AS LEVEL BIOLOGY A H020|01 BREADTH IN BIOLOGY THURSDAY 25 MAY – AFTERNOON EXAM CORRECT QUESTIONS AND ANSWERS GRADED A+

AS LEVEL BIOLOGY A H020|01 BREADTH IN BIOLOGY THURSDAY 25 MAY – AFTERNOON EXAM CORRECT QUESTIONS AND ANSWERS GRADED A+ Air moves in and out of human lungs through the trachea, which is lined with cells. The diagram below shows a section containing these cells Which of the following statements about tracheal cells is correct? A Cells X, Y and Z are all columnar epithelial cells. B Cells X and Y move mucus and trapped bacteria out of the trachea. C Cell X releases mucus into the trachea. D Cell Z is a goblet cell. - ANS-C What are the two purines? - ANS-Adenine and Guanine 3 Which of the options, A to D, is a reason why plants require specialized transport tissue? A to allow osmosis to take place B because they all have a large surface area to volume ratio C to carry sucrose to their leaves D to overcome the limitations of diffusion over large distances - ANS-D Many plants are adapted to the availability of water in their environment; one group of these plants is the xerophytes. Which one of the following statements correctly describes a xerophyte? A Smooth cordgrass grows in highly saline marine estuary environments. B The water lily has aerenchyma tissue to allow the movement of gases to submerged roots. C The poison tree has leafless branches covered in thorns to reduce water loss. D Water lobelia completes its entire life cycle submerged in shallow ponds - ANS-C A standard method can be used to extract DNA from the nuclei of cells in kiwi fruit. The statements below list some of the steps involved in this method. Which statement is not correct? A chop the kiwi fruit to break open cell membranes B add detergent to dissolve nuclear membranes C add protease to digest histone proteins D pour ice cold ethanol onto filtrate to precipitate DNA - ANS-A Which of the options, A to D, is a correct statement about polysaccharides of glucose? A Cellulose microfibrils are formed by hydrogen bonding between adjacent chains of α-glucose molecules bonded with 1,4-glycosidic bonds. B Amylose is a straight chain of α-glucose monomers bound by 1,6-glycosidic bonds to allow for dense packing. C Glycogen has a high proportion of 1,6-glycosidic bonds to produce a highly branched molecule for rapid release of α-glucose. D Amylopectin has a mixture of 1,4-glycosidic and 1,6-glycosidic bonds between β-glucose molecules for rapid release of energy - ANS-C Which of the options, A to D, is a correct statement about tissue fluid? A Tissue fluid carries carbon dioxide to muscle cells. B Oncotic pressure in the capillary causes tissue fluid formation from plasma. C Hydrostatic pressure in the capillary causes tissue fluid formation from plasma. D Tissue fluid is reabsorbed into the capillary by active transport - ANS-C Hydrostatic pressure in the capillary causes tissue fluid formation from plasma A group of students was given a 1% solution of an unknown digestive enzyme. They were also given three tubes containing an identical mixture of foods. The students carried out a different biochemical test on each tube before and after adding the unknown enzyme. Their results are shown in the table below (colour before and colour after) Biuret test purple purple Iodine test blue / black yellow / orange Benedict's test brick red brick red Name the type of enzyme the students used. A protease B carbohydrase C lipase D cellulase - ANS-B carbohydrase What is the heart condition represented by the bottom ECG trace? (very rapid, irregular) A fibrillation B tachycardia C ectopic heartbeat D bradycardia - ANS-A- fibrillation A student studied the structure of a blood vessel and found: • an outer layer of collagen fibers, • a thick middle layer of smooth muscle and elastic tissue, • an innermost layer of endothelial cells. Which of the options, A to D, identifies the type of blood vessel the student studied? A artery B capillary C venule D vein - ANS-A- Artery