2014 HCI H1 Biology Prelims P1&P2 Answers

HWA CHONG INSTITUTION / 2014 JC2 H1 BIOLOGY / PRELIMINARY EXAMINATION / MARK SCHEME 1 HWA CHONG INSTITUTION 2014 JC2 H1 BIOLOGY PRELIMINARY EXAMINATION MARK SCHEME PAPER 1 Qn No. Correct Answer Qn No. Correct Answer Qn No. Correct Answer 1 B 11 A 21 D 2 B 12 C 22 A 3 B 13 D 23 C 4 A 14 D 24 A 5 C 15 A 25 D 6 D 16 D 26 B 7 B 17 A 27 D 8 B 18 B 28 A 9 D 19 A 29 C 10 A 20 A 30 C PAPER 2 QUESTION 1 (a) (i) Name and state the function of organelles A and B [2] A: Mitochondria, site of cellular respiration to generate ATP B: Nucleus, to store genetic material / DNA. (ii) Explain why there is an abundance of organelle C in the plasma cell. [2] 1. There is an abundance of structure C which is studded with ribosomes. 2. As ribosome is the site of polypeptide synthesis 3. and the ER lumen is the site of protein folding 4. Both are necessary to make large quantity of proteins (b) Explain how the structure of the ce ll membrane relates to its role in maintaining the internal environment of the plasma cell. [3] 1. Structure D is composed of a phospholipid bila yer, with hydrophilic phosphate head and hydrophobic hydrocarbon tails 2. The hydrophobic hydrocarbon tails creates a hydrophobic core 3. The cell membrane is selectively permeable, allo wing desirable substances to be kept within and undesirable substances kept out of the cell 4. It defines the boundary of the cell, keeping the interior of the cell physically separated from the surrounding environment 5. The membrane is fluid, which allows both phospholipids and proteins to move about laterally 6. This allows cell membrane to form pseudopodia to engulf foreign particles 7. Proteins are randomly distributed in the phospholipid bilayer 8. Carrier and channel proteins help to regulate the transport of substrate into and out of the cells 9. Cholesterol is commonly found wedged between phospholipids in cell membrane 10. and regulates membrane fluidity

HWA CHONG INSTITUTION / 2014 JC2 H1 BIOLOGY / PRELIMINARY EXAMINATION / MARK SCHEME 2 (c) Describe how macrophages engulf and digest cellular debris. [3] 1. Macrophage engulfs the cellular debris through endocytosis / phagocytosis 2. The plasma membrane of macrophage ,invaginates / ex tends outwards to enclose, the debris to form vesicles 3. The vesicles pinch off the cytoplasm 4. And may fuse with lysosome which contains hydrolytic enzymes to digest the cellular debris [Total: 10 marks] QUESTION 2 (a) Describe how light is harvested at structures A and B. [3] 1. Accessory pigments embedded in the thylakoid membrane forms the antenna complex of photosystems 2. Range of pigments allow