Syllabus Edition

First teaching 2014

Last exams 2024

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Practice Paper 2 (DP IB Biology: SL)

Practice Paper Questions

1a
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1 mark

EDTA is a compound that reacts with metal ions to form a stable harmless compound. It is commonly used to reduce levels of calcium in many medical procedures including dental work. EDTA has also been shown to have antimicrobial properties effective in the treatment of Staphylococcus aureus bacteria.

Scientists wanted to establish how effective EDTA could be in the treatment of infections from Escherichia coli bacteria. The growth of E.coli bacteria was monitored in response to treatment with EDTA over a period of 5 days. The chart below shows the results.

q3a_7-1_data_questions_medium_ib_sl_sq

State the reason for the group treated with no EDTA.

1b
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1 mark

Calculate the percentage difference between the number of bacteria in the sample treated with EDTA and the number of bacteria in the untreated sample after 5 days.

1c
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2 marks

Outline the effect of EDTA on the growth of bacteria.

1d
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1 mark

The presence of antibiotic resistance within E.coli populations was studied and presented in the graph below.

q3d_7-1_data_questions_medium_ib_sl_sq

Identify which antibiotic has been shown to be the least effective against E.coli.

1e
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2 marks

Compare the levels of antibiotic resistance shown in E.coli to the antibiotics studied.

1f
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3 marks

The table below shows some of the side effects associated with the antibiotics studied.

Antibiotic

Side effects

EDTA

Abdominal cramps, nausea, vomiting, diarrhoea, headache, low blood pressure, skin problems and fever.

Amoxicillin

Abdominal cramps, back and leg pains, bloating, blood in urine, chest pains

Tetracycline

Nausea, vomiting, diarrhoea, loss of appetite, mouth sores, black hairy tongue, sore throat, headache

Pivmecillinam hydrochloride

Diarrhoea, feeling sick, thrush

Using all the information provided, evaluate whether EDTA is the best candidate antibiotic to treat E.coli.

1g
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1 mark

Suggest a different method that could be used to help reduce the development of antibiotic resistance.

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2a
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1 mark

State the reason why enzymes are referred to as biological catalysts. 

2b
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3 marks
The image below shows a representation of an enzyme-controlled reaction.

enzyme-substrate-complex

Describe the events taking place in the image.

2c
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2 marks

State what is meant by the term 'enzyme specificity'?

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3a
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3 marks

The ends of a DNA strand are referred to as the 3’ end and the 5’ end.

Describe the aspects of DNA structure that give rise to this naming system.

3b
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2 marks

Adenine/thymine and guanine/cytosine form hydrogen-bonds with each other in complementary base-pairing within the DNA double helix. These bases can also form bonds with other molecules in order to carry out their function.

i)

Suggest one other molecule that might form bonds with the bases in a DNA molecule.

[1 mark]

ii)

State the role of the molecule identified in part i).

[1 mark]

3c
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4 marks
The structure of DNA has many characteristics that enable it to carry out its function. 

 

i)

Identify two structural features that help DNA to carry out its function.

[2 marks]

ii)

For each feature identified at part i), explain how it assists with DNA function.

[2 marks]

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4a
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3 marks

Compare and contrast the terms adhesion and cohesion in the context of water molecules in biological tissues. 

4b
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3 marks

The diagram shows a pond skater (or water strider).q4b-2-1-metabolism-water-medium-ib-hl-biology-sq

Certain small animals such as pond skaters and fisher spiders can walk across bodies of water without breaking the surface.

Use your knowledge of water's properties to suggest how detergent pollution contaminating ponds and lakes can have a detrimental effect on these small animals.

4c
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2 marks

Outline how vasodilation affects the volume of water lost as sweat in humans.

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5a
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4 marks

One mark is available for clarity of communication throughout this question.

The drawing below shows an electron micrograph of a neuron. Similar images helped support the Davson and Danielli model of membrane structure.q5a-1-3-cells-membrane-medium-ib-hl-biology-sq

(i)
Describe the Davson and Danielli model of membrane structure.

(ii)
Explain how the structure labeled X was misinterpreted.
5b
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4 marks

 Outline the evidence that led to the Davson and Danielli model being rejected.

5c
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8 marks

Draw an annotated diagram of the cell membrane based on the fluid mosaic model including all the relevant structures.

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