SUPPLEMENTARY/SECOND OPPORTUNITY EXAMINATION QUESTION PAPER

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1 I nnmibin UNIVERSITY OF SCIENCE nno TECHNOLOGY FACULTY OF HEALTH AND APPLIED SCIENCES DEPARTMENT OF NATURAL AND APPLIED SCIENCES QUALIFICATION: BACHELOR OF SCIENCE QUALIFICATION CODE: O7BOSC LEVEL: 6 COURSE CODE: CEB601S COURSE NAME:CELL BIOLOGY SESSION: JULY 2017 PAPER: THEORY DURATION: 3 HOURS MARKS: 120 SUPPLEMENTARY/SECOND OPPORTUNITY EXAMINATION QUESTION PAPER EXAMINER(S) Prof Percy M. Chimwamurombe MODERATOR: Dr Jeva Kennedy INSTRUCTIONS 1. Answer ALL the questions. 2. Write clearly and neatly. 3. Number the answers clearly. PERMISSIBLE MATERIALS Non programmable Calculators A'I'I'ACHMENT none THIS QUESTION PAPER CONSISTS OF 6 PAGES (Including this front page)

2 By SECTION A: Multiple Choice Section [20] A1 Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. Which of the following canbe described as the smallest living unit? (a) (b) (c) (d) DNA cell organelle protein A2 The flow of genetic information is controlled by a series of biochemical reactions that result in the production of proteins, each with its own specific order of amino acids. Choose the correct series biochemical reactions from the options presented here. (a) replication, transcription, translation (b) replication, translation, transcription (c) translation, transcription, replication (d) translation, replication, transcription A3 Proteins are important architectural and catalytic components within the cell, helping to determine its chemistry, its shape, and its ability to respond to changes in the environment. Remarkably, all of the different proteins in a cell are made from the same 20. linking them in different sequences, the cell can make protein molecules with different conformations and surface chemistries, and therefore different functions. (a) nucleotides (b) sugars (0) amino acids (d) fatty acids A4 A5 Changes in DNA sequence from one generation to the next may result in offspring that are altered in fitness compared with their parents. The process of change and selection over the course of many generations is the basis of. (a) mutation (b) evolution (0) heredity (d) reproduction What unit of length would you generally use to measure a typical human cell? (a) centimeters (b) nanometers (0) millimeters (d) micrometers

3 A6 Cell biologists employ targeted fluorescent dyes proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell. The resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the (a) absorption of light. (b) intensity of light. (c) filtering of light. (d) wavelength of light. or modified fluorescent A7 Prokaryotic cells do not have one of the following (a) a nucleus (b) replication machinery (c) ribosomes (d) membrane bilayers A8 In Prokaryotes, which of the following (a) a highly structured cytoplasm (b) endoplasmic reticulum (c) the ability to divide rapidly (d) a cell wall characteristics are not observed? A9 The is made up of two concentric membranes A10 and is continuous with the membrane of the endoplasmic reticulum. (a) plasma membrane (b) Golgi network (0) (d) nuclear envelope mitochondrial membrane The nucleus, an organelle found in eukaryotic cells, confines the _, keeping them separated from other components of the cell. (a) Iysosomes (b) chromosomes (0) peroxisomes (d) ribosomes A11 Which of the following organelles membrane? (a) endoplasmic reticulum (b) mitochondrion (c) Iysosome (d) peroxisome has both an outer and an inner

4 A12 A13 A14 Mitochondria contain their own genome, are able to duplicate, and actually divide on a different timeline from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are (a) viruses. (b) parasites. (c) endosymbionts. (d) anaerobes. The mitochondrial proteins found in the inner membrane are involved in the conversion of ADP to ATP, a source of energy for the cell. This process consumes which of the following substances? (a) oxygen (b) nitrogen (c) sulfur (d) carbon dioxide Chloroplasts are found only in eukaryotic cells that carry out photosynthesis: plants and algae. Plants and algae appear green as a result of the presence of chlorophyll. Where is chlorophyll located in the chloroplast? (a) in the first, outer membrane (b) in the space between the first and second membranes (0) in the second, inner membrane (d) in the third, innermost membrane A15 Photosynthesis enables plants to capture the energy from sunlight. In this essential process, plants incorporate the carbon from C02 into high-energy molecules, which the plant cell mitochondria use to produce ATP. (a) fat (b) sugar (c) A16 protein (d) fiber The cell constantly exchanges materials by bringing nutrients in from the external environment and shuttling unwanted by-products back out. Which term describes the process of by which external materials are captured inside vesicles and brought into the cell? (a) degradation (b) exocytosis (c) phagocytosis (d) endocytosis A17 are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location. (a) nucleosomes (b) lysosomes (c) peroxisomes (d) endosomes

5 A18 A19 A20 The cytoskeleton provides support, structure, motility, and organization, and it forms tracks to direct organelle and vesicle transport. Which of the cytoskeletal elements listed below is the thickest? (a) actin filaments (b) microtubules intermediate filaments (0) (d) none of the above (all the same thickness) Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton? (a) cell motility (b) vesicle transport (c) membrane support (d) cell division Which of the following characteristics would not support the idea that the ancestral eukaryote was a predator cell that captured and consumed other cells? (a) dynamic cytoskeleton (b) large cell size (0) ability to move. (d) rigid membrane SECTION B [80] B1. Name the enzyme or class of enzyme which: a. Joins the ends of two DNA strands b Forms the RNA primer during DNA replication c. Unwinds the DNA strand during DNA replication d. Able to digest unmethylated DNA e. Protects the single strands from enzyme degradation during DNA replication f. ls involved in supercoiling of DNA 9. Copies DNA in Prokaryotes h. Proofreads and repairs DNA in Prokaryotes 82. Give the complementary, anti-parallel strand for the molecule given below: 5 -AGTTTACAAGGGGAACCG-3 (2) BB. Give any three differences between a prokaryotic cell and a eukaryotic cell. (5) B4. Calculate the surface area to volume ratio of 1 cube of cm in length. (5) BS. Life is a diversity and a unity. Comment on this statement. (5) B6. Briefly explain the cell theory. (4)

6 B7. In a table, indicate the biological functions of the following FIVE cellular (5) structures: a) Golgi apparatus. b) Smooth Endoplasmic Reticulum. c) Nucleolus. d) Vacuole. e) Peroxisome. B8. Describe the cytoskeleton of a cell. (5) B9. Would a small molecule enter a cell by receptor endocytosis? Justify your answer by explaining receptor endocytosis. (1 0) B10. Define the following terms associated with cellular processes: (5) a) Plasmolysis. b) FIaccid. c) Tonicity. d) Co transporter. e) Aquaporin. B11. Describe any SIX functions of cell membranes. (6) B12. What is the difference between hydrogen bonding from van der Waals interactions. (4) B13. What properties of a substance determine whether, and how fast, it will diffuse across the plasma membrane? (10) B14. Distinguish between fats and oils? (5) _ CTION C [29] C1. The process of photosynthesis is probably the single most important life-giving cellular process. Comment on this statement describing the process of photosynthesis. (20) ---END OF EXAMINATION PAPER------