Question

The Fitness of Water. For each of these statements about water, decide whether the statement is true and describes a property that makes water a desirable component of cells (T); is true but describes a property that has no bearing on water as a cellular constituent (X); or is false (F). For each true statement, indicate a possible benefit to living organisms.

a. Water is a polar molecule and hence an excellent solvent for polar compounds.
b. Water can be formed by the reduction of molecular oxygen O2.
c. The density of water is less thaan the density of ice.
d. The molecules of liquid water are extensively hydrogen-bonded to one another.
e. Water is odorless and tasteless.
f. Water has a high specific heat.
g. Water has a high heat of vaporization.

Answer 1

Water's properties as a polar molecule with extensive hydrogen bonding confer critical biological advantages like excellent solvent capability, temperature regulation, and insulation for aquatic ecosystems. However, the fact that water is odorless and tasteless does not affect its biological role. One statement regarding the formation of water by oxygen reduction is false.

Step-by-step explanation:

Let's evaluate each statement about water with respect to its properties and relevance to the biological functions of cells:

1. Water is a polar molecule and hence an excellent solvent for polar compounds (T): This allows cells to dissolve and interact with various substances required for life's processes, such as nutrients, gases, and waste products.
2. Water can be formed by the reduction of molecular oxygen O2 (F): Water is typically formed by the combination of hydrogen and oxygen during cellular respiration or photosynthesis, not by the reduction of oxygen alone.
3. The density of water is less than the density of ice (T): This unique property ensures that ice floats on water, providing insulation for aquatic ecosystems and affecting the climate.
4. The molecules of liquid water are extensively hydrogen-bonded to one another (T): This property gives water a high specific heat and surface tension, important for temperature regulation and movement of water through organisms.
5. Water is odorless and tasteless (X): While true, this property does not impact water's role as a cellular constituent.
6. Water has a high specific heat (T): This helps to stabilize internal temperatures of organisms and environments, allowing for homeostasis.
7. Water has a high heat of vaporization (T): This enables cooling mechanisms such as sweating and transpiration, preventing overheating in organisms and plants.

Answer 2

A) True

The polarity of water is what makes it an ideal transport vehicle for nutrients and micronutrients that are water-soluble. Within organisms, water can be used to transport nutrients and even waste from one part of the body to the other. In the case of humans, urine is used to get rid of soluble waste from within the body.

B) True

During the process of photosynthesis, carbon dioxide (CO2) and water (H2O) are taken from the air and soil respectively. Oxygen is able to produce water when it is reduced. Hydrogen during this process is oxidized.

C) False

Ice floats on water. Hence it cannot be denser than water. Rather, water is denser than Ice. Because of the structure of hydrogen bonds, when they are iced, the bonds tend to pull apart, thus making ice expand somewhat. This expansion creates microscopic pockets of air in the molecules thus given them buoyancy.

D) True (X)

E) True (X)

F) True

Heat Capacity refers to the amount of heat a substance like water can absorb before it's temperature rises by 1 degree. This property is important, because, were it not for the high specific heat capacity of water, many people and plants would have boiled over.

G True (X)

Heat of vaporization is the kind and amount of energy required to alter one gram of liquid into a gas at boiling point

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