Tut 1 - Cell Ultrastructure (Student)

St Andrew’s Junior College Cell Ultrastructure 2021 H2 Biology 1 Full Name: Civics group: 21S Index no.: Date: Core Idea 1: The Cell and Biomolecules of Life Tutorial 1 Cell Ultrastructure MCQ ANSWERS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 Which size ranges can be viewed using a light microscope? A 4 only B 1 and 2 only C 2 and 3 only D 3 and 4 only 2 The diagram shows a chloroplast drawn from an electronmicrograph. The length of the chloroplast from X to Y is 5000 nm. What is the magnification of the drawing of the chloroplast? A x100 B X1000 C X10 000 D X100 000

St Andrew’s Junior College Cell Ultrastructure 2021 H2 Biology 2 3 The electronmicrograph is of a chloroplast. The length of the chloroplast image along the line shown is 90 mm. T he magnification of the organelle is x300,000. What is the actual length of the chloroplast? A 0.3 µm B 3.0 µm C 30 µm D 300 µm 4 You are told that the cells on a microscope slide are plant, animal, or bacterial. You look at them through a microscope and see cell walls and membrane-bound organelles. You conclude that the cells are A Bacteria cells B Plant cells C Bacteria and plant cells D Bacteria, plant, and animal cells

St Andrew’s Junior College Cell Ultrastructure 2021 H2 Biology 3 5 Which features enable an organism to be identified as a prokaryote? 1 cell wall 2 circular DNA 3 nucleus 4 ribosomes A 2 only B 3 only C 1 and 4 only D 2 and 4 only 6 A scientist carried out an experiment to separate the organelles in an animal cell by mass. The scientist mixed the cells with a buffer solution which had the same water potential as the cells. He then broke the cells open with a blender to release the organelles. The extracted mixture was filtered and then spun in a centrifuge at a high speed to separate the heaviest organelle. This sank to the bottom, forming a solid pellet, 1. The liquid above pellet 1 was poured into a clean centrifuge tube and spun in the centrifuge at a higher speed to separate the next heaviest organelle. This organelle sank to the bottom, forming a solid pellet, 2. He repeated this procedure twice more to obtain pellet 3 and pellet 4, each containing a single organelle. What is the function of the organelle extracted in pellet 2? A digestion of old organelles B production of ATP C production of mRNA D synthesis of protein

St Andrew’s Junior College Cell Ultrastructure 2021 H2 Biology 4 In-class activity Arrange the following organelles in the order that they will be separated via cell fractionation: Endoplasmic reticulum, chloroplasts, nucleus, ribosomes, lysosomes, mitochondria 1 What do 70S and 80S mean? S = sedimentation coefficient of a particle (its behaviour during a sedimentation process – centrifugation) What is centrifugation? Application of the centripetal force for the sedimentation of mixtures with a centrifuge Bigger particles sediment faster and have higher sedimentation coefficient. Thinking questions: 1. What do 70S and 80S mean? 2. And why does 30S+50S not add up to 70S, and 40S+60S not add up to 80S?

St Andrew’s Junior College Cell Ultrastructure 2021 H2 Biology 5 2 And why does 30S+50S not add up to 70S, and 40S+60S not add up to 80S? Sedimentation coefficients are not additive (they do not add up together). This is because they represent a rate of sedimentation, and the rate of sedimentation of a molecule depends upon its size and shape, rather than simply its molecular weight. 7 The electronmicrograph shows part of two cells. Which of the labelled features enable these cells to be identified as eukaryotic? A W only B X only C W and X only D W, X and Y

St Andrew’s Junior College Cell Ultrastructure 2021 H2 Biology 6 8 The electronmicrograph shows part of a cell. Which organelles shown in the electronmicrograph have more than one membrane? A 1, 2 and 5 B 1, 3 and 5 C 2, 3 and 4 D 3, 4 and 5 9 What is the function of nucleoli? A formation and breakdown of the nuclear envelope B formation of centromeres C formation of ribosomes D formation of the spindle during nuclear division 10 Which cell organelles contain DNA? 1 centriole 2 mitochondrion 3 nucleolus 4 ribosome A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

St Andrew’s Junior College Cell Ultrastructure 2021 H2 Biology 7 11 Which statement is correct? A Prokaryotes and chloroplasts have circular DNA where genes carrying the code for cell walls are located. B Prokaryotes and chloroplasts have 70S ribosomes that are the sites for translation and polypeptide synthesis. C Prokaryotes and mitochondria have an outer membrane and a separate inner, folded membrane where ATP synthesis occurs. D Prokaryotes and mitochondria have double -stranded linear DNA where genes carrying coded information are located. 12 A gland cell capable of producing la rge quantities of sex hormone testosterone would be likely to have well developed A Lysosome B Centrioles C Rough endoplasmic reticulum D Smooth endoplasmic reticulum 13 Where are cisternae found in a cell? 1 endoplasmic reticulum 2 Golgi body 3 mitochondrion A 1 and 2 B 1 and 3 C 1 only D 2 and 3 14 Which of the following statements correctly characterize(s) bound ribosomes? 1 Bound ribosomes are enclosed in their own membrane. 2 Bound ribosomes are structurally different from free ribosomes. 3 Bound ribosomes are concentrated in the cisterna space of rough endoplasmic reticulum. 4 Bound ribosomes generally synthesize membrane proteins and secretory proteins. A 4 only B 1 and 3 C 2 and 4 D 3 and 4

St Andrew’s Junior College Cell Ultrastructure 2021 H2 Biology 8 15 The electron micrograph below depicts organelle X. Which of the following options is not a function of organelle X? A Chemical modification of proteins B Synthesis of steroids C Formation of secretory vesicles D Formation of lysosomes 16 The photo electron micrographs show early and late stages in the development of the cell wall in a young plant cell. Which statement describes the events leading to the development of the cell wall? A Complex carbohydrates assembled in the Golgi body are exported to the cell wall by the Golgi vesicles. B Enzymes in the cell surface membrane synthesise the cell wall components from soluble carbohydrates brought by the Golgi vesicles.

St Andrew’s Junior College Cell Ultrastructure 2021 H2 Biology 9 C Polysaccharides are exported to the ce ll wall and synthesized into wall components by the Golgi body. D Ribosomes synthesise glycoproteins that are exported by Golgi vesicles to be used in the cell wall. STRUCTURED QUESTIONS QUESTION 1 Each of the statements A – C describes a structure found in eukaryotic cells. (a) Identify the structure that is described in each statement. [3] (i) A thread-like structure composed of DNA and histone proteins. ............................................................................................................................... (ii) The structure in which rRNA is synthesised and combined with proteins. ............................................................................................................................... (iii) The structure occur in pairs at each pole and their position is important in determining the polarity of the cells during mitosis. ............................................................................................................................... (b) One theory about the evolution of organelles is the endosymbiotic theory. This theory suggests that the mitochond