2018 Eukaryotic Cell Structure & Cell Membrane STQ QP

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 apparatus and not the rough endoplasmic reticulum. [2]1.…………………………..…………………………………………………………………………… ……………………………………………………………………………………..…………………2.…………………………………………………………………………………………..…………… ……………………………………………………………………………………………..…………

The Golgi apparatus is an organelle that is important for many functions. One example is the formation of lysosomes. Before lysosomal hydrolases can function in the lysosome, they must be sorted from other proteins. Fig. 1.2 shows how a glycosylated lysosomal hydrolase is sorted at the trans face of the Golgi apparatus. Fig. 1.2(c)Outline the pathway taken by the lysosomal hydrolase from its site of synthesis to the trans face of the Golgi apparatus. [3]……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..(d)With reference to Fig. 1.2, suggest how the Golgi apparatus is able to specifically sort the lysosomal hydrolase from other proteins. [2]……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..[Total: 9]

2018 / H2 / MJC PRELIM / P2 Q2QUESTION 4(a)Contrast the processes of facilitated diffusion and active transport.[3]……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..……………………………………………………………………………………………………………..(b)A group of students investigated the uptake of chloride ions in barley plants. They divided the plants into two groups and placed their roots in solutions containing radioactive chloride ions.Group A plants had a substance that inhibited respiration added to the solution.Group B did not have the substance added to the solution.The students calculated the total amount of chloride ions absorbed by the plants every 15 minutes. Their results are shown in Fig. 2.1. Fig. 2.1(i)Calculate the ratio of the rate of uptake of chloride ions in the first hour to the rate of uptake of chloride ions in the second hour for group B plants.[2]Ratio: …………………………………..

(ii)Explain the results shown in Fig. 2.1.[4]………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………………………………………………………………………………………………...………………………………………………………………………………………………………...[Total: 9]2018 / H2 / NJC PRELIM / P2 Q15Fig. 1.1 shows a section of a cell surface membrane.CBA DFig. 1.1(a)Name the structures labelled A, B, C and D.ABCD[2]