DP Chemistry (last assessment 2024)

Test builder »

Question 19N.3.hl.TZ0.14

Select a Test
Date November 2019 Marks available [Maximum mark: 5] Reference code 19N.3.hl.TZ0.14
Level hl Paper 3 Time zone TZ0
Command term Explain, State Question number 14 Adapted from N/A
14.
[Maximum mark: 5]
19N.3.hl.TZ0.14

Changes in physiology can impact living creatures.

(a)

The graph shows the change in oxygen partial pressure in blood, measured at different pH values.

Explain the effect of changing pH on the percentage saturation of hemoglobin at a given partial pressure of oxygen.

[2]

Markscheme

as pH decreases, protons/CO2 bind to allosteric sites
OR
as pH decreases, protons/CO2 act as non-competitive inhibitor
OR
active/binding site changes shape ✔

saturation decreases
OR
more oxygen released
OR
affinity to oxygen decreases ✔

(b)

Explain the biomagnification of the pesticide DDT.

[2]

Markscheme

accumulates in fat/tissues/living organisms
OR
cannot be metabolized/does not break down «in living organisms»
OR
not excreted / excreted «very» slowly ✔

passes «unchanged» up the food chain
OR
increased concentration as one species feeds on another «up the food chain» ✔

NOTE: Accept “lipids” for “fat”.

(c)

Vitamins are organic compounds essential in small amounts.

State the name of one functional group common to all three vitamins shown in section 35 of the data booklet.

[1]

Markscheme

hydroxyl ✔

NOTE: Accept “hydroxy” but not “hydroxide”.
Accept “alkenyl”.

Do not accept formula.

Syllabus sections