User interface language: English | Español

Date November 2019 Marks available 3 Reference code 19N.1.SL.TZ0.3
Level Standard Level Paper Paper 1 Time zone Time zone 0
Command term Explain Question number 3 Adapted from N/A

Question

Figure 9(a): Fact file on the round goby (Neogobius melanostomus)

Figure 9(b): Pictures of the round goby and mottled sculpin

Using Figures 9(a) and 9(b), identify one feature of the round goby that shows it is an r-selected species.

[1]
a.

With reference to Figure 9(a), outline how the round goby both positively and negatively affects the St Lawrence River ecosystem.

[3]
b.

With reference to Figure 9(a), explain why the realized niche of the mottled sculpin has changed in recent years.

[3]
c.

Markscheme

frequent egg laying (3 times per year);
many eggs laid at one time (5000);
young fish grow quickly / early maturity.

a.

Positive [2 max]:
provide additional food source for native fish (e.g. yellow perch);
eat other invasive species, such as the zebra mussel.

Negative [2 max]:
increased competition for food, outcompeting native fish;
outcompetes the native mottle sculpin for the best egg-laying sites;
outcompetes native species which may become extinct;
eat other fish eggs, reducing populations/biodiversity;
introduce disease, reducing populations/biodiversity. 

Accept any other reasonable response.
Do not accept only ‘outcompetes native species’, for credit must be linked to competition for food, egg laying sites or species extinction.
Do not accept ‘aggressively takes the habitat of native species’.

b.

resources declined due to competition with round goby;
competition for/loss of nesting sites;
loss of food resources due to additional competition;
realized niche has changed because of impacts of climate change affecting temperature.

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Topic 2: Ecosystems and ecology » 2.1 Species and populations
Show 28 related questions
Topic 7: Climate change and energy production » 7.2 Climate change—causes and impacts
Topic 2: Ecosystems and ecology
Topic 7: Climate change and energy production

View options