RP5 Dissection of an animal or plant gas-exchange or mass-transport system Questions

Specification route: RP5
Question bank: 13 questions
Course stage: AS / Year 12

Sample questions

QUESTION 1 · RP5 · LEVEL 1

When performing a dissection of a mammalian heart, what is a key safety precaution identified in the risk assessment?

Always cut away from yourself and your fingers, keeping the non-cutting hand safely out of the path of the scalpel.
Always sterilise the heart in a Bunsen burner flame before cutting.
Dispose of all animal tissue in the standard classroom paper recycling bin.
Ensure the heart is still actively beating before making the first incision.

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Scalpels are extremely sharp surgical instruments.

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Answer: Always cut away from yourself and your fingers, keeping the non-cutting hand safely out of the path of the scalpel.

CPAC 3: Safely uses a range of practical equipment. Cutting away from the body and fingers minimizes the risk of severe cuts if the scalpel slips during dissection.

QUESTION 2 · RP5 · LEVEL 1

When performing a biological drawing of a dissected heart, a student uses shading to show the rounded shape of the ventricles. Why will they lose marks for this?

Scientific drawings must use clear, continuous lines with absolutely no shading, stippling, or sketching.
They should have used cross-hatching instead of smooth shading.
Shading is only permitted when drawing tissues viewed under an electron microscope.
The shading obscures the colour of the cardiac muscle tissue.

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A biological diagram is a structural map, not a piece of art.

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Answer: Scientific drawings must use clear, continuous lines with absolutely no shading, stippling, or sketching.

Apparatus and Techniques (AT e). The strict convention for biological drawings dictates continuous, sharp lines and no shading, as shading can obscure structural details or be misinterpreted.

QUESTION 3 · RP5 · LEVEL 1

During a heart dissection, a student inserts a glass rod into a large blood vessel attached to the heart. The rod passes into the right atrium. Which blood vessel is this?

Vena cava
Aorta
Pulmonary artery
Pulmonary vein

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This vessel brings deoxygenated blood from the body back to the heart.

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Answer: Vena cava

Required practical 5. The vena cava is the major vein that empties deoxygenated blood from systemic circulation directly into the right atrium.

QUESTION 4 · RP5 · LEVEL 1

During the dissection of a mammalian heart, a student needs to distinguish between the left and right ventricles from the outside. What is the most reliable structural feature to look for?

The muscular wall of the left ventricle feels significantly thicker and firmer than the wall of the right ventricle.
The right ventricle is always attached to the aorta.
The left ventricle is a much darker red colour due to containing oxygenated blood.
The right ventricle has large, visible semi-lunar valves on its external surface.

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One side has to pump blood all the way around the body, while the other only pumps to the lungs.

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Answer: The muscular wall of the left ventricle feels significantly thicker and firmer than the wall of the right ventricle.

Required practical 5. The left ventricle has a much thicker muscular wall because it must contract with enough force to generate high hydrostatic pressure for systemic circulation. The right ventricle wall is thinner as it only pumps to the adjacent lungs.

QUESTION 5 · RP5 · LEVEL 2

When making an incision into the heart during dissection, why is it recommended to use a sharp scalpel rather than scissors?

A scalpel creates a clean, single cut that prevents the tearing and distortion of delicate internal structures like the atrioventricular valves and chordae tendineae.
A scalpel is much safer to use than scissors and cannot easily cut the student's skin.
Scissors chemically react with the biological tissue, causing it to rapidly degrade.
A scalpel automatically cauterises the tissue, preventing any residual blood from leaking out.

Show clue

Scissors act with a crushing, pinching motion. A scalpel acts with a slicing motion.

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Answer: A scalpel creates a clean, single cut that prevents the tearing and distortion of delicate internal structures like the atrioventricular valves and chordae tendineae.

Required practical 5 / CPAC 3. Sharp scalpels provide clean incisions that preserve the integrity of underlying structures (like valves and tendons). Scissors can crush or chew the tissue, ruining the anatomical structures intended for observation.

QUESTION 6 · RP5 · LEVEL 2

A student identifies a series of tough, white, string-like structures anchoring the atrioventricular valves to the ventricle wall. What is their biological function?

They are the chordae tendineae (heart strings), and they prevent the valves from turning inside-out (inverting) into the atria during the high pressure of ventricular systole.
They are specialised nerves that carry the electrical impulse directly from the AVN to the apex of the heart.
They are muscle fibres that actively contract to pull the valves open during diastole.
They are coronary arteries supplying the internal muscle with oxygenated blood.

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Think of them as the strings on a parachute, stopping the parachute from blowing inside out in the wind.

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Answer: They are the chordae tendineae (heart strings), and they prevent the valves from turning inside-out (inverting) into the atria during the high pressure of ventricular systole.

Required practical 5. The chordae tendineae are inextensible tendons attached to papillary muscles. When the ventricle contracts, they pull taut, ensuring the AV valves seal shut rather than prolapsing back into the atria.

QUESTION 7 · RP5 · LEVEL 1

In a biological drawing of a dissected organ, what is the strict rule regarding the drawing of label lines?

Label lines must be drawn with a ruler, must not cross over each other, and should not have arrowheads.
Label lines should be drawn freehand to indicate that it is an organic subject.
Label lines must always cross the centre of the diagram to pinpoint structures exactly.
Label lines should be drawn using colored pens to match the colour of the tissue.

Show clue

Scientific diagrams prioritize clarity and neatness above all else.

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Answer: Label lines must be drawn with a ruler, must not cross over each other, and should not have arrowheads.

AT e: Biological drawing conventions. To maintain clarity, label lines must be straight (ruled), end exactly at the structure without an arrowhead, and never cross one another.

QUESTION 8 · RP5 · LEVEL 2

When dissecting a mammalian lung, a student notices rings of hard tissue surrounding the trachea. What is this tissue and what is its purpose?

It is cartilage; it provides structural support to keep the airway open during the negative pressure of inspiration.
It is bone; it protects the fragile lungs from external physical trauma.
It is smooth muscle; it actively contracts to force air down into the bronchi.
It is a highly concentrated ring of alveoli for rapid gas exchange.

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When you breathe in, the pressure drops inside the tube. Without support, a soft tube would collapse like a sucked-in straw.

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Answer: It is cartilage; it provides structural support to keep the airway open during the negative pressure of inspiration.

Required practical 5. The trachea and bronchi are supported by C-shaped rings of cartilage. This prevents them from collapsing under the negative pressure generated when the diaphragm and intercostal muscles expand the thorax.

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