CIE iGCSE Co-Ordinated Science B3.1 Diffusion Exam Style Questions Paper 3
Question
Most-appropriate topic codes (Cambridge IGCSE Coordinated Sciences 0654):
• Topic B7.2 — Digestive system (Part (a)(i), (a)(ii), (a)(iii))
• Topic B4.1 — Biological molecules (Part (b)(i))
• Topic B6.1 — Photosynthesis (Part (b)(ii))
• Topic B3.1 — Diffusion (Part (b)(iii))
▶️ Answer/Explanation
(a)(i) A – stomach; C – large intestine; E – gall bladder
The stomach (A) is a muscular organ that churns food and secretes digestive juices. The large intestine (C) is responsible for absorbing water and forming faeces. The gall bladder (E) stores bile produced by the liver.
(a)(ii) Egestion is the removal of undigested food from the body as faeces
Egestion refers to the elimination of waste material that has not been absorbed during digestion. This is different from excretion, which removes metabolic waste products.
(a)(iii) Insulin
The pancreas (B) produces the hormone insulin, which regulates blood glucose concentration by promoting the uptake of glucose into cells and its conversion to glycogen in the liver.
(b)(i) Test: Heat with Benedict’s solution; Starting colour: Blue; Final colour: Red/orange/yellow/green
Benedict’s solution is a blue reagent that changes colour in the presence of reducing sugars. The final colour depends on the concentration, ranging from green (low) through yellow and orange to red (high concentration).
(b)(ii) Water + carbon dioxide → oxygen + glucose
Photosynthesis uses water and carbon dioxide as raw materials. In the presence of light and chlorophyll, these are converted into glucose (a carbohydrate) and oxygen gas is released as a by-product.
(b)(iii) Ticks in boxes: “Diffusion is the net movement of particles” and “Diffusion is the result of random movement of particles”
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. This occurs because of the random, continuous motion of particles. The other statements describe movement against a concentration gradient (which requires energy) or involve partially permeable membranes (which describes osmosis).
Question
- ………………………………… contraction
- protein …………………………………
- ……………………………….. division
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B3.1 — Diffusion (Part (a))
• Topic B12.1 — Respiration (Part (b))
▶️ Answer/Explanation
(a)(i) Arrow drawn from outside cell to inside cell (left to right)
Oxygen moves by diffusion, from a region of high concentration to a region of low concentration.
Since concentration is higher outside the cell, the net movement is from left to right.
(a)(ii) cell membrane
The line labelled X separates the outside of the cell from the inside.
This structure is the cell membrane, which controls the movement of substances into and out of the cell.
(a)(iii) similarity: both involve random movement of particles down a concentration gradient; difference: osmosis is the movement of water only, across a partially permeable membrane
Both diffusion and osmosis involve particles moving randomly from high to low concentration.
However, osmosis specifically refers to the movement of water molecules across a partially permeable membrane.
(b)(i) carbon dioxide; water
Aerobic respiration is the breakdown of glucose using oxygen.
The word equation is: glucose + oxygen → carbon dioxide + water (+ energy).
(b)(ii) muscle contraction; protein synthesis; cell division
Energy released from respiration is used for many active processes in the body.
These include muscle contraction, building large molecules such as proteins, and cell division for growth and repair.