Water and pH

Question 1

List some of the reasons that water is fundamental for life.

Answer 1

1. Assists in chemical reactions.
2. Dissolves and transports molecules around the body.
3. Dissipates heat.

Question 2

Name three elements that are very electronegative.

Answer 2

Fluorine, Chlorine and Oxygen.

Question 3

Is water polar or non-polar?

Answer 3

Polar

Question 4

Explain the term hydrophilic in as much detail as possible.

Answer 4

Hydrophilic molecules can dissolve in water (water soluble) and are said to be water loving. A screen forms around these molecules when they react with water allowing the ions to remain in the solution even after dissolving.

Question 5

Explain the term hydrophobic in as much detail as possible.

Answer 5

Hydrophobic molecules do not dissolve in water and are said to be water hating. When put in contact with water, the molecules arrange themselves in a way that limits contact with the surrounding water particles (hydrophobic effect).

Question 6

Explain the term amphipathic in as much detail as possible.

Answer 6

Amphipathic molecules have both hydrophilic and hydrophobic regions. The hydrophobic regions are inside the molecules while the hydrophilic regions are on the outside and this allows these molecules to be water-soluble and dissolve in water.

Question 7

Give examples of hydrophilic molecules.

Answer 7

Alcohols
Sugars
Ketones
Aldehydes
Compounds containing N-H groups.
Charged molecules (ions).

Question 8

Give examples of hydrophobic molecules.

Answer 8

Steroid hormones
Fat soluble vitamins (A, K, D, E).
Lipids
Oxygen.

Question 9

Describe the structure of a micelle.

Answer 9

A micelle is a sphere of phospholipids which has the hydrophobic tails facing inwards and the hydrophilic heads facing outwards. This is a single layer and has no core.

Question 10

Describe the structure of a liposome.

Answer 10

A liposome is a sphere of phospholipids but has a bilayer and a hollow core.

Question 11

Describe the structure of a chylomicron.

Answer 11

Has protein embedded in the shell and lipid stored in the core. There are phospholipid heads are on the outside of the sphere to allow it to be transported in the aqueous plasma of blood.

Question 12

What is the role of a chylomicron?

Answer 12

Transports lipids to the body via the blood.

Question 13

What are buffers used for?

Answer 13

Buffers are used to maintain optimal pH in cells.

Question 14

What can be used as buffers and why?

Answer 14

Weak acids/bases are they only partially dissociate.

Question 15

Where is the phosphate buffer system important?

Answer 15

In the cytoplasm.

Question 16

Where is the bicarbonate buffer system important?

Answer 16

In plasma.

Question 17

Between what pH’s does the phosphate buffer system resist changes?

Answer 17

Approx. 5.9-7.9.

Question 18

What is the equation for the phosphate buffer system?

Answer 18

CO2PO4 -> H+ + HPO4 ^2-

Question 19

Why is the bicarbonate buffer system more complex?

Answer 19

The concentration of H2CO3 is dependant on the concentration of CO2

Question 20

What is the equation for the bicarbonate buffer system?

Answer 20

CO2 + H2O -> H+ + HCO3^-

Question 21

The bicarbonate buffer system is affected by which two organ systems?

Answer 21

Lung and kidney.

Question 22

How is the bicarbonate system affected by the lungs?

Answer 22

Increase or decrease in ventilation will change CO2 levels.

Question 23

How is the bicarbonate system affected by the kidneys?

Answer 23

Changes in bicarbonate reabsorption or secretion change overall plasma bicarbonate.

Question 24

What would happen without the bicarbonate buffer system?

Answer 24

The blood pH would fluctuate wildly as, for example, cellular products of acids (e.g. lactic acid) would cause marked drops in blood pH.

Question 25

What can the Henderson-Hasselbalch equation be used to calculate?

Answer 25

How the pH of a physiological solution will respond to changes

Question 26

Why are amphipathic molecules able to dissolve in water?

Answer 26

Have both a hydrophobic and hydrophilic region and ensures the hydrophobic region is on the inside and the hydrophilic region is on the outside.

Question 27

Discuss the swap which can lead to sickle cell anaemia.

Answer 27

Hydrophilic glutamic acid is replaced w hydrophobic valine.

Question 28

Discuss the effect of switching hydrophilic glutamic acid to hydrophobic valine.

Answer 28

Hydrophobic regions form on the surface which attracts other molecules of haemoglobin.
This causes clumping of haemoglobin molecules forming rigid fibres.
This can lead to sickling and therefore sickle cell anaemia.

Question 29

Why is the hydrophilic outer shell of chylomicron essential?

Answer 29

Allows the chylomicron to be transported in the aqueous plasma of the blood.

Question 30

What happens if water dissociates?

Answer 30

It splits into a hydrogen ion and a hydroxide ion.

Question 31

What happens to strong acids or bases?

Answer 31

They fully dissociate.

Question 32

Give an example of a strong acid.

Answer 32

HCl
Hydrochloric acid

Question 33

Give an example of a strong base.

Answer 33

NaOH
Sodium hydroxide

Question 34

What occur if the H+ conc. is too high?

Answer 34

Acidosis

Question 35

What occurs if the H+ conc. is too low?

Answer 35

Alkalosis

Question 36

What does a decrease in CO2 lead to?

Answer 36

Respiratory alkalosis.