NAS 2 CHALLENGE PRACTICE EXAMS 2025/2026 ANSWERS
AND QUESTIONS GRADED A+
✔✔Name the 3 types of chemical bonds - ✔✔1. Synthesis (Anabolism) - Synthesis
reactions occur when two or more atoms or molecules combine to form a larger, more
complex molecule.
2. Decomposition (Catabolism) - Decomposition reactions occur when a larger molecule
is broken down into smaller molecules, atoms or ions.
1. Exchange Reaction - Exchange reactions involve both synthesis and decomposition
reactions. Bonds are both made and broken. (ATP break phosphate group bond to give
phosphate to glucose - Glucose makes a bond with a phosphate group)
ionic
covalent
hydrogen
✔✔Name four inorganic compounds and describe the common element not found in
these compounds noting the two exceptions - ✔✔water
salt
acids
bases
-does not contain carbon or hydrogen
-does contain hydrogen atoms
✔✔Define the following body fluids; intracellular, extracellular and interstitial - ✔✔-
intracellular fluid (the fluid inside cells)
-extracellular fluid (the fluid outside of the cellular member)
-interstitial fluid (water is the basis)
✔✔Describe the function of water in the body and cells in general - ✔✔-stabilizes
temperature
-water is a solvent
✔✔Define acids, bases, and salts - ✔✔-acid - substance that donates hydrogen ions
and lowers pH
-base - substance that absorbs hydrogen ions and raises pH
-salts - substance when
dissolved in water, dissociates into ions other than H+ or OH-
✔✔Describe what the pH scale measures. - ✔✔-measures the approximate
concentration of hydrogen ions of a substance
-below 7 is acid
-above 7 is basic
, ✔✔Describe how an acid and/or a base is neutralized - ✔✔-use a weak acid to
neutralize bases
-use a weak base to neutralize an acid
✔✔Explain the relationship between a pH number and the concentration of H+ in a
solution. - ✔✔the stronger the acid, the more H+ it donates
✔✔State the pH range of blood that is considered neutral in body chemistry - ✔✔7.35 -
7.45
✔✔Define osmolarity - ✔✔The number of solute particles dissolved in 1kg (g/kg).
OR
The concentration of solutes in a solution.
✔✔Explain how the concentration of solutes affects movement of water between
compartments - ✔✔the higher the osmolarity of a solution the greater osmotic pressure
that solution will have on cells
✔✔Describe how abnormal water movement can affect the size and activity of a cell -
✔✔the ability of a solution to cause a cell to shrink or swell by altering the amount of
water inside the cell
✔✔Describe the relationship between salts in the blood and blood volume - ✔✔this will
increase blood volume, which will increase blood pressure
✔✔Describe how the kidneys regulate blood volume - ✔✔the kidneys can decrease
blood volume by excreting potassium and can increase blood volume by reabsorbing
sodium
✔✔Differentiate between a strong acid and a weak acid - ✔✔-strong acids dissociate
completely
-weak acids partially dissociate (carbonic acid)
✔✔Describe how chemical buffers prevent dramatic changes in H+ concentration of
body fluids - ✔✔one or two molecules that act to prevent dramatic changes in hydrogen
ion concentration when acids or bases are added
✔✔Explain how the kidneys respond chemically when blood pH falls (becomes acidic) -
✔✔- bicarbonate ions are reabsorbed back into the blood capillaries in the kidneys
- hydrogen ions are secreted out of the blood into the kidney tubules
✔✔Explain how the kidneys respond chemically when blood pH rises (becomes
alkaline) - ✔✔- bicarbonate ions are excreted out of the blood and into the urine
AND QUESTIONS GRADED A+
✔✔Name the 3 types of chemical bonds - ✔✔1. Synthesis (Anabolism) - Synthesis
reactions occur when two or more atoms or molecules combine to form a larger, more
complex molecule.
2. Decomposition (Catabolism) - Decomposition reactions occur when a larger molecule
is broken down into smaller molecules, atoms or ions.
1. Exchange Reaction - Exchange reactions involve both synthesis and decomposition
reactions. Bonds are both made and broken. (ATP break phosphate group bond to give
phosphate to glucose - Glucose makes a bond with a phosphate group)
ionic
covalent
hydrogen
✔✔Name four inorganic compounds and describe the common element not found in
these compounds noting the two exceptions - ✔✔water
salt
acids
bases
-does not contain carbon or hydrogen
-does contain hydrogen atoms
✔✔Define the following body fluids; intracellular, extracellular and interstitial - ✔✔-
intracellular fluid (the fluid inside cells)
-extracellular fluid (the fluid outside of the cellular member)
-interstitial fluid (water is the basis)
✔✔Describe the function of water in the body and cells in general - ✔✔-stabilizes
temperature
-water is a solvent
✔✔Define acids, bases, and salts - ✔✔-acid - substance that donates hydrogen ions
and lowers pH
-base - substance that absorbs hydrogen ions and raises pH
-salts - substance when
dissolved in water, dissociates into ions other than H+ or OH-
✔✔Describe what the pH scale measures. - ✔✔-measures the approximate
concentration of hydrogen ions of a substance
-below 7 is acid
-above 7 is basic
, ✔✔Describe how an acid and/or a base is neutralized - ✔✔-use a weak acid to
neutralize bases
-use a weak base to neutralize an acid
✔✔Explain the relationship between a pH number and the concentration of H+ in a
solution. - ✔✔the stronger the acid, the more H+ it donates
✔✔State the pH range of blood that is considered neutral in body chemistry - ✔✔7.35 -
7.45
✔✔Define osmolarity - ✔✔The number of solute particles dissolved in 1kg (g/kg).
OR
The concentration of solutes in a solution.
✔✔Explain how the concentration of solutes affects movement of water between
compartments - ✔✔the higher the osmolarity of a solution the greater osmotic pressure
that solution will have on cells
✔✔Describe how abnormal water movement can affect the size and activity of a cell -
✔✔the ability of a solution to cause a cell to shrink or swell by altering the amount of
water inside the cell
✔✔Describe the relationship between salts in the blood and blood volume - ✔✔this will
increase blood volume, which will increase blood pressure
✔✔Describe how the kidneys regulate blood volume - ✔✔the kidneys can decrease
blood volume by excreting potassium and can increase blood volume by reabsorbing
sodium
✔✔Differentiate between a strong acid and a weak acid - ✔✔-strong acids dissociate
completely
-weak acids partially dissociate (carbonic acid)
✔✔Describe how chemical buffers prevent dramatic changes in H+ concentration of
body fluids - ✔✔one or two molecules that act to prevent dramatic changes in hydrogen
ion concentration when acids or bases are added
✔✔Explain how the kidneys respond chemically when blood pH falls (becomes acidic) -
✔✔- bicarbonate ions are reabsorbed back into the blood capillaries in the kidneys
- hydrogen ions are secreted out of the blood into the kidney tubules
✔✔Explain how the kidneys respond chemically when blood pH rises (becomes
alkaline) - ✔✔- bicarbonate ions are excreted out of the blood and into the urine
