GCSE Biology Higher Tier: Combined Science Paper 1

Exam Information

This is an AQA GCSE Combined Science: Trilogy Higher Tier Biology Paper from 2019. You've got 1 hour and 15 minutes to complete it, and it's worth 70 marks total.

Make sure you've got a ruler and scientific calculator ready. The paper covers key biology topics that come up regularly in GCSE exams, so it's brilliant practice for understanding how exam questions are structured and what examiners are looking for.

Heart Structure and Function

Your heart is basically a pump with four chambers - two atria at the top and two ventricles at the bottom. The right side pumps deoxygenated blood to your lungs, whilst the left side pumps oxygenated blood around your body.

The pulmonary artery (vessel A in the diagram) carries deoxygenated blood away from the heart to the lungs. This might seem confusing since arteries usually carry oxygenated blood, but remember - arteries always carry blood away from the heart.

Your heart has its own natural pacemaker cells located in the right atrium. These clever cells create electrical impulses that make your heart beat regularly without you having to think about it.

Quick Tip: Remember that the pulmonary artery is the only artery that carries deoxygenated blood - it's a common exam trick question!

Heart Rate Drugs

Some people need medication to slow down their heart rate. Digitalis is one such drug that actually comes from foxgloves - a perfect example of how plants can be used medicinally.

This shows how important it is to protect plant species, as they might contain compounds that could help treat human diseases. Many medicines we use today originally came from natural sources like plants, fungi, or bacteria.

It's quite amazing that something growing in your garden could potentially be used as heart medication!

Did You Know? Many of our modern medicines started as natural compounds found in plants - aspirin originally came from willow bark!

Cardiac Output Calculations

Beta blockers are another type of heart medication. To understand how they work, you need to know this crucial equation: cardiac output = stroke volume × heart rate.

Looking at the data, when someone takes beta blockers at rest, their heart rate drops from 68 to 52 beats per minute, but their cardiac output also decreases from 5440 to 2800 cm³ per minute. Using the equation: stroke volume X = 2800 ÷ 52 = 54 cm³ (to 2 significant figures).

This calculation shows you exactly how beta blockers affect heart function. The heart beats slower and pumps less blood with each beat.

Exam Hack: Always show your working clearly in calculations - you can get marks for the method even if your final answer is wrong!

Beta Blockers and Exercise

Here's why people on beta blockers get breathless during exercise. Looking at Table 1, you can see that beta blockers seriously limit how much your heart rate can increase during exercise.

Without beta blockers, heart rate jumps from 68 to 150 beats per minute during exercise. With beta blockers, it only goes from 52 to 88 - that's a much smaller increase. This means cardiac output is much lower (8624 vs 18000 cm³ per minute).

Since your muscles need more oxygen during exercise, but your heart can't pump blood fast enough to deliver it, you get out of breath. Your body is basically struggling to meet the oxygen demand.

Real Life Connection: This is why people on heart medication often need to take exercise more slowly and build up gradually!

Page Instructions

This page contains no questions - it's just instruction space. In real exams, you might see blank pages like this for extra working space or between different sections.

Always read page instructions carefully during exams to avoid wasting time on pages that don't contain questions.

Digestion Investigation Setup

Amylase is the enzyme that breaks down starch in your digestive system. This experiment uses a clever model to show how digestion and absorption work.

The partially permeable tubing represents your small intestine - specifically the intestinal wall where absorption happens. The water in the test tube represents your bloodstream, where absorbed nutrients end up.

This setup at 37°C mimics your body temperature, making it a realistic model of what happens inside you. The partially permeable tubing only lets small molecules through, just like your intestinal wall.

The experiment tests for both starch (large molecules) and sugar (small molecules) to see what can pass through the tubing.

Memory Trick: Think of the tubing as your gut wall - only small, digested molecules can get through to your blood!

Digestion Results Analysis

Iodine tests for starch (turns blue-black if present), whilst Benedict's reagent tests for sugar (turns orange/red when heated if present).

Initially there's no sugar in test 1 because starch hasn't been broken down yet - the enzyme needs time to work. After 30 minutes (test 3), both starch and sugar are present because amylase has partially digested the starch into sugar.

The key result is test 4 - sugar appears in the water outside the tubing because small sugar molecules can pass through the partially permeable membrane. This perfectly models how nutrients get absorbed into your bloodstream.

Starch never appears outside because those molecules are too large to pass through the membrane.

Exam Success: Always link your explanations back to molecular size when discussing absorption!

Absorption Explanation

Test 4 shows sugar present in the water outside the tubing because sugar molecules are small enough to pass through the partially permeable membrane. This represents absorption - how digested food molecules get from your intestines into your bloodstream.

The starch remains absent from the external water because these molecules are too large to cross the membrane. This is exactly what happens in your body - only fully digested, small molecules can be absorbed.

Key Point: Digestion breaks large molecules into small ones that can be absorbed - it's a two-stage process!