2018 Eukaryotic Cell Structure & Cell Membrane STQ QP.pdf

2018 Eukaryotic Cell Structure and Cell Membrane STQ 2018 / H2 / ACJC PRELIM / P2 Q11Cholesterol is synthesised in the smooth endoplasmic reticulum (SER) in liver cells by a series of enzyme-catalysed reactions. Cholesterol is then transported to the Golgi apparatus where they are packaged into vesicles and subsequently released into a membrane-bound duct of the liver. Fig. 1.1 is an electron micrograph of a section of a liver tissue. Fig. 1.1(a)Name structure T in Fig. 1.1 and describe its role in liver cells.[2](b)Both prokaryotes and structure T have membrane proteins to help them perform the role described in (a). Suggest how prokaryotes perform this role. membrane-bound duct ofliverT cholesterol

[3](c)Describe the role of cholesterol in the cell surface membrane.[1](d)Suggest how cholesterol is transported from the Golgi apparatus to the membrane-bound duct of the liver.[2] [Total: 8]2018 / H2 / IJC PRELIM / P2 Q12Fig. 1.1 shows an electron micrograph of a pancreatic cell that secretes large amounts of insulin that helps to regulate blood glucose level. A Fig. 1.1(a)With reference to Fig. 1.1, (i)identify organelle A;[1](ii)describe two identifying features of organelle A that allows its identification in (a)(i).

[2] Fig. 1.2 shows a diagram of the molecular structures of tristearin (a triglyceride) and phosphatidylcholine (a phospholipid). Fig. 1.2(b)Table 1 shows a structural difference between the two molecules shown in Fig. 1.2.Complete Table 1 with two further structural differences other than in numbers of different types of atoms.

Table 1structural featuretristearinphosphotidylcholinelength of fatty acid chainall same lengthdifferent lengths[2](c)Triglyceride is used as energy storage while phospholipids are membrane components. Explain why phospholipids are suitable membrane components but not triglyceride.[2]Cells in the pancreas secrete enzymes, such as amylase and trypsin, into a duct. The enzymes are packaged in vesicles so that they can be exported from these cells as shown in Fig. 1.3.

(d) (d) Fig. 1.3(d)On Fig. 1.3, label the cytoplasm of the cell as 'cytoplasm' and extracellular fluid as 'extracellular'. [1](e)With reference to Fig. 1.3,(i)explain how enzymes that are secreted by cells in the pancreas are packaged into vesicles and exported, after their synthesis at the endoplasmic reticulum.

[6](ii)explain one property of the plasma membrane that allows vesicle formation.[2](f)Describe two advantages of having plasma membranes within the cell.[2][Total: 18]2018 / H2 / MJC PRELIM / P2 Q1

QUESTION 3Fig. 1.1 is an electron micrograph of part of a eukaryotic cell. Fig. 1.1(a)Identify the structures J and K. [2]J ……………………………………………………………………………………………..K ……………………………………………………………………………………………..(b)Describe two structural features shown in Fig. 1.1 that identify G as the Golgi appar