BSC 2010L Final exam questions with 100% Verified

What is a spectrophotometer? What does it measure, and how is it measured? - Correct Answers Spectrophotometer is an instrument used to measure the amount of light that is absorbed or transmitted through a sample, at a particular wavelength of light. measures either the amount of light absorbed or the amount of light transmitted What is an absorption spectrum? What value for a substance can be determined by plotting its absorption spectrum? - Correct Answers Absorption spectrum is the pattern of light absorption over a range of wavelengths for a particular substance. Can determine the wavelength of maximum absorbance by the substance. What is a standard curve? How can it be used to find the concentration of an unknown substance? - Correct Answers A standard curve is a plot of the known concentration with the series of a sample against their relative absorbance. Can be used to find an unknown concentration of a sample. What is a hypothesis? Why must it be falsifiable? - Correct Answers A hypothesis is an explanation of an observation that must be tested and a conclusion must be formed. it can be tested in a way that can lead to evidence that does not support the hypothesis. Know the meaning of a control, independent variable, dependent variable. - Correct AnswersControl: the group in an experiment or study that does not receive treatment by the researchers and is then used as a benchmark to measure how the other tested subjects do. Independent variable: variable being changed or controlled by the investigator. Dependent variable: variable being measure/tested Understand the terms magnification, resolution, contrast, depth of field and index of refraction, and explain how each can be modulated in light microscopy. - Correct AnswersMagnification: the number of times larger an image appears than its real sizeCAN BE CHANGED WITH OBJECTIVE LENSES OR coarse/fine adjust knobs Resolution: the ability for the microscope to see detail. Adjusting the condenser can be an effective way to improve image quality/focusing knobs Contrast: Difference in brightness between light and dark areas. can be modulated with condenser knob Depth of field: The vertical distance that can brought into focus. objectives can be used to show different depths of field. Index of refraction: a physical property defined by the speed of light in a vacuum divided by the speed of light in the medium Know how to calculate the total magnification and the diameter of the field of view. Know how to estimate the size of a cell depending upon the magnification and diameter of the field of view - Correct Answersthe objective lens times 10x in 10x objective, it is 2mm. you find the amount of cells crossing the whole view, and do 2 divided by the amount across, which will give x mm. 4x=4mm, 10x=2mm, 40x=.4mm, 100x=.2mm Be able to interconvert between the following metric units: meters, mm and μm, and liters, ml, μl. - Correct Answers1,000mm in 1m 1,000μm in 1mm 1,000,000μm in 1m 1,000mL in 1m 1,000μL in 1mL 1,000,000μL in 1L Be able to summarize the differences between prokaryotic and eukaryotic cells. - Correct AnswersProkaryotic cells • no nucleus, the nucleoid holds the most of the DNA • no membrane bound organelles • 1-10μm Eukaryotic cells • presence of nucleus, the nucleus holds most of the DNA • presence of membrane bound organelle • 10-100μm Be able to explain why cell size is limited by the surface area-to-volume ratio. Understand the mechanisms larger cells such as those found in plants use that allow them to survive. - Correct AnswersAs size increases the surface area to volume ratio decreases, so larger cells have more trouble obtaining enough nutrients and ridding themselves of waste -Central vacuole-Cytoplasmic streaming Be able to explain the endosymbiont theory for how certain eukaryotic organelles originated. What evidence exists to support the theory? - Correct AnswersThe concept that mitochondria and chloroplasts evolved from an endosymbiotic relationship between a prokaryotic cell and an ancestral eukaryotic cell. Evidence: both have double membrane, similar size, have circular DNA, semi autonomous. What is diffusion? What is meant by diffusion down a concentration gradient? What is dynamic equilibrium? How does heat affect the rate of diffusion? - Correct AnswersDiffusion: A random movement towards a state equilibrium from high concentration to lower concentration. Diffusing down a gradient is where a substance will diffuse from a more concentrated area to less concentrated area. Dynamic equilibrium: molecules equally dispersed throughout an area. Diffusion increases as temperature increases What is osmosis? Explain what is meant when a cell's environment is referred to as hypertonic, hypotonic, or isotonic? How does each affect a plant cell? An animal cell? How do animal cells, plant cells, protists and bacteria each deal with the problem of osmosis? - Correct AnswersOsmosis: The diffusion of water across a semi-permeable membrane. Hypertonic: solution w/higher solute concentration Hypotonic: solution w/lower solute concentration Isotonic: solution w/equal concentration plant/bacteria= cell wall, animal= osmoregulation flushes out the amount of water and salt in blood. , protist=contractile vacuoles How can an osmometer be used to test the solute concentration of a solution? - Correct AnswersOsmometer is used to measure movement of water across a semi-permeable membrane Be able to explain what pH means. Be able to describe how Paramecia and hypermastigotes differ in their sensitivity to environmental pH. - Correct AnswerspH is a measure of the concentration of hydrogen ion in a solution. pH=7 is neutral pH 7 is acidic pH 7 is basic Why were DNA-containing solutions kept on ice throughout the lab exercise? - Correct AnswersTo slow down the metabolism of the cell so the DNA doesn't die. The cold will increase the amount of DNA. cyanobacteria - Correct Answersprokaryotic cell/ lines or string made by circle/photosynthetic elodea - Correct Answerseukaryotic cell/ green brick/photosynthetic potato cell - Correct Answerseukaryotic/ hexagon background with bubbles amoeba - Correct Answerseukaryotic cell/ branch like parameceim - Correct Answerseukaryotic cell/ oval with dots inside lactobacillus - Correct Answersprokaryotic cell/ few black dots yeast - Correct Answerslittle clear bubbles Write the equations summarizing the overall processes of aerobic cellular respiration and alcohol fermentation. - Correct AnswersAerobic cellular respiration- C6H12O6+ 6O2- 6CO2+ 6H2O + energy (including ATP) alcohol fermentation- C6H12O6- 2C2H5OH + 2CO2+ energy Differentiate among monosaccharides, disaccharides and polysaccharides. - Correct Answersmonosaccharides: are metabolic fuels. any of the class of sugars (e.g., glucose) used for energy disaccharides: two monosaccharide residues. polysaccharides: consist of a number of sugar molecules bonded together. How does photosynthesis impact pH? - Correct Answersphotosynthesis in a solution consumes the CO2, when the CO2 is taken out of a solution the pH increases and the solution becomes less acidic Be able to determine sample data from algae cells exposed to light compared to those left in the dark. - Correct AnswersLight absorbance is higher than dark absorbance