WJEC Biology for AS: Student Bk

Exam practice questions The electron micrograph is of a chloroplast of the thale cress, Arabidopsis thaliana : (c) Name and label on the image of the chloroplast: (i) A part in which photosynthetic pigments such as chlorophyll are at the densest (ii) A store of carbohydrate (iii) The fluid-filled matrix of the chloroplast (3) (d) (i) The actual length of this chloroplast is 5 µm. Calculate the magnification of this diagram and state the number of significant figures to which you have calculated it. (2) (ii) The chloroplast in this electron micrograph is oval but in some preparations, they look almost circular. Explain why it may appear in either of these two ways. (1) (iii) The electron micrograph below shows a section through a chloroplast of the alga Vaucheria . Describe a difference between this chloroplast and a chloroplast of a flowering plant, such as (1) Arabidopsis thaliana . (Total 9 marks) 3 In groups of cells in the pancreas, called islets of Langerhans, are ß-cells, which secrete the hormone insulin into the blood stream. The diagram shows part of one of these cells: (a) Name A and B. (1) (b) Explain the functions of structures E and F. (2) (c) (i) Suggest why this type of cell is likely to contain large numbers of structure C. (2) (ii) Suggest an approximate length for structure C. (1) Fig ST10 F E C B A D  Exam practice questions 125