IB Biology: Hormones & the Endocrine System FAQ

It's assessed through Paper 1 data-based and multiple-choice questions on hormone action, Paper 2 short-answer and extended-response questions linking structure to function, and — for HL students taking Option D (or the Human Physiology HL additional material) — deeper questions on feedback control of blood glucose, thyroxin and the menstrual cycle.

Yes, relatively — not because the content is conceptually difficult, but because it requires linking several systems (nervous, endocrine, reproductive) that students usually revise separately. In fifteen years of marking mocks, the negative feedback loop for blood glucose is where most marks are lost, usually from vague answers that never name the actual hormone.

Core SL content requires insulin, glucagon, thyroxin, leptin, melatonin, FSH, LH, oestrogen and progesterone, plus the general concept of negative feedback. HL students studying the human physiology option add ADH, and a deeper mechanistic understanding of hormone receptor binding (first and second messenger systems).

Start with a feedback-loop diagram for each hormone system, then practise past-paper data questions — that's where marks are actually lost, not in rote recall. I tell every student I teach: draw the loop from memory before you check the textbook, not after.

A typical Paper 2 question gives you a blood glucose concentration graph after a meal and asks you to explain the changes using named hormones. Here's the structure examiners reward: identify the trend, name insulin, state its target (liver, muscle) and its effect (glycogenesis), then explain the return to baseline via negative feedback.

The biggest one: confusing insulin and glucagon direction, or writing "hormones speed up/slow down" without naming which one and why. Another frequent error is mixing up the nervous and endocrine systems' response speed and duration — examiners specifically test this comparison.

No — SL students cover the core hormone content in topic 6.6, while HL students studying the human physiology option go further into ADH, water balance regulation and more detailed receptor mechanisms. HL exam questions also expect more precise biochemical detail in extended responses.

Yes — the menstrual cycle is core content at both SL and HL, including FSH, LH, oestrogen and progesterone interactions across roughly 28 days. Exam questions commonly present a hormone-concentration graph and ask you to identify ovulation, the follicular phase, or explain a specific hormonal interaction.

There's no fixed mark allocation since hormone content is examined across Paper 1 and Paper 2 alongside other topics, but data suggests at least one 6-9 mark extended-response or data-based question touches this content most sessions. It's not a huge chunk of the syllabus by page count, but it appears reliably every year.

Most students find hormones more straightforward than nervous system content (action potentials, synapses), since there's less mathematical reasoning involved — but exam questions often ask students to compare the two systems directly, which trips up students who studied them in isolation.

Usually it's not the hormones themselves but the skill of linking a graph or data set to the correct named mechanism — a command-term issue more than a content gap. If your child can recite hormone functions but freezes on a Paper 2 data question, the fix is targeted past-paper practice, not re-reading notes.

Concise revision notes that summarise each hormone's gland, target and effect in one table, paired with topical past-paper worksheets isolating hormone questions, work better than rereading a full textbook chapter. Mock papers under timed conditions then confirm whether the knowledge transfers under exam pressure.