Is IB Biology hard?

HL is a big step up from SL. At either level the hard part is applying what you know to unfamiliar data and examples.

Syllabus content	110 hours at SL, 180 at HL
Exams	3 hours at SL, 4.5 hours at HL
HL-only topics	Six, from origins of cells to gene expression
Internal assessment	20%, the same at both levels

What makes it hard

Paper 1B and Paper 2 are built on unfamiliar data: tables, graphs and trends.
The volume of content, especially at HL.
Extended responses that need precise terms in a logical order.

Try 2 questions

Question 1

The graph shows the rate of uptake of two substances, A and B, by cells at different external concentrations. Neither uptake changes when a respiratory inhibitor is added. Which explains why curve B levels off?

Question 2

Mean contractile vacuole emptying rate at five external sodium chloride concentrations: 0 mmol dm⁻³, 12 per min; 25, 9 per min; 50, 6 per min; 75, 4 per min; 100, 2 per min.
External NaCl concentration / mmol dm⁻³	Mean emptying rate / min⁻¹
0	12
25	9
50	6
75	4
100	2

Paramecium is a single-celled freshwater organism with no cell wall. Its contractile vacuole collects water and expels it from the cell. The table shows how often the vacuole emptied in salt solutions of different concentrations. Which explanation of the data is best supported?

Next step

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Questions people ask

Is IB Biology HL harder than SL?

Yes: 180 hours of content against 110, six extra topics, more depth in many others and 4.5 hours of exams against 3.

Which theme grows most at HL?

Continuity and change: 60 hours at HL against 34 at SL.