Biology: Water

Question 1

Adhesion

Answer 1

Water molecules ‘stick’ to other charged substances and surfaces.

Question 2

Cohesion

Answer 2

Water molecules ‘stick’ to one another. The negatively charged oxygen atom will have a strong attraction towards the positively charged hydrogen atoms of other water molecules.

Question 3

Capillary action

Answer 3

The mechanism by which water molecules move through the xylem.

Question 4

Capillary action: Adhesion

Answer 4

Water will not fall back down the xylem as they stick to it’s edges (adhesion).

Question 5

Capillary action: Cohesion

Answer 5

As water molecules move through the plant they pull on the other molecules around them, thus pulling all of the water molecules up the xylem, giving the illusion that water is flowing upwards.

Question 6

Solvent

Answer 6

Water is a polar molecule. Other polar molecules such as ionic compounds (e.g., sodium chloride) will dissolve in water. These molecules are hydrophilic. Non polar molecules will not dissolve in water, they are hydrophobic.

Question 7

Polar

Answer 7

A polar molecule has to oppositely charged ends, e.g., water. The oxygen atom is negatively charged and the two hydrogen atoms are positively charged.

Question 8

Lipids

Answer 8

Lipids are non polar and so are insoluble. They combine with proteins to form lipoproteins which can be carried in the blood.

Question 9

Cytoplasm

Answer 9

Polar molecules can dissolve in the watery cytoplasm and react with other substances.

Question 10

Specific heat capacity

Answer 10

The energy (joules) required to raise the temperature of 1 gram of something by 1 degree C. Water has a high specific heat capacity.