BIO251 EXAM 1 PRACTICE QUESTIONS 2023

BIO251 EXAM 1 PRACTICE QUESTIONS 2023. A cotton fiber consists mainly of cellulose, whereas a potato tuber contains mainly starch. Cotton is tough, fibrous and virtually insoluble in water. The starch present in a potato tuber is neither tough nor fibrous and can be dispersed in hot water to form a turbid solution. Your friend says that this is because starch and cellulose are made of monomers with vastly different properties. You need to set your friend straight. How would you go about doing this? Cellulose and starch are both polysaccharides present in most plants and are made up of glucose monomers. Cellulose serves as structural support in plant cell walls while starch serves as an energy store. Their difference in properties has to do with their structure which is directly influenced by their different bonding patterns. Cellulose is composed of long straight chains that combine via hydrogen bonds to form tight, sturdy bundles; however, Starch, on the other hand, has a covalent bonding pattern that results in a spiral/coil structure. 2. Each of the following medical problems involves a disorder in the function of an organelle or other cellular structure. In each case, identify the organelle or structure involved and indicate whether it is likely to be underactive or overactive. a) A smoker develops lung cancer and is told that the problem is a population of cells in her lungs that are undergoing mitosis at a much greater rate than normal. Cell division is controlled very carefully during the cell cycle. The nucleus is responsible for control during mitosis (M phase of the cell cycle), and since the rate of mitosis is higher than normal, the nucleus is likely overactive.