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Transport · Paper 2 — Free Biology HL Practice Questions

What this topic covers

This theme is built on one repeated argument: structure exists because it does a job, and you can predict the job from the structure. Examiners test this exact logic at every scale — a motor protein's shape tells you which way it walks a microtubule, a red blood cell's missing nucleus tells you why it can pack more haemoglobin, a gill's countercurrent geometry tells you why it out-performs a lung-style parallel flow. Several chunks here — muscle and motility, enzyme kinetics, endosymbiotic theory, detailed phloem loading — exist only on the HL paper, and they're flagged below. Get the mechanism words right (troponin, not tropomyosin; ATP-binding, not hydrolysis) because that's where the marks actually sit.

Read the full Form and Function lesson notes →

1MasterySAQ-SBlood circulation in mammals (cardiovascular system)6 marksPaper 2~9 min

During a medical examination, a doctor uses a stethoscope to listen to the heart sounds of a healthy adult. The characteristic 'lub-dub' sound is heard.

(a)

State what causes the first heart sound ('lub') and the second heart sound ('dub'). [1 mark]

(b)

Describe the function of chordae tendineae and papillary muscles during ventricular contraction. [2 marks]

(c)

A runner has a stroke volume of

85\,\text{cm}^3

and a heart rate of

150\,\text{beats per minute}

immediately after a sprint. Determine the cardiac output in

\text{dm}^3\,\text{min}^{-1}

. [1 mark]

(d)

Explain why heart rate increases during exercise, referring to the role of

\text{CO}_2

concentration in the blood. [2 marks]

Solutions

2MasterySAQ-SBlood circulation in mammals (cardiovascular system)5 marksPaper 2~8 min

A scientist investigates the structure of mammalian arteries and veins using a light microscope. She observes that the wall of an artery is much thicker and more muscular than the wall of a vein of similar diameter.

(a)

State how the thick, muscular wall of an artery relates to its function. [1 mark]

(b)

State the role of valves in veins. [1 mark]

(c)

Calculate the mean arterial pressure (MAP) for a patient with blood pressure

145/95\,\text{mmHg}

, using the formula:

\text{MAP} = P_{\text{diastolic}} + \frac{1}{3}(P_{\text{systolic}} - P_{\text{diastolic}})

[1 mark]

(d)

A patient is diagnosed with venous valve incompetence (leaky valves) in the legs. Explain the physiological consequences of this condition for venous return and tissue fluid balance. [2 marks]

Solutions

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