Eduqas GCSE Biology 2 Transport Systems Exam Questions

About Eduqas GCSE Biology 2 Transport Systems

Transport systems in Eduqas GCSE Biology has three parts: transport in cells, transport systems in humans and transport systems in plants. You start with diffusion, osmosis and active transport across membranes, then see why large organisms with a small surface area to volume ratio need exchange surfaces and transport systems. You then study the double circulation, heart, blood vessels and blood, followed by xylem, phloem, root hairs, leaf structure and transpiration. It links back to cell structure in topic 1 and forward to homeostasis in topic 4. Examiners often set osmosis calculations from the potato practical, heart diagrams with blood flow, and transpiration questions using a potometer.

What you need to know

• 2.1 Diffusion and osmosis Diffusion is the net movement of particles from a high to a low concentration, down a concentration gradient; it is passive. Osmosis is the diffusion of water through a selectively permeable membrane from a dilute solution to a more concentrated solution. Visking tubing can model a cell membrane.
• 2.1 Active transport Active transport moves substances against a concentration gradient and needs energy from respiration, for example mineral ions into root hair cells. SP2.1: the effect of solute concentration on osmosis in potato chips, using percentage change in mass.
• 2.1 Surface area to volume As organisms get bigger their surface area to volume ratio falls, so diffusion across the surface is too slow; they need specialised exchange surfaces and transport systems for oxygen, carbon dioxide, water, food, mineral ions and urea.
• 2.2 The heart and double circulation Blood passes through the heart twice per circuit: right side to the lungs via the pulmonary artery, left side to the body via the aorta. Learn the atria, ventricles, tricuspid, bicuspid and semi-lunar valves, vena cava and pulmonary vein. The left ventricle wall is thicker to pump blood around the whole body.
• 2.2 Blood vessels and blood Arteries have thick muscular and elastic walls for high pressure; veins have thinner walls, a wide lumen and valves; capillaries have walls one cell thick for exchange. Blood contains plasma, red blood cells (haemoglobin, no nucleus, biconcave), white blood cells and platelets. SP2.2: drawing an artery and a vein from a microscope slide.
• 2.3 Xylem and phloem Xylem vessels are dead cells that carry water and mineral ions up the plant. Phloem carries dissolved sugars in both directions, which is translocation. Root hairs take in water by osmosis and mineral ions by active transport.
• 2.3 Leaves and transpiration Learn the cuticle, epidermis, palisade layer, spongy layer, stomata and guard cells. Transpiration is the loss of water vapour from leaves through stomata, which pulls water up the xylem. It increases with light intensity, temperature and air movement, and can be measured with a potometer.

Common mistakes in 2 Transport Systems

• Describing osmosis in terms of solute moving. In osmosis it is water that moves, from a dilute solution to a more concentrated solution through a selectively permeable membrane.
• Saying arteries carry oxygenated blood and veins carry deoxygenated blood as a rule. Arteries carry blood away from the heart; the pulmonary artery carries deoxygenated blood.
• Saying the left ventricle has a thicker wall to pump blood to the lungs. It is thicker because it pumps blood at high pressure around the whole body.
• Writing that phloem transports water. Xylem transports water and mineral ions; phloem transports dissolved sugars.
• Calculating change in mass instead of percentage change in the potato practical. Use percentage change because the chips start at different masses.

Try three 2 Transport Systems exam-style questions