NYGH 2016-S3EOY-Bio P1 and P2 Ans

1 NANYANG GIRLS’ HIGH SCHOOL End-of-Year Examination 2016 Secondary Three BIOLOGY Paper 1 1 D 7 D 13 C 19 C 25 B 2 B 8 A 14 B 20 D 26 A 3 A 9 C 15 D 21 A 27 D 4 B 10 A 16 C 22 D 28 B 5 C 11 A 17 D 23 D 29 C 6 D 12 D 18 B 24 B 30 B Qn Ans Explanation 1 D Ribosome makes protein and rough endoplasmic reticulum transports protein. Mitochondrion releases energy by respiration. Vacuole stores substances in the cell. 2 B Xylem vessels on the right are younger and broader to transport more water so option D is wrong and option B is correct. Lignin deposit has nothing to do with xylem vessels dying or losing water. 3 A At 50% plasmolysed cells, water potential inside and outside the cell are the same hence no net gain or loss in water molecules. Reject: option B and option D because if concentration inside all the cells are greater than sucrose concentration outside then water will enter cells. Reject: option C because 100% of plasmolysed cells does not mean cells are at equilibrium with solution outside cell 4 B Once the HIV bind to the receptor on the cell membrane, endocytosis takes place. 5 C The number of denatured enzyme molecules will increased after optimum temperature X °C so option C is correct. Option A is wrong, as activation energy should be at minimum with the help of enzyme. Option B is wrong, as kinetic energy will still increase with increase in temperature. Option D is wrong, as number of E-S complex is increasing. 6 D Only option D is an observation hence correct. The other 3 options are all inferences and there is not enough information for such inferences. 7 D Amino acids are linked by peptide bond to form a linear chain in the primary structure instead of hydrogen bond. Option A is wrong as hydrolysis reactions break bonds and not link amino acids 8 A Hydrocarbon chains of molecule X may be from saturated or unsaturated fatty acids hence any option with statement 3 will be wrong. 9 C Only amino acid contains nitrogen so only option C is correct. 10 A Chlorophyll absorbs blue and red regions of the light spectrum so only option A is correct.

2 11 A Hydrogen ions will reduce carbon dioxide into carbohydrates during the light independent stage. 12 D Excess glucose will be converted to amino acids and transported out of the leaf via phloem as shown in option D. 13 C Option C is the independent variable and not a controlled variable so it is wrong. 14 B Photolysis of water takes place in the granum which is option B. 15 D Only option D shows correct sequence. 16 C Option C shows the endodermis with Casparian strip hence is able to regulate ions entry. 17 D Option D refers to the capillary action that draws water up the xylem during transpiration. Option A is wrong, as osmosis is involved. Option B is wrong, as water remains as liquid at 4 degree Celsius at the bottom of the lake and is not due to the adhesive and cohesive property of water. Option C is wrong, as the property of water as solvent is used here. 18 B When transpiration exceeds water uptake, as seen at noon, plant cells will be flaccid hence option B is wrong. Option A is a correct fact BASED on graph as rate of water uptake is more than rate of transpiration 19 C Structure R shows the pancreas. The pancreatic juice contains amylase, trypsin and lipase. At the same time, islets of Langerhans in the pancreas produces the hormone insulin. 20 D The peak concentration of the drug in the blood was achieved at about 1 hour, after which the concentration drops rapidly. As food usually stays in the stomach for about 2 to 4 hours after consumption, it is highly unlikely that the drug would have entered the ileum within the first 2 hours after consumption. This means that the drug must have been absorbed by the stomach, before it had the opportunity to reach the ileum. Absorption does not take place in the oesophagus. 21 A For drug W to be absorbed into the bloodstream without its properties changing, it must be resistant to action of pepsin or the enzyme in the stomach will cause the drug to be altered. Option B is wrong because if drug is broken down by acid then it will not be useful as a drug If the drug is made up of large, insoluble molecules, it would not be able to be absorbed. If the drug is coated with a chemical that sticks to the mucus, it is highly likely that the chemical will not be absorbed but instead remain trapped in the mucus lining. 22 D This experiment shows the test for starch, so solution X must be iodine solution. 23 D This experiment shows the test for starch, where solution X is iodine solution. The area surrounding well 2 shows that the iodine solution remained brown, indicating the absence of starch. Starch must thus have been digested in the presence of amylase. Options 1 and 2 are incorrect as amylase is not present (option 1 and option 2). Amylase can be found in both pancreatic juice and saliva, thus options 3 and 4 are correct. 24 B J shows a red blood cell (erythrocyte). K is a platelet while L shows a white blood cell (leucocyte). This particular type of leucocyte is known as a neutrophil.

3 25 B Soluble protein S is cleaved then combined to form insoluble threads T – this indicates that fibrin threads are formed (T). S must thus be fibrinogen. Chemical U is the enzyme that catalyses this cleavage, and is therefore thrombin. 26 A The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs, and must thus carry the lowest concentration of oxygen as compared to other blood vessels. 27 D The volume of blood pumped per minute during rest is 60x50=3000 cm3/min The volume of blood pumper per minute during vigorous exercise is 200x75=15000 cm3/min So there was an increase in 15000cm3/3000cm3= 5.0 times volume. Option A 75/50=1.5 times has error in calculation since only raw vol of blood per beat was used Option C is also wrong as Q asked for comparison between volume of blood at rest and during exercise. Q did not ask to compare ‘difference’ so cannot use 15000-3000. 28 B The semi-lunar valve between the aorta and left ventricle closes when the pressure in the aorta is higher than that of the ventricle. This occurs at times 0.24 seconds and 0.70 seconds, thus the semi-lunar valve is closed for 0.70-0.24 = 0.46 seconds. 29 C P represents the trachea, which then leads to the 2 bronchi (plural form of bronchus). The bell represents the rib cage, while the rubber sheet represents the diaphragm. The balloon represents the lungs. 30 B The rate of anaerobic respiration must increase in order to increase rate of ethanol production. This can be done by increasing the concentration of substrate available, in this case, glucose. Adding of oxygen into the mixture will prevent anaerobic respiration from taking place. Solution N is used to detect the presence of carbon dioxide and will not affect the rate of ethanol production, while maintaining the temperature at 85oC would probably cause the yeast to die as the temperature is too high.

4 Paper 2 Section A 1 (a) (i) During (aerobic) respiration in mitochondrion; energy is released; Max 2 Accept: This energy may be used by the cell to perform cell activities such as growth / reproduction /active transport (ii) Marker’s comment: ‘Compare’ type of Q needs the answers to be done factor by factor. Do not write two separate sentences or paragraphs and then expect your marker to sieve out the comparisons. Y is highly folded but X is not folded; Y increased surface area to volume ratio as compared to X; Y functions for attachment of enzymes but X functions as a barrier; Max 2 Reject: X is outer membrane but Y is inner membrane / cristae (Q did not ask for location) Reject: X is selectively permeable but Y is not permeable (all membranes are selectively permeable) Accept: X encloses contents of mitochondrion but Y is the site for oxidative phosphorylation and electron transport ch