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BIOL 103 II Year 2024 Exam with
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After light passes through the specimen, it next enters this lens system - Correct Ans: ✔✔Iris diaphragm--Increases or decreases the light intensity Stage--Platform that supports a microscope slide Condenser--Concentrates light onto the specimen Adjustment knob--Causes stage (or objective lens) to move upward or downward Objective lens system--After light passes through the specimen, it next enters this lens system A change in what component of microscopy influences the apparent size of the objects being viewed? - Correct Ans: ✔✔Magnification What is the advantage of using a wet mount? - Correct Ans: ✔✔- The motility of a specimen can be viewed under a microscope.
- The specimen can be viewed as living cells. Indicate the correct order of steps as you bring an object into focus under high power. - Correct Ans: ✔✔1) Place slide on stage and secure with stage clips.
- Turn on the light and center the specimen over the light source.
- Focus specimen on scanning objective using coarse focus adjustment
- Rotate to low power objective, then use fine focus to sharpen the image
- Rotate high power lens into position.
- Readjust fine focus under high power to produce the sharpest image. Negative Control - Correct Ans: ✔✔Any procedure that is known to NOT produce the desired result. A negative test result means what you are looking for is NOT present. Positive Control - Correct Ans: ✔✔Any procedure that is known to produce the desired result. A positive test result means what you are looking for is present. The Benedict Test - Correct Ans: ✔✔detects the presences of simple sugars or monosaccharides; the Benedict solution turns from blue to red in the presence of increasing amounts of sugar The Biuret Test - Correct Ans: ✔✔detects the presence and concentration of protein; the Biuret solution starts blue without protein and turns purple when protein is present There are four different types of macromolecules: - Correct Ans: ✔✔1. Carbohydrates (Sugars)
When Benedict reagent is added to a solution containing simple sugars, the solution turns green, orange, or red. In the absence of simple sugars, the solution is blue. Benedict reagent was added to solutions that may or may not contain simple sugars. The color change that occurs is considered the ______________________________________.
- Correct Ans: ✔✔dependent variable The Benedict's test indicates a positive result when the solution turns...
- Correct Ans: ✔✔red, green, orange, yellow Kathy wants to cut sugar out of her diet. She realizes that she consumes more simple sugars in her beverages than she realized. Predict the amount of simple sugar in each of these beverages by indicating the color change you would expect to occur with the Benedict's solution. Explain your observations. Diet iced tea, Milk, Orange juice, Coffee with one sugar. - Correct Ans: ✔✔The Benedict test detects simple sugars or monosaccharides via changes in color to the solution. Blue represents no simple sugars. The color then progresses through green/yellow, orange, and red as simple sugar content increases. Diet iced tea contains 0g sugar, so the Benedict solution's color should stay blue. Milk has approximately 12g sugar; orange juice, particularly Tropicana orange juice, has about 22g sugar; and coffee, supposing black coffee with one tsp sugar, has an anticipated 4g sugar. Accordingly, the coffee should yield a green/yellow color; the milk should turn the Benedict's solution orange; and the Tropicana orange juice should change the solution to red.
Diet iced tea - blue. There is no sugar added, only artificial sweaters which are not sugars. Milk - orange. Milk sugar is lactose. Orange juice - red. Fruits have a lot of natural sugars which accounts for their sweet flavors. Coffee with one sugar - green/yellow. Coffee alone doesn't have sugar but you are adding sugar. Which reagent is used to detect the presence of starch? - Correct Ans: ✔✔iodine Polysaccharides are polymers composed of - Correct Ans: ✔✔sugars. Which color change represents a positive reaction for the presence of starch using the iodine test? - Correct Ans: ✔✔Color change from amber to blue/black T/F The formation of an orange or purple color after the addition of iodine indicates that a sample contains lipids. - Correct Ans: ✔✔False-- Iodine is not used to detect the presence of lipids. When testing for starch within the potato and onion, the test tube containing potato turned purple while the test tube containing onion turned orange. What can you conclude about the amount of starch in these two vegetables? - Correct Ans: ✔✔The potato contained a higher concentration of starch than the onion.
