AQA GCSE Combined Science: Trilogy Biology Paper 2 (Higher), 2018: Question 6

📐 Calculations — step by step

1. Read the LH value at day 9: about 17 arbitrary units.
2. Read the LH value at day 12: about 50 arbitrary units.
3. Find the change in concentration: 50 − 17 = 33 arbitrary units.
4. Find the time taken: from day 9 to day 12 = 3 days = 72 hours .
5. Rate = change ÷ time = 33 ÷ 72 = 0.45833...
6. Round to 2 significant figures: 0.46 arbitrary units per hour.

✅ Correct answer

Rate = 0.46 arbitrary units per hour

Mark scheme note: answers of 0.46 or 0.47 score full marks. If the first step is slightly wrong but the final answer is given to 2 significant figures, one mark can still be awarded.

❌ Common errors

• Using days instead of converting to hours.
• Subtracting in the wrong order or reading the graph values inaccurately.
• Forgetting the units: it must be arbitrary units per hour.
• Not rounding to 2 significant figures.

🧠 Exam technique

• Always write the calculation in a clear sequence.
• Use the graph scale carefully — this question rewards accurate reading.
• State units at the end, because a numerical answer alone is not enough for full credit.

💡 Key knowledge

• FSH is produced by the pituitary gland.
• Oestrogen is produced by the ovaries.
• LH is produced by the pituitary gland.
• Progesterone is produced by the corpus luteum / empty follicle in the ovary.

✅ Full-mark answer idea

• At the start of the cycle, FSH from the pituitary stimulates a follicle in the ovary to mature.
• FSH stimulates oestrogen production in the ovaries.
• Oestrogen causes the uterus lining to thicken.
• Oestrogen inhibits FSH but stimulates LH release from the pituitary.
• A high level of LH causes ovulation around day 14.
• After ovulation, the corpus luteum secretes progesterone.
• Progesterone maintains the uterus lining and inhibits FSH and LH.
• If no pregnancy happens, progesterone levels fall and the uterus lining is shed as menstruation.

🧠 How marks are awarded

This is a 5-mark sequencing question. The examiner expects the events in the correct order. You do not need every detail, but you do need a sensible chain of cause and effect. Top answers link each hormone to its source and its effect.

❌ Common errors

• Saying oestrogen is produced by the pituitary — it is produced by the ovaries.
• Saying progesterone causes ovulation — it does not; LH causes ovulation.
• Mixing up the roles of FSH and LH.
• Forgetting that progesterone falls if there is no pregnancy, causing the lining to break down.

✅ Correct answers

• It can mean fewer side effects because the dose may be lower.
• It lasts longer, so you do not have to remember to take a pill every day.
• The hormone goes directly into the bloodstream, so it is not affected by vomiting.

💡 Key knowledge

A patch releases progesterone through the skin. This means it can be easier to use reliably than a tablet, and it avoids problems if the person is sick.

🧠 Exam technique

This is a 1-mark question: one clear advantage is enough. Keep the answer short and direct. No extra explanation is needed unless it helps make the point clearer.

❌ Common errors

• Giving a disadvantage instead of an advantage.
• Saying “it is better” without saying why.
• Talking about unrelated contraceptive methods.

💡 Hormone sources

• FSH — pituitary gland
• LH — pituitary gland
• Oestrogen — ovaries
• Progesterone — corpus luteum in the ovary

💡 Core sequence

• FSH matures follicle
• Oestrogen builds uterus lining
• LH triggers ovulation
• Progesterone maintains lining
• Hormone levels fall if no pregnancy

🧠 Final exam tip

When a question says describe, use a connected chain of events. When it says calculate, show method, use units, and round properly.