HOMEWORK ANSWERS

CHAPTER 5 HW ANSWERS:

Self Test 1). What type of microscope would you need to view a cellular structure that is 5 nm in size?     a). a light microscope     b). an electron microscope     c). a compound microscope     d). no microscope can resolve down to 5 nm Answer: b 2). Which of the following is not found in prokaryotic cells?     a). ribosomes     b). cell wall     c). nucleus     d). photosynthetic membranes Answer: c 3). Which of the following statements is incorrect.     a). DNA in the nucleus is usually coiled into chromosomes.     b). The nucleolus is the site of ribosomal RNA synthesis.     c). Some substances can pass into and out of the nucleus.     d). Red blood cells can not synthesize RNA. Answer: a 4). Which of the following matches are not correct.     a). ribosomes -- rough ER     b). protein synthesis -- smooth ER     c). rough ER -- export of proteins out of cell     d). smooth ER -- cells in intestine Answer: b 5). Which is the following is not produced by the Golgi apparatus?     a). glycolipids     b). glycoproteins     c). liposomes     d). secretory vesicles Answer: c 6). What is the difference between a primary lysosome and a secondary lysosome?     a). Primary lysosomes are larger than secondary lysosomes.     b). Primary lysosomes are active, while secondary lysosomes are inactive.     c). Primary lysosomes have a low pH while, secondary lysosomes have a high pH.     d). Primary lysosomes have low levels of protons, while secondary lysosomes have high levels of protons. Answer: d 7). Proteins that stay within the cell are produced     a). on free ribosomes in the cytoplasm.     b). in the nucleolus.     c). on ribosomes attached to rough ER.     d). on ribosomes and pass through the Golgi apparatus. Answer: a 8). What do chloroplasts and mitochondria have in common?     a). Both are all present in animal cells.     b). Both contain their own genetic material.     c). Both are present in all eukaryotic cells.     d). Neither is present in plant cells. Answer: b 9). Which of the following pairs is correctly matched?     a). actin–MTOC     b). intermediate fibers–protofilaments     c). microtubules--"+" / "-" ends     d). intermediate fibers –cellular movement Answer: c 10). Which of the following eukaryotic organelles are believed to have evolved through endosymbiosis?     a). nucleus and mitochondrion     b). mitochondrion and chloroplast     c). nucleus and endoplasmic reticulum     d). chloroplast and endoplasmic reticulum Answer: b Test Your Visual Understanding 1). From the following list, match the correct label with its numbered leader line in the figure, and describe the function of the organelle in the eukaryotic cell. cytoskeleton mitochondrion nuclear envelope nucleolus ribosomes rough endoplasmic reticulum smooth endoplasmic reticulum Answer: 1). 1--Nuclear envelope, function is to control the transport of materials into and out of the nucleus. 2--Nucleolus, function is the localization of DNA that encodes hundreds of copies of rRNA, which allows the rapid generation of large numbers of the molecules needed to produce ribosomes. 3--Smooth ER, function is the synthesis of carbohydrates and lipids. 4--Cytoskeleton, function is the support the shape of the cell, to transport materials throughout the cell, and to move the cell. 5--Mitochondrion, function is the cite of oxidative metabolism in the cell. 6--Rough ER, function is the synthesis of proteins destined to be exported from the cell. 7--Ribosomes, function is the translation of RNA copies of genes into proteins. Apply Your Knowledge 1). White blood cells (WBCs) circulate throughout the human body. Monocytes make up about 6% of total WBCs, and neutrophils make up about 65% of total WBCs. Monocytes have a diameter of 15 µm, and neutrophils have a diameter of 10 µm. Calculate the surface area and volume of each cell. Answer: 1). The equation for the surface area of a sphere is 4pr2 The equation for the volume of a sphere is 4/3pr3 To calculate either the surface area or volume, we must determine the radius of each cell: r = 1/2 d (where r is radius and d is diameter) such that:     radius of monocyte = 1/2 (15) or r = 7.5 µm     radius of neutrophil = 1/2 (10) or r = 5 µm Surface area:     Surface area of monocyte = 4pr2 or 4p7.52 or 4p56.25     Surface area of monocyte = 706.5 µm2     Surface area of neutrophil = 4pr2 or 4p52 or 4p25     Surface area of neutrophil = 314 µm2 Volume:     Volume of monocyte = 4/3pr3 or 4/3p7.53 or 4/3p421.875     Volume of monocyte = 1766.25 µm3     Volume of neutrophil = 4/3pr3 or 4/3p53 or 4/3p125     Volume of neutrophil = 523.33 µm3

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