Fig. 1 shows a shell-less hen's egg used by a student to model a cell. The egg was weighed, placed in a beaker of concentrated sugar solution for 40 minutes...
Question 1 Report
Fig. 1 shows a shell-less hen's egg used by a student to model a cell. The egg was weighed, placed in a beaker of concentrated sugar solution for 40 minutes, dried carefully and weighed again. Its mass decreased. The egg membrane allows water molecules to pass through but not the larger sugar molecules.
(a) Draw two arrows on Fig. 1 to show the overall movement of water molecules during the 40 minutes. [2]
(b) Explain why the mass of the egg decreased. [3]
(c) Use the term osmosis to describe how water would move if an identical egg were placed in distilled water. [4]
Answer Details
(a) The arrows must point from inside the egg, across the egg membrane, into the surrounding sugar solution. [2 marks]
(b) The sugar solution is more concentrated and has a lower water concentration than the egg contents. [1 mark] Water molecules move out through the partially permeable membrane. [1 mark] This is the net movement of water down a water-concentration gradient, so the egg loses mass. [1 mark]
(c) In distilled water, water moves into the egg [1 mark] by osmosis. [1 mark] It passes through the partially permeable membrane [1 mark] from the distilled water, with higher water concentration, to the egg contents, with lower water concentration. [1 mark]
Download The App On Google Playstore
Everything you need to excel in your exams
