Practice Paper 1B (HL IB Biology)

The following apparatus was set up to measure the rate of aerobic respiration by a student. 

Suggest what solution X might be and its function within the experiment.

Describe what ethical concerns the student should consider during this experiment.

The student found the water droplet had moved by 2 cm in 24 hours. The diameter of the lumen of the tube is 1 mm.

The volume of the tubing is given by the equation πr²l ;
Use the value of 3.14 to represent π and note that l refers to the length.

Use the equation to calculate the volume of gas produced in cm³ hour⁻¹, give your answer in standard form.

B lymphocytes are a type of white blood cell. These lymphocytes produce antibodies in response to activation by the presence of an antigen on a pathogen.

The diagram below shows the appearance of a B lymphocyte before and after it has been activated.

Explain the changes that can be observed within the B lymphocyte when it is activated.

Rituximab is a type of antibody that is used to treat certain B lymphocyte cancers (leukaemia). It binds to the cell surface protein CD20 found on B-lymphocytes. Once the antibody binds to the protein it triggers cell death in the cancerous B-lymphocyte. Patients are given rituximab through a drip into a vein on a regular basis for the duration of their cancer treatment.

Based on your knowledge of the immune system, explain why patients would need regular infusions with rituximab.

When treating more aggressive forms of B lymphocyte cancer, rituximab is often combined with more traditional chemotherapies.

The graph below shows the results of a trial looking at the effects of several different treatments, alone and in combination, on B lymphocytes grown in the laboratory.

Rituximab on its own killed 23% of the B lymphocytes while when combined with hydroxyurea it killed 82% of B-lymphocytes in the laboratory.

Calculate the percentage effectiveness of using rituximab in combination with hydroxyurea compared to rituximab on its own. Show your working and give your answer to three significant figures.

A medical doctor concluded that drug combinations are a more effective cancer treatment for human patients than any of the drugs used alone.

Use the information from part c) to evaluate this conclusion.

A horticulturist investigated the inheritance of flower colour in Camellia japonica, a widely cultivated ornamental plant commonly known as Japanese camellia.The horticulturist crossed a homozygous parent with red flowers and a homozygous parent with white flowers. All of the F1 generation had the same colour flowers. Using the following symbols: 

C^R  = Red flowers
C^W = White flowers 

Sketch a genetic diagram / Punnett square to deduce all the genotypes in this cross

Each of the F1 generation plants had flowers that were patterned red and white. The horticulturist undertook a self-cross with these F1 hybrids.

Describe, with a reason, what pattern of inheritance is exhibited in the horticulturist’s experiment.