Biology Assignments - Assignment Example

Biology Assignments College Question a i. Experiment A was set without carbohydrate because it was to act as a control experiment to show that carbohydrates are required for the fermentation process to take place. He expected no reaction to take place in the bottle (Madigan, Martinko and Parker 7). ii. According to the graph, there was considerable reaction in experiment A as fermentation could not take place without a carbohydrate. In experiment B conducted with glucose, it is seen that the lag phase took about five minutes, after which the fermentation process increased for the next 30 minutes. Glucose is a monosaccharide that is easily utilized by yeast in the fermentation process. Unlike other complex sugars, glucose readily begins gylcolysis. In experiment C, the yeast was incubated with sucrose, a disaccharide that must be broken into glucose and fructose first. Yeast cells possess the invertase enzyme that s used to break down sucrose into fructose and glucose. This often takes place outside the yeast cell. The yeast then consumes the glucose first followed by fructose. The resultant curve is comparable to that of glucose though the gycolysis takes place at a slightly slower rate. There was no fermentation in experiment D and, therefore, the curve did not form. The primary reason for that is because Saccharomyces cerevisiae does not produce the enzyme required to break down starch. Some fungal species possess alpha-Amylase, an enzyme that can break down starch into simpler sugars (Yeast Fermentation with Different Carbohydrates, par. 2). In experiment D, the student added amylase to the yeast and starch suspension. Amylase acts on long starch chains, breaking them into maltose and maltotriose. Unlike in experiment C, the amylase added to experiment D was able to break down the starch into simpler sugars that can be digested by Saccharomyces cerevisiae. The resultant curve has a longer log phase which lasts for a about 10 minutes. This is the time taken for amylase to break down sufficient amounts of starch for fermentation to begin. The curve does not attain the same levels as that of glucose (Ethanol production by yeast fermentation: Experimental concept,4). Question 1b The optimum temperature required by Saccaromyces cerevisiae is 31 to 32 Degrees Celsius. Increasing or lowering the temperatures will have a negative effect on the rate of fermentation. i. At 4 °C, there will be no fermentation activity as the temperatures will be too cold for the yeast’s metabolic processes. The ii. At 60°C the temperatures will be too high for the yeast cell’s metabolic processes and the fermentation will be slowed down. Question 2 a. The primary consumers in the food chain are herbivorous zooplanktons b. The photosynthetic phytoplankton in the water is autographs as they produce energy using sunlight and carbon dioxide. c. A very small fraction of the sunlight energy is used for photosynthesis by the phytoplankton because optimal solar radiation is required for photosynthesis, and not all solar radiation is within the required wave length (Boyce, Lewis and Warm 592). The radiation from the sun is also too much for photosynthesis and must be dissipated to avoid causing damage to the photosynthetic apparatus. Excess energy from incoming sunlight is lost through reflection and heat. d. Percentage of solar energy falling on the surface of water that is lost = (1.2*106KJ m-2 y-1) – (6.3*103KJ m-2 y-1) =1.1937*106KJ m-2 y-1 = (1.1937*106KJ m-2 y-1 ÷1.2*106KJ m-2 y-1) * 100 99.5% e. The amount of energy lost through the ecosystem through zooplankton respiration. Energy consumed by plant respiration = GPP-NPP 6.3*103KJ m-2 y-1 - 5.0*103KJ m-2 y-1 = 1.3*103KJ m-2 y-1 Question 3 a. Alfred is Xb Y because he has suffers from the vision deficiency which requires the recessive alleles to be expressed phenotypically. Furthermore, the condition is inherited by Keith (second generation offspring). This implies that he contributed a recessive allele that combined with another recessive allele in the 2nd generation parents to lead to the phenotypic expression of the condition in Keith. Diana is Xb XB because she does not have the color vision deficiency but one of her off springs has it. This implies that she contributed one of the two recessive alleles required for the condition to be expressed phenotypically in Holly. Fiona is Xb XB this is because the vision deficiency is expressed in one of her grandsons. The condition is not expressed in her first generation offspring who also has Xb XB. b. i. genetics cross diagram XBY XBXb XBXB XB Xb Y XB YXb i. According to the layout there are two male off springs and two female off springs. One of the male off springs has the color deficient condition while the other is normal. Therefore the probability that Paul has the condition is 50%. ii. According to the cross diagram the recessive color allele is present in two out of the four children, one male and one female. The probability that any of their children will carry the recessive color allele is 50%. iii. The fact that Ivan and Jenny have two boys and a girl will not determine the sex of their next child. The cross diagram shows that any birth can result into 50% probability of a girl and 50% for a boy. Therefore, the probability that their next child will be a girl is 50%. Question four A i. Amino acid sequence resulting from each of the sections of mRNA Section of normal mRNA sequence: …CAC CUG ACU CCU GAG GAG AAG UCU GCC… Section of mutant mRNA sequence: …CAC CUG ACU CCU GUG GAG AAG UCUGCC… For normal mRNA sequence Proline-Serine-Threonine-Proline-Glycine-Glutamic Acid-Lysine-Leucine For Mutant nRNA sequence - Proline-Serine-Threonine-Proline-Glutamic Acid-Glutamic Acid-Lysine-Leucine ii. A change in the Amino acid sequence affects its function as a result of the following: the amino-acid sequence determines the function of the protein. When the amino acid sequence changes, the function of the protein automatically changes. Another explanation is that proteins are complex structures with each protein possessing a unique three dimensional shape (Griffiths, Miller and Suzuki 77). The protein has to fold up correctly in order to carry out its function. The protein is held in shape by the bonds formed by different amino acids. When a wrong amino acid is present, the bond is not formed the same way and, therefore, the protein fails to perform its function (Sanger, Nicken and Coulson 5465). iii. A mutation that causes deletion of a base in the DNA coding for protein s usually more damaging than one that causes the substitution of one base for another because a substitution changes a single base only and therefore, changes one amino acid. If such a substitution takes place at a non-coding part then it won’t result in any harm (Sanger, Nicken and Coulson 5466). On the other hand, a deletion will result into a frame shift and this will affect the entire sequence. Question four b How could natural selection increase the number of children born with sickle-cell disease in certain regions when these individuals are unlikely to survive and produce offsprings. Natural selection is described as the gradual, yet non-random process by which biological tress are either increased or reduced in a populatation (Christiansen 64). The term was coined and popularized by Charles Darwin (Christiansen 65) The concept of fitness is paramount in the natural selection process. Individuals that are more “fit” have a higher potential to survive when compared to others. Fitness, is currently described as a measure of how successful an organism produces rather than how long it lives. Sickle cell is described as common genetic condition that takes place when an offspring inherits mutant haemoglobin genes from both parents (World Health Organization). About 300,000 children are born with haemoglobin disorders around the world, and more than 200,000 cases of sickle cell disease are reported in Africa. The relatonship between sickle cell disease and malaria in some regions of Africa provides an interesting account of how natural selection increases the number of people with genes that pridispose them to a given condition. The frequency of the gene mutation that causes sickle cell is much higher in Subsaharan Africa . Carriers of the mutant gene are unevenlyt distributed on the continent, with rates going to as high as 40% in equatorial Africa and as low as Read More