Practice Paper 2 (SL IB Biology)

The image below shows a mangrove forest, an example of a tropical, coastal habitat.

Katja Schulz, CC BY 2.0, via Wikimedia Commons

Identify three abiotic factors acting on mangrove trees in this habitat.

Identify one adaptation of mangrove trees that is visible in the image.

[1]

(ii)

Explain how this adaptation aids survival.

[2]

The map below shows the global distribution of mangrove habitat.

Describe mangrove forest distribution.

[1]

(ii)

Suggest an explanation for the distribution shown in the map.

[2]

Farmers can plant their crops at different times throughout the year. Traditionally crops were planted in April and harvested in September. However, in modern times farmers have switched to planting their crops in September and harvesting in June/July.

Scientists decided to investigate the effect that the change in planting time had on the number of species of farmland birds over 10 years. The scientists counted the number of farmland birds found within a 1km radius of farm X that plants its crops in April, and within a 1km radius of farm Y that plants its crops in September.

The graph below shows the data they collected.

Describe the results seen in the graph. 

Using the graph in part (a), calculate the difference between the percentage change in bird species number across the two farms from 1992 to 2000. 

Explain the type of biodiversity that is being measured in this experiment.

[2]

The agricultural area is found to have a very low ecosystem diversity.

List three changes that could be made to improve ecosystem diversity in the area. 

[3]

Spirulina (Athrospira platensis) is a blue-green alga that is consumed for its nutritional benefits, which are considered to be good for oral health, eye health and maintaining healthy blood pressure, amongst other benefits.

The graph shows the results from an investigation into the optimum growing conditions for Spirulina. 

Spirulina was grown in a glucose medium and exposed to different intensities of light. The same method was carried out with an autotrophic species of alga.

Explain how the results show that Spirulina is a mixotrophic organism.

Compare the growth rate of Spirulina and the autotrophic algal species when light intensity was increased from 0 to 200 lx.

Suggest how Spirulina may be adapted to function as a mixotroph.

Elodea canadensis (Canadian pondweed) is a species of aquatic plant from North America. A student grew Elodea canadensis, along with a pondweed species native to the UK, in water tanks both separately and together. The graphs below show their results.

State two abiotic factors the student should have controlled throughout the experiment. 

Calculate the difference in biomass between native pondweed grown separately and native pondweed grown in a tank together with E. canadensis after 15 days. 

Explain the results for native pondweed for when both species of pondweed are grown together.

The images show two organisms from the genus Canis.

Grey wolves, Canis lupus, are wild animals native to Eurasia and North America.

Domestic dogs, Canis familiaris, descended from wolves and became domesticated over many years.

A wolfdog is a hybrid produced when a domesticated dog (Canis familiaris) breeds with a wolf (Canis lupus). Genetically, dogs and wolves are very similar and the resulting offspring are fertile. Wolfdog hybrids are rare as natural habitats and territorial behaviours isolate wolves from domestic dogs.

Using the information provided, discuss the validity of the claim that wolves and dogs are the same species.

A taxonomist suggested that the wolf and the domestic dog should be re-categorised as follows:

• Canis lupus familiaris
• Canis lupus lupus

Identify the genus name and the species name for the wolf and the domestic dog under this re-categorisation.