolves in water.
3. Salinity
Increasing salinity reduces the solubility of gases in water. Dissolved salts occupy
space and interact with water molecules, making it more difficult for gases such as
oxygen to dissolve. As a result, freshwater typically contains more dissolved
oxygen than seawater under the same conditions.
4. Gas Composition (Partial Pressure)
The concentration of a gas dissolved in water depends on the partial pressure of that
gas in the surrounding atmosphere. If the partial pressure of oxygen increases, more
