AS & A Level Marine Science (9693) — May–June 2025, Paper 41

6 questions · every question answerable online with instant point-by-point AI marking against the official mark scheme.

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Question 1 · 14 marks · Cell biology / organelles / rough endoplasmic reticulum / electron micrograph

Fig. 1.1 is an electron micrograph of part of a cell from a salmon. The micrograph shows a mitochondrion labelled in the upper right area of the image. A circle is drawn on part…

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Question 2 · 13 marks · Marine organisms / hydrothermal vents / chemosynthesis / Endoriftia / Riftia / tubeworm / mutualism / symbiosis

Endoriftia bacteria fix carbon by chemosynthesis. Endoriftia bacteria live inside giant tubeworms, Riftia. Describe the relationship between Riftia and Endoriftia.

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Question 3 · 18 marks · Marine organisms / oysters / complex life cycle / larvae / dispersal / competition / niches

Oysters are shelled molluscs that have a complex life cycle. The adults are sessile organisms that anchor to a substrate. Fig. 3.1 shows some adult oysters — a photograph of…

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Question 4 · 10 marks · Marine organisms / fish / gills / Spearman rank correlation / statistics / ranking / D²

A student investigated if the surface area of fish gills has a correlation with the activity levels of the fish. The student used a Spearman's rank correlation to test if there…

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Question 5 · 7 marks · Fisheries / Palau / sustainable fishing / fishing restrictions / methods

Fig. 5.1 shows a photograph of Palau, a nation located in the Pacific Ocean. Palau consists of a series of islands surrounded by a range of coral reefs. Reef fish are an important…

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Question 6 · 13 marks · Marine pollution / antifouling paints / heavy metals / bioaccumulation / toxicity / food chains

Fig. 6.1 shows a photograph of a ship's rudder and propeller covered in barnacles. Antifouling paints are often used to prevent barnacle larvae settling on boats. Outline why many…

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