Criterion B in biology is about designing investigations on living material, where variation and ethics matter. A strong design controls what it can and plans repeats for what it cannot.
You say what is being tested and why, using the science behind it.
Your prediction names the variables and is explained with scientific reasoning.
You say how each variable is changed, measured or controlled, and how data will be gathered.
A logical, safe, complete method that someone else could follow and repeat.
A little of the criterion is addressed. Ideas are basic, partly missing, or not linked to the task.
The main points are there but thin. Some explanations are correct; links to the task or evidence are incomplete.
Mostly accurate, well explained and consistently tied to the task, with only small gaps.
Detailed, precise and justified throughout, with ideas connected and applied to new situations or evidence.
A plain-language guide only. Your teacher marks against the official IB level descriptors.
Plan how to investigate the effect of light intensity on the rate of photosynthesis in pondweed.
Put the pondweed near a lamp and count bubbles at different distances.
I will place a 5 cm piece of pondweed in water with sodium hydrogencarbonate and move a lamp to 10, 20, 30, 40 and 50 cm away, using a ruler. I will count the bubbles released in one minute, repeat three times at each distance and calculate the mean. Water temperature is kept constant using a water bath, and the same piece of pondweed is used throughout.
Criterion B is Inquiring and designing. It is marked out of 8 across 4 strands (B.i, B.ii, B.iii, B.iv). Criterion B in biology is about designing investigations on living material, where variation and ethics matter. A strong design controls what it can and plans repeats for what it cannot.
Choose a measurable response, such as bubbles per minute or change in mass, and say how you will count or measure it. Control variables carefully (same plant, light distance, temperature) and say how. Plan repeats and a mean, because living things vary.
A vague dependent variable such as how well the plant does. Ignoring natural variation by testing only one specimen. No mention of how a variable like light intensity is actually changed.
Written by CritABCD for study and revision, in our own words. The official MYP Biology guide and assessment criteria are published by the International Baccalaureate. Official IB guide ↗