You are viewing a free preview of this lesson.
Subscribe to unlock all 10 lessons in this course and every other course on LearningBro.
The 6-mark extended-response questions are the highest-tariff items on both Paper 1 and Paper 2, and they are marked differently from every other question. Instead of a point-by-point mark scheme, the examiner uses a levels-of-response mark scheme: your whole answer is read and placed in a level (Level 1, 2 or 3) based on how much correct, relevant, well-organised science it contains. This means the structure, coherence and scientific language of your answer matter just as much as the facts. A jumbled answer with correct points can score below a well-organised answer with the same content.
By the end of this lesson you should understand how the level descriptors work, be able to plan and sequence a 6-mark answer, know how to cover both sides of an "evaluate" question, and be able to lift a response from the middle band to the top band.
Examiners use a three-level mark scheme. The exact wording varies by question, but the shape is always like this:
| Level | Marks | What it rewards |
|---|---|---|
| Level 3 | 5–6 | A detailed, coherent answer showing thorough understanding. Correct terminology throughout. Logically structured, with ideas clearly linked. For "evaluate", a supported conclusion. |
| Level 2 | 3–4 | Reasonable understanding. Some correct terminology. Some structure, but links may be incomplete or the answer one-sided. |
| Level 1 | 1–2 | Limited understanding. Simple, mostly isolated statements with little linking. Terminology absent or misused. |
| 0 | 0 | No relevant content. |
The key insight: moving up a level is not just about adding more facts — it is about linking them into a logical chain and using the right vocabulary. Three connected, well-expressed points beat six disconnected ones.
Exam Tip: Level descriptors reward coherence and linkage, not a longer list. Before you write, decide the order your points should go in so each one leads to the next.
A planned answer almost always outscores an unplanned one. Spend the first 60–90 seconds planning:
A sensible time budget for a 6-marker is about 7 minutes: ~30 s to read and underline, ~90 s to plan, ~4.5 min to write, ~30 s to check.
Exam Tip: For an evaluate 6-marker, plan two columns — for and against — and a one-line conclusion before you write a word. That guarantees you cover both sides and finish with the judgement the top level demands.
Take: "Explain how the body responds to a rise in blood glucose concentration and returns it to normal. (6 marks)."
A margin plan might read:
Six linked points, in order, each leading to the next — that is a Level 3 skeleton before any prose is written.
Question (6 marks): A leaf in bright sunlight is photosynthesising rapidly. Explain how the structure of a leaf is adapted for efficient photosynthesis, and explain why increasing the light intensity eventually stops increasing the rate.
This is a synoptic question: it links leaf structure (B3/B1) with limiting factors (B1). The three responses below show the same question answered at three levels.
Mid-band response: "Leaves are thin and flat so light can get in and gases can move easily. They have lots of chloroplasts which contain chlorophyll to absorb light for photosynthesis. There are stomata to let carbon dioxide in. If you increase the light the rate goes up, but after a while it stops going up because something else runs out, like carbon dioxide."
Examiner-style commentary: A sound Level 2 answer. It names several correct adaptations and grasps that the rate plateaus when another factor becomes limiting. To climb to Level 3 it needs to link each structure to its function precisely (palisade layer at the top for maximum light absorption; spongy layer with air spaces for diffusion), name the limiting factor explicitly, and explain why extra light then has no effect.
Stronger response: "A leaf is thin and flat, giving a large surface area and a short diffusion distance for gases. The palisade mesophyll near the upper surface is packed with chloroplasts containing chlorophyll, which absorbs light energy. The spongy mesophyll has air spaces so carbon dioxide can diffuse to the cells, and stomata on the lower surface let CO₂ in and oxygen out. Increasing light intensity increases the rate of photosynthesis because more light energy is available. Eventually the rate levels off because another factor, such as carbon dioxide concentration or temperature, becomes limiting — so providing more light cannot increase the rate any further."
Examiner-style commentary: A strong Level 3 answer: structures are linked to functions, the limiting-factor idea is named and explained, and terminology is accurate throughout. To make it watertight at the top of Level 3 it could add why a limiting factor caps the rate (the reaction can only proceed as fast as its slowest-supplied requirement allows) and reference the role of temperature affecting the enzymes controlling the reaction.
Top-band response: "A leaf is adapted to maximise the rate of photosynthesis. It is thin and flat, giving a large surface area to capture light and a short diffusion pathway for gases. Just beneath the transparent upper epidermis, the palisade mesophyll cells are tightly packed and rich in chloroplasts, positioning the light-absorbing chlorophyll where the light is brightest. Below this, the spongy mesophyll contains large air spaces that allow carbon dioxide to diffuse rapidly to the photosynthesising cells, while stomata (opened by guard cells) on the lower surface admit CO₂ and release O₂. A network of xylem delivers water and phloem removes the glucose produced. As light intensity rises, the rate of photosynthesis increases because light provides the energy for the light-dependent stage. However, the rate eventually plateaus because a different factor becomes limiting — typically carbon dioxide concentration or temperature. The overall rate can only be as fast as its slowest-supplied requirement allows, so once CO₂ (or the activity of the enzymes controlling the reaction, which depends on temperature) limits the process, additional light has no further effect."
Examiner-style commentary: Full marks. Every structure is tied to a clear function, the answer flows logically from light capture to gas exchange to transport, and the limiting-factor explanation gives the underlying reason — not just that the rate plateaus but why. The synoptic links (xylem/phloem, enzymes and temperature) and precise terminology are exactly what lifts an answer to the top of Level 3.
Not every 6-marker is built the same way. The command word tells you which shape the top-band answer should take, and choosing the wrong shape is a common reason able students stall at Level 2.
| Command word | Structure of a Level 3 answer |
|---|---|
| Describe (a process) | An ordered sequence of steps, each following logically from the last |
| Explain | A linked chain of reasoning — each what paired with its why using "because"/"so" |
| Compare | Point-by-point similarities and differences, linking the two things in each point |
| Evaluate / Discuss | Points for, points against, then a supported conclusion |
Subscribe to continue reading
Get full access to this lesson and all 10 lessons in this course.