2024 Dec Revision H2 Ans ASRJC J1 H2 BIO

Anderson Serangoon Junior College Biology Department 1 JC1 December Revision Question 2024 JC1 DECEMBER REVISION–ANSWERS NAME: ………………………………………………… Class: ………………………… Topic: CELLULAR STRUCTURES AND FUNCTION Question 1 [6 marks] TJC Prelims 2009 (a) With reference to Fig. 1.1, suggest the principal function of the pancreatic acinar cell. Give two reasons to explain your answer. [3] Function • secretion of pancreatic / digestive enzymes or secretion of hormones Reasons • presence of large amount of R ER, which is the site where pancreatic enzymes are synthesized • presence of SER, which is the site where steroid hormones / lipids are synthesized • presence of large number of secretory vesicles for release of pancrea tic enzymes/ hormones outside the cell • presence of mitochondria which synthesizes ATP for o Activation of amino acids OR o Formation of peptide bonds (at ribosomes) OR o Transport / Movement of vesicles towards cell surface membrane for r elease of pancreatic enzymes/ hormones (b) (i) Describe two ways in which A is similar to B. [2] • Both are bound by a single membrane / single membrane-bound structures. • Both consist of membranous sacs called cisternae, in which newly synthesized proteins undergo processing. • Both give rise to membrane-bound vesicles which are involved in transport of newly synthesized proteins within the cell. (ii) The products of B are usually in the inactive form. Suggest the significance of this. [1] • to prevent the enzymes (of lysosomes) from digesting proteins / contents within the cells in which they are synthesized

Anderson Serangoon Junior College Biology Department 2 JC1 December Revision Question Topic: BIOMOLECULES AND CELL MEMBRANE Question 2 [11 marks] (a) Draw the resulting maltose molecule arising from a dehydration reaction. [1] (b) Label the resulting bond. [1] • Alpha (1→4) glycosidic bonds Starch, a storage molecule in plants, is a polymer made of glucose molecules joined together. It consists of two components. (c) Name these two components. [2] • amylose • amylopectin (d) (i) Give one similarity between these two components. [1] • contain α-glucose as monomers • coiled into a helix • no cross-linking (ii) Give two differences between these two components. [2] • The amylose component is unbranched whilst the amylopectin component is branched. • The glucose residues in the amylose component are linked by (1→4) glycosidic bonds, whilst the glucose residues in the amylopectin component are linked by both (1→4) glycosidic bonds and (1→6) glycosidic bonds ( at the branchpoints) (f) The following figure shows a section of a cell surface membrane. (i) Explain why membranes are described as fluid mosaic in structure. [2] ‘Fluid’ (any 1) • phospholipids and protein