2014 GCE O Level Bio Suggested Answer JEN

2014 GCE O Level Biology Suggested Answer Paper 1 1 2 3 4 5 6 7 8 9 10 A B C C D B B B B C 11 12 13 14 15 16 17 18 19 20 D C D C D C A C A C 21 22 23 24 25 26 27 28 29 30 C C C D C D B A C A 31 32 33 34 35 36 37 38 39 40 C D C C B A A C A B Paper 2 (Section A) 1 (a) Excretion is the process by which metabolic waste products and toxic substances are removed from the body of an organism [1]. It helps to prevent metabolic waste products from accumulating in the body, which can be toxic and can cause death [1]. (b) (i) 183 [1] (ii) Carbon dioxide / bile pigments / creatinine / uric acid [1] (c) When LESS ADH is secreted, it decreases the permeability of cells at the collecting ducts to water [1]. LESS water is then reabsorbed from the collecting duct into the blood capillaries [1]. This results in a larger volume of urine to be excreted that is also less concentrated [1]. 2 (a) Liver [1] (b) (i) Total volume of drinks = 3 x 175 = 525 cm3 Total alcohol consumed = (12 / 100) x 525 = 63 cm3 Number of units of alcohol consumed = 63 / 10 = 6.3 units (ii) 6.3 hours Questions to note: 6, 7, 14, 23, 31, 39 Question to note: 1a, 3, 5a, 5b, 6bii, 8bii, 9, 10, 11O

(c) Short term: 1. Slower reaction time [1] 2. Headache / reckless behaviour [1] Long term: 1. Liver cirrhosis [1] 2. Stomach cancer / addiction to alcohol [1] 3 (a) (i) vein (ii) Xylem [1]; has an empty lumen without any protoplasm to reduce resistance of water flowing through the xylem [1]. Xylem [1]; Walls are thickened with lignin to provide structural support for the plant and to prevent the vessel from collapsing [1]. (b) (i) Transpiration [1] (ii) 8.8 hours [1] (17-8.2) (iii) 6 and 20 hours [1] (iv) Humidity / light intensity [1] 4 (a) It is an area that stores carbon compounds for an indefinite period [1] . It stores more carbon than it releases. [1] (b) (i) Cellular respiration [1] (ii) It helps to reduce the amount of carbon dioxide in the atmosphere [1]. (1 gigaton:109) (iii) Total change in carbon dioxide = (119 + 18 + 88 + 6) – (120 + 19 + 90) = 2 gigatons (iv) The oceans act as carbon sinks due to the process of photosynthesis and the solubility of carbon dioxide in water [1]. Carbon dioxide from the atmosphere can dissolve in the ocean water [1] and is used by phytoplankton and algae for photosynthesis [1]. After photosynthesis, carbon compounds is trapped in marine plants and organisms that feed on the plants [1]. When marine plants and animals die and form fossil fuels that are buried in the seabed, carbon compounds are also stored in them [1]. 5 (a) Carbon monoxide competes with oxygen and binds with haemoglobin to form carboxyhaemoglobin in red blood cells. [1] This reduces the ability of blood to transport oxygen to all parts of the body, causing the person to feel tired easily. / Carbon monox