5 (a) Complete the table by giving one function of each organelle. 8 Areas outside the box will not be scanned for marking Organelle Function Mitochondrion Rough endoplasmic Smooth endoplasmic Golgi body (4 marks) (08) APW/Jan09/BYB1
9 Areas outside the box will not be scanned for marking Photographs A and B show epithelial cells from the small intestine. One photograph was taken with a light microscope and the other with an electron microscope. Both photographs were taken at a similar magnification. A B Nucleus 5 (b) Which photograph was taken with an electron microscope? Explain your answer. Photograph... Explanation... 5 (c) The nucleus labelled in photograph B is 10 µm in length. What is the magnification? Answer... times (1 mark) 7 Turn over (09) APW/Jan09/BYB1
Biology B - AQA GCE Mark Scheme 2009 January series Question Part Sub Part Marking Guidance Mark Comments 5 (a) Organelle Function mitochondrion rough endoplasmic smooth endoplasmic Golgi body (Aerobic) respiration / produces ATP; Protein synthesis; Transport of (proteins / lipids / steroids) / production of lipids; Modifying / packaging (proteins); 4 1 mark for each correct function Reject produces / makes energy 5 (b) Better resolution; Microvilli visible (in B); B, no mark Reject higher magnification If A no marks Membrane-bound organelles visible (in B); Example of; 2 max 5 (c) 2100; 1 7
10 LEAVE MARGIN BLANK 5 The drawing shows a section through part of an alveolus from a human lung. The drawing has been made from an electron micrograph. The magnification of this drawing is 3600 times. Epithelium of alveolus Lumen of alveolus Red blood cells Capillary endothelium X (a) (i) Explain why the red blood cells in the drawing are different in shape. APW/Jun07/BYA1
Biology Specification A - AQA GCE Mark Scheme 2007 June series Question 3 (a) (i) Box enclosing H from one OH group and OH from the other; 1 (ii) C 12 ; H 22 O 11 ; 2 (b) (c) Heat/warm with Benedictís solution; Turns green/yellow/orange/red; 2 Do not credit use of a water bath unless some indication of temperature provided. Different number of glucose (units); (Different proportions of) amylose/amylopectin; Different number of branches in molecule/ branches in different places 1 Total 6 Question 4 (a) Active site not totally complementary/does not match exactly; Wraps round substrate/ Enzyme changes shape; 2 (b) (i) Substrate used up/decreases (as time passes); 1 (ii) Heating provides more (kinetic) energy; Molecules move faster; More collisions/es complexes formed; 3 (c) Denaturing of enzyme; Accept clear description 1 Question 5 Total 7 (a) (i) They are sections/ cut; Through different planes/parts of cell/ viewed from a different angle; Cells also distorted by passage through capillaries; 2 max (ii) One mark for correct answer of 0.8 ñ 1.4 µm One mark for dividing measured length by magnification; 2 Be reasonable about accepting value for minimum diffusion distance. Answers just outside this range should be accepted providing evidence of method used is sufficiently clear. (b) (i) (Lining of) alveoli moist/surface film of fluid/water; Evaporates; Due to warm body temperature; 2 max (ii) More carbon dioxide and less oxygen; 1 Reference to nitrogen must refer to concentration Total 7 4
10 LEAVE MARGIN BLANK 5 (a) The table shows some of the features present in three different cells. Complete the table with a tick if the feature is present or a cross if it is absent. Plasma membrane Feature Leaf cell Red blood cell Bacterial cell Mitochondrion Chromosomes containing both DNA and protein (3 marks) (b) It is not possible to see the detailed structure of a mitochondrion with an optical microscope. Explain why. (c) Some mitochondria are branched. The diagram shows the shape of a branched mitochondrion. A transmission electron microscope may not show that this mitochondrion is branched. Use this diagram to explain why. APW/Jan07/BYA1 7
BYA1 - AQA GCE Mark Scheme 2007 January series Question 5 (a) Plasma membrane Feature Leaf Cell Red Blood Cell Bacterial Cell!!! Mitochondrion! # # Chromosomes containing both DNA and protein!; #; #; One mark for each correct column 3 Do not accept marks as bring equivalent to crosses (b) (c) Light microscope has low resolution; Light has long wavelengths; Accept converse providing candidate is referring to optical microscope 2 Specimen thin / plane / section; Ignore ìplane of focusî May not go through branch / only go "across" mitochondrion; 2 Total 7 Question 6 (a) Lowers activation energy (of reaction); More molecules able to react; By splitting the reaction into stages; Allows E-S complex to be formed; Provide a surface/place for reaction; 2 max (b) (i) Sand + (boiled potato) + hydrogen peroxide/substrate; To show that the enzyme produced the reaction / sand had no effect / see if sand has an effect; 2 (ii) High temperature denatures / temperature affects rate of reaction / volume of gas affected by heat / only one variable; 1 Total 5 5