Ans: ✔✔Unlike his/her two acquaintances, the suspect ordered some chips. Chips contain fats or lipids, particularly oil. So, an oily spot should appear on the suspect's paper napkin, as a lipid (chips) that has been in contact with paper will result in an evenly distributed oily stain materializing on the paper after 15 minutes. The potato chips would leave grease stains on the napkins from the oil used to fry them. Predict the lipid content of the following food items by ranking them in order from least to most lipid content. Explain your ranking by indicating the potential results from the lipid test performed here. Donut, piece of white bread, saltine cracker, bagel. - Correct Ans: ✔✔All the food items contain at least some fat; however, saltine crackers, white bread, and bagels have a comparatively low lipid/fat content donuts. White bread seemingly has the least fat, followed by the saltine cracker, and then the bagel. On the other end, donuts-- doused in shortening--can be seen as a highly fatty food. Appropriately, a lipid test on a white bread piece, a saltine cracker, and a bagel would presumably yield only a faint stain on the paper--faintest on the bread, a little less faint on the saltine cracker as compared to the bread, and a bit more visible on the dense bagel---while a lipid test on the fatty donut would yield a greasy stain. Which of the following are functions of proteins? - Correct Ans: ✔✔- Catalytic (enzymatic) activity
- Transport of molecules/ions through blood and across plasma membranes Proteins are polymers composed of - Correct Ans: ✔✔amino acids. Which color change represents a positive reaction for the presence of protein using the Biuret test? - Correct Ans: ✔✔Color change from blue to purple When biuret reagent is added to a solution containing protein, the solution turns pink or purple. In the absence of protein, the solution is blue. Biuret reagent was added to solutions that may or may not contain protein. What is the dependent variable in this experiment? - Correct Ans: ✔✔The color change from blue to purple A negative control is a sample that you know will give you a negative result. You are testing for the presence of proteins, simple sugars, starch, and lipids in various foods. What would be the best negative control for this experiment? - Correct Ans: ✔✔Distilled water, because it does not contain any of the molecules you are testing for. What may affect the rate of an enzyme-driven reaction? - Correct Ans: ✔✔- pH
- Temperature
- Concentration of enzyme
- have a special shape that controls their function.
- control the speed of reactions. Enzyme function is optimum - Correct Ans: ✔✔at specific pH and temperature ranges. When testing the temperature of catalase in the enzyme lab, why did the higher temperature affect the catalase activity? - Correct Ans: ✔✔Some of the catalase enzymes were denatured. A small amount of lipase, called gastric lipase, is made by cells in your stomach. The average temperature of the stomach is 37oC(98.6oF). This enzyme specifically digests butterfat in your food. Lipase is an enzyme that breaks down dietary fats into smaller molecules called fatty acids and glycerol. This enzyme was extracted by Jane and added to butter (a fatty food), then left on ice for thirty minutes. The reaction did not occur. What property of enzymes explains why the reaction did not occur? Also was this a catabolic or anabolic reaction? Explain. - Correct Ans: ✔✔Gastric lipase operates/reacts in temperatures at or near 37 degrees Celsius--the average temperature seen in the stomach where the enzyme originates--and potentially reacts even faster at higher temperatures up to a certain point. So, exposing the enzyme to lower, colder temperatures via leaving butter-added enzyme on ice for thirty minutes will not yield a reaction. As lipase breaks down dietary fat into smaller molecules called fatty acids and glycerol, this reaction can be seen as a catabolic reaction. (Catabolism breaks down complex molecules into simpler ones).
The reaction did not occur because enzymes are sensitive to environmental conditions. In this case, the temperature was too cold. This enzyme needs a temperature around that of human body temperature to function optimally. This is a catabolic reaction because better fat is broken down into fatty acids and glycerol. Complete the calculations for total magnification produced by various combinations of the eyepiece and objective lenses. Remember, to calculate the total magnification achieved when using a particular objective, multiply the power of the eyepiece by the power of the objective used. - Correct Ans: ✔✔- When the scanning (4x) objective is used the total magnification will be 40x.
- When the low power (10x) objective is used the total magnification will be 100x.
- When the high power (40x) objective is used the total magnification will be 400x.
- When the oil immersion (100x) objective is used the total magnification will be 1000x. In the calculations above, what was the power of the eyepiece lens? - Correct Ans: ✔✔10x Match the names of the microscope parts in column A with the descriptions in column B. Place the letter of your choice in the space provided.
- Observe preparation under the 40X objective lens. Match the names of the microscope parts in column A with the descriptions in column B. Place the letter of your choice in the space provided. 1 Nosepiece 2 Arm 3 Stage (slide) clip 4 Eyepiece (ocular) 5 Field of view Holds a microscope slide in position Contains a lens at the top of the body tube Serves as a handle for carrying the microscope Part to which the objective lenses are attached Circular area seen through the eyepiece - Correct Ans: ✔✔Stage clip-- Holds a microscope slide in position Eyepiece--Contains a lens at the top of the body tube Arm--Serves as a handle for carrying the microscope Nosepiece--Part to which the objective lenses are attached Field of view--Circular area seen through the eyepiece
The structure that easily distinguishes a plant cell from an animal cell is
- Correct Ans: ✔✔chloroplasts. What type of organism is Elodea? - Correct Ans: ✔✔Plant When viewing Elodea under a microscope, what is the most likely identity of green, round structures inside of the cell? - Correct Ans: ✔✔chloroplasts A student is designing an experiment about cell size in organisms of different sizes. Her hypothesis is that larger organisms will have larger cells. She collects cheek cells from five different students in her class and estimates their size under the microscope. - Correct Ans: ✔✔height of human students Transcription - Correct Ans: ✔✔The process of copying the DNA so that the information can leave the nucleus Translation - Correct Ans: ✔✔The copy of the gene made via transcription can direct the formation of a sequence of amino acids which creates the protein. This process occurs in the ribosome. Codons - Correct Ans: ✔✔Three nucleotides that each stand for one specific amino acid
Rank the following steps in the correct order that you would use to isolate DNA from strawberries. Wait for DNA precipitate to form Add ice cold ethanol to test tube Dissolve meat tenderizer and add it to test tube Transfer strawberry filtrate to test tube Spool DNA precipitate onto glass rod - Correct Ans: ✔✔1) Transfer strawberry filtrate to test tube.
