IBBiologySLPractice Paper QuestionsSet BPractice Paper 1B

Syllabus Edition

First teaching 2023

First exams 2025

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Practice Paper 1B (SL IB Biology)

Practice Paper Questions

1a
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A researcher investigated the effect of pH on the activity of stomach enzyme pepsin. 

Their results are shown in the image below. 

pepsin-rate-of-reaction-at-different-ph-sq

The rate of reaction can be calculated by using the following formula:

reaction space rate space equals space fraction numerator Amount space of space product space produced space left parenthesis straight g space dm to the power of negative 3 end exponent right parenthesis over denominator Time space left parenthesis straight s right parenthesis end fraction

Calculate the rate of reaction at pH 4. Give your answer with the correct units.

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1b2 marks

Describe the differences between the curves at pH 2 and pH 4.

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1c3 marks
(i)

Predict the outcome if the pH were increased to pH 10.

[1]

(ii)

Explain your answer at part i).

[2]

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2a
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The graph below shows the rate of blood flow in various blood vessels in the body. It also shows the total cross-sectional area of the vessels.

YPP-3p1w_screenshot-2023-07-13-at-6-21-47-am

Suggest why the rate of blood flow increases from the venules to the vena cava despite a large decrease in the total cross-sectional area.                                                               

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2b
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The relative thickness of layers in the wall of an artery and a vein are shown in the table below.

Layer in wall Thickness / µm
Artery Vein
Endothelium 25 25
Smooth muscle 495 245
Elastic tissue 375 245
Connective tissue 125 125

 

Explain the difference in the thickness of elastic tissue for the artery versus the vein.

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2c
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The external diameter of a vein was measured at 1.5 mm. 

Calculate the diameter of the lumen of the vein.

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3a
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Typical energy content values of various food group molecules are given in the table below. 

Food Group Typical energy content / kJg-1
Protein 15
Carbohydrate 17
Fat 38


State the molecular feature of fats that allows them to contain more energy per gram than carbohydrates or proteins.

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3b
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The diagram shows a cell with a role in storage.

h-3b

(i)

Identify structures X, Y and Z in this diagram.

[3]

(ii)

Suggest which tissue this cell forms part of.

[1]

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4a4 marks

Scientists investigated the production of high nutrient compost made from organic household waste.

The method they used was as follows:

  1. Place waste in a large container for 125 days
  2. Rotate the container each day
  3. Record the temperature of the waste every 25 days
  4. Remove samples of waste and test nutrient content

The temperature changes that they recorded were as follows:

PGI-YOn5_h-4a

Describe and explain what these data show about the processes occurring in the composter.

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4b3 marks

Nutrient content of the compost was measured at the start and the end of the process.

The results can be seen in the chart below.0cF3o2T9_h-4c

Suggest reasons for the changes in carbon and nitrogen shown in the graph.

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