48 exam-style questions on Integration of body systems — topic C3.1 of Interaction and interdependence in the IB Biology syllabus — with answers and explanations. Samples below; the full set is free with an account.
Saltatory conduction increases the speed of nerve impulses because the action potential:
Answer: Jumps between nodes of Ranvier
Myelin insulates the axon so ion exchange occurs only at gaps called nodes of Ranvier. The impulse effectively jumps from node to node, greatly increasing conduction velocity.
Which neurotransmitter is released at neuromuscular junctions to stimulate skeletal muscle?
Answer: Acetylcholine
Acetylcholine is released from motor neuron endings at the neuromuscular junction, binding receptors on the muscle fibre and triggering depolarisation and contraction. It is then broken down by acetylcholinesterase.
When blood glucose falls, which hormone stimulates the breakdown of glycogen to glucose in the liver?
Answer: Glucagon
Glucagon, secreted by pancreatic alpha cells, promotes glycogenolysis and gluconeogenesis in the liver, raising blood glucose. Insulin has the opposite effect, lowering blood glucose.
During an immune response, antibodies are secreted by:
Answer: Plasma cells
Activated B lymphocytes proliferate and differentiate into plasma cells, which mass-produce antibodies specific to the antigen. Some become memory cells for faster future responses.
Vaccination produces long-term immunity mainly by stimulating the formation of:
Answer: Memory cells
A vaccine exposes the immune system to antigens, triggering a primary response and the production of memory cells. On later exposure to the real pathogen these enable a rapid, strong secondary response.
In the nephron, most selective reabsorption of glucose and amino acids occurs in the:
Answer: Proximal convoluted tubule
The proximal convoluted tubule reabsorbs nearly all glucose and amino acids, along with much water and salts, using cells rich in mitochondria and microvilli for active transport.
That was 6 of 48 Integration of body systems questions.
Practise all 48 freeDrawAO1 · 1–2 marks
A labelled, accurate drawing with a ruler where lines are straight; axes and units on a graph.
OutlineAO2 · 1–4 marks
A brief account or summary: the main points in two or three sentences, no evaluation.
DescribeAO2 · 1–4 marks
Give a detailed account of what it is or how it happens — steps, features, pattern — without saying why.
48 Integration of body systems questions — free with an account. Spaced repetition, streaks and full exam simulations included.
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