DP Biology (last assessment 2024)

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Question 23M.3.HL.TZ1.6

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Date May 2023 Marks available [Maximum mark: 7] Reference code 23M.3.HL.TZ1.6
Level HL Paper 3 Time zone TZ1
Command term Describe, Outline, State Question number 6 Adapted from N/A
6.
[Maximum mark: 7]
23M.3.HL.TZ1.6

Dopamine transporter protein (DAT) is involved in the reabsorption of dopamine in presynaptic neurons. Mice can be homozygous (+ / +) or heterozygous (+ / –), or they can lack the gene (– / –) to produce DAT. Mice were given four injections of the stimulant methamphetamine, each given two hours apart, and the level of dopamine in synapses in the brain was recorded after two days. The data is presented as percentages of dopamine levels in saline controls.

[Source: Copyright 1998 Society for Neuroscience.]

(a)

Using the data in the graph, state the effect of DAT on dopamine concentration in synapses.

[1]

Markscheme

decreases (concentration of dopamine)

Examiners report

Most could correctly interpret the graph for one mark.

(b)

Describe the effect of stimulants on the nervous system.

[3]

Markscheme
  1. increase psychomotor arousal/alertness;
  2. increase transmission at synapses in the brain;
  3. they increase the concentration of dopamine/neurotransmitter;
  4. dopamine is involved in the brain’s reward pathway
    OR
    stimulate pleasure areas of the brain;
  5. block re-uptake of dopamine/ block uptake transporters;
  6. high concentration of dopamine/neurotransmitter remains in the synapse so continues pleasure;
Examiners report

Descriptions of the effect of stimulants on the nervous system were very poor. The only mark that seemed to be awarded was for an increase in dopamine.

(c)

Sedatives are a group of drugs that relax the central nervous system. State one example of a sedative drug.

[1]

Markscheme

benzodiazepines
OR
alcohol
OR
tetrahydrocannabinol/THC;

 

Accept other valid example, no commercial names valid.

Examiners report

Many correctly named a sedative drug although some incorrectly gave 'marijuana' rather than THC or indicated an anaesthetic.

(d)

Outline how social environment can contribute to drug addiction.

[2]

Markscheme
  1. friends taking drugs may influence taking drugs for a feeling of belonging/peer pressure;
  2. certain cultures/locations have a greater incidence of drug use (so it may seem normal);
  3. low income increases the likelihood of addiction for escapism;
  4. poor knowledge of drug addiction/abuse;
  5. personal problems/illness/mental health issues /stress/emotional issues for escapism;