- Dissolve meat tenderizer and add it to test tube.
- Add ice cold ethanol to test tube.
- Wait for DNA precipitate to form.
- Spool DNA precipitate onto glass rod. DNA is used as a template for making - Correct Ans: ✔✔proteins and RNA. The sequence of __________ in nucleic acids encodes a specific order of amino acids for making a protein. - Correct Ans: ✔✔nucleotides A group of three nucleotides acts as a "code word" or template for making - Correct Ans: ✔✔one amino acid.
Using the correct base pairing rules for DNA replication, what would be the complementary strand for the strand TACCGATGC? - Correct Ans: ✔✔ATGGCTACG In DNA replication, _______________________ pairs with thymine, and cytosine pairs with _______________________. - Correct Ans: ✔✔adenine; guanine In translation, what would be the correct tRNA anticodon for the codon ACC? - Correct Ans: ✔✔UGG If we extracted DNA from a strawberry as described and repeated the same procedure on a steak, would the DNA look different? Why or why not? What about the DNA makes the strawberry and steak (i.e. cow muscle) different? - Correct Ans: ✔✔DNA is universal. Thus if we repeated this procedure on any living organism, the extracted DNA would look exactly the same. The different genetic code that distinguishes organisms, tissues, cells, etc. is the order of nitrogen bases. During translation, adenine in mRNA pairs with ________________________ in tRNA, and guanine pairs with ________________________. - Correct Ans: ✔✔uracil; cytosine Match the inoculated agar plates with their growth after incubation.
every cell in the organism. Correspondingly, bacteria exist as unicellular organisms, so genetically-engineering a bacterium into a transgenic organism will involve implanting the new gene into a mere one cell whereas, for multicellular organisms such as a fish, the new gene will have to be inserted into all its numerous cells. Genetic engineering the multi-celled animal can best be achieved within the zygote life stage. As a zygote, the animal would be a single-celled organism. (a) Fish are multicellular and bacteria are single-celled. (b) It would be easiest to manipulate multicellular organisms at conception when they are a single-fertilized egg or a few-celled blastula/embryo. Scientists often want to know if the transgenic organism can pass its new traits on to its offspring and future generations. Considering life history traits (i.e. birth rates, death rates, life span, etc.), which would be a better candidate to get this information: bacteria or fish? Why? - Correct Ans: ✔✔Bacteria can see to transformation, a natural process that can be utilized in the laboratory to insert medicinally utile genes into bacterial cells that then yield a particular protein, like insulin or human growth hormone. Correspondingly, transformation can be utilized in genetic engineering wherein plasmids, circular DNA inherently seen in some bacteria, can be engineered to carry genes via one organism into a bacterial cell. Addedly, bacteria reproduce asexually, by simple division, to reproduce copiously and in no time, allowing them to be more appropriate experimental testees for investigating whether the transgenic organism can pass its new traits on to its offspring and future generations. As bacteria exist as single-
celled organisms, developing transgenic bacteria, as seen in this experiment, can be comparatively easy, but to create a transgenic animal, like fish, multi-celled organisms whose numerous cells the new gene would have to be inserted into, would, for sure, prove a challenge for scientists and experimenters. Bacteria reproduce and mature much more rapidly. If you were to shine the UV light on the pGLO/bla DNA solution, you would not see any color. The DNA solution itself is clear. Describe why the plates glow while the DNA itself if colorless. Use the terms transcription and translation in your answer. - Correct Ans: ✔✔The plates glow whilst the DNA remains colorless for the reason that pGLO plasmid DNA, on its own, will not illuminate in reaction to ultraviolet light exposure. Rather, a protein, the green fluorescent protein gene, that the new DNA creates within the cells via transcription (RNA polymerase catalyzes mRNA synthesis using the gene's DNA) and translation (within ribosomes, a codon--a trinucleotide mRNA sequence that corresponds to a particular amino acid--will be matched with a tRNA anticodon to synthesize the protein) seems to yield luminescent/light-emitting properties in the bacterial colonies. This fluorescence epitomizes as a gene, and proteins express genes. The DNA must be transcribed and translated into a protein. It is the protein and not the DNA that glows.
