Practice Paper 1B (SL IB Biology)

As part of an investigation cubes of potato were placed in a solution containing sodium ions. The concentration of oxygen in air bubbled through the solution was changed and the rates of respiration and uptake of sodium ions were measured. The results are shown in the table below.

Describe the relationship between oxygen concentration, rate of respiration and rate of uptake of sodium ions.

Suggest reasons for the relationship between oxygen concentration, rate of respiration and rate of uptake of sodium ions described in part (a).

Give two similarities between the processes by which inorganic ions and water molecules enter cells.

Distinguish between the passive and active movement of molecules across cell membranes.

Scientists investigated the presence of bacteria resistant to the antibiotic tetracycline in poultry and in the farmers who kept them. They looked for Escherichia coli (E.coli) resistant to tetracycline. The scientists took samples of faeces from the poultry birds and the farmers. Turkey farmers often used food containing tetracycline, whereas chicken farmers did not very often.

The bacteria were grown on nutrient agar containing tetracycline. Resistant bacteria grew and were visible as colonies on the agar plates.

The results are shown in the table below.

 Suggest a hypothesis the farmers were testing in this investigation.

Describe the results of the scientists’ investigation described in part (a).

Scientists investigated treatment of a human respiratory infection caused by a species of bacterium. This species of bacterium is often resistant to the antibiotics currently used for treatment. They investigated the use of a new antibiotic to treat the respiratory infection. The new antibiotic blocks DNA replication in bacterial cells.

The scientists tested the new antibiotic on mice with the same respiratory infection.  The antibiotics were given to the mice at a dose of 25 mg kg⁻¹ per day.

Calculate how much antibiotic would be given to a 33 g mouse each day.

A group of insects called flower thrips includes the species Frankliniella intonsa, as shown in the image below.

Adult F. intonsa flower thrips pollinate flowers of the genus Stellera in central and southern Asia. In return for the pollination it receives, Stellera provides sites for F. intonsa to lay their larvae (young).

State how this differs from a more conventional insect-flower mutualistic relationship. 

Changes to abiotic conditions such as those caused by climate change can disrupt mutualism between pollinators and flowering plants. 

Suggest the consequences of extinction of a pollinator on other species. 

A symbiotic relationship between two species is defined as any type of a close and long-term biological interaction between two different biological organisms.

The relationship between a bumblebee and the flowers it feeds from (and pollinates) is referred to as mutualistic.

Using this information, distinguish between symbiosis and mutualism.

The best-documented examples of animal pollinators include bees and other insects. However, some larger animals are very active pollinators. 

One such animal is the honey possum (Tarsipes rostratus), a small marsupial native to southwestern Australia. Some of the pollen that a honey possum comes into contact with is used as a food, with all the available nutrients being used by the honey possum for its own dietary requirements.

Suggest one adaptation, from the image above, of the honey possum that hints at its role as a pollinator.