# diffusion/osmosis lab

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Diffusion/Osmosis Lab. Which beaker(s) contain(s) a solution that is hypertonic to the bag?. Beaker 3 Beaker 2 and 4 Beaker 1, 2, and 5 Beaker 4 Beakers 3 and 4. Which beaker(s) contain(s) a solution that is hypertonic to the bag?. C. Beaker 1, 2, and 5. - PowerPoint PPT Presentation

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• Diffusion/Osmosis Lab

• Which beaker(s) contain(s) a solution that is hypertonic to the bag?Beaker 3Beaker 2 and 4Beaker 1, 2, and 5Beaker 4Beakers 3 and 4

• Which beaker(s) contain(s) a solution that is hypertonic to the bag?C. Beaker 1, 2, and 5The correct answer is C. Hypertonic means that the solute concentration in the beaker is higher than in the bag. This is true for beakers 1, 2, and 5. Beaker 3 is isotonic to the bag, and beaker 4 is hypotonic to the bag.

• 2. Which bag would you predict to show the least change in mass at the end of the experiment?

The bag in Beaker 1The bag in Beaker 2The bag in Beaker 3The bag in Beaker 4The bag in Beaker 5

• 2. Which bag would you predict to show the least change in mass at the end of the experiment?

C. The bag in Beaker 3The correct answer is C. Since the two solutions shown are isotonic, there will be no net gain or loss of water, and therefore a negligible change in mass.

• 3. In beaker B, what is the water potential of the distilled water in the beaker, and of the beet core?

Beaker = 0, Beet core = 0Beaker = 0, Beet core = -0.2Beaker = 0, Beet core = 0.2Beaker cannot be calculated, Beet core = 0.2Beaker cannot be calculated, Beet core = -0.2

• 3. In beaker B, what is the water potential of the distilled water in the beaker, and of the beet core?

B. Beaker = 0, Beet core = -0.2The correct answer is B. Since water potential = solute potential (-0.4) + pressure potential (0.2), water potential = -0.2

• 4. Which of the following statements is true for the diagrams?

The beet core in A is at equilibrium with the waterThe beet core in B will lose water to its environmentThe beet core in B will be more turgid than beet core ABeet core A will gain so much water it will likely ruptureThe cells in beet core B will likely undergo plasmolysis

• 4. Which of the following statements is true for the diagrams?

The beet core in A is at equilibrium with the waterThe correct answer is A. Both the distilled water and the beet core have a water potential of 0.

• Enzyme Lab

• 1. During what time interval is the enzyme working at its maximum velocity?

0-30 seconds60-120 seconds120-180 secondsOver the entire time course

• 1. During what time interval is the enzyme working at its maximum velocity?

0-30 secondsThe correct answer is A. During this time interval, the amount of substrate is at its max., so an enzyme molecule encounters another substrate molecule as soon as it releases product. After the initial period, the rate drops. During the time interval from 300 to 360 seconds, the rate of reaction is zero; all the substrate has been consumed.

• 2. In order to keep the rate constant over the entire time course, which of the following should be done?

• 2. In order to keep the rate constant over the entire time course, which of the following should be done?

C. Add more substrateThe rate of the reaction drops when the enzyme no longer has a maximum number of substrate molecules to interact with. Above the maximum substrate concentration, the rate will not be increased by adding more substrate; the enzyme is already working as fast as it can. An enzyme can catalyze a certain number of reactions per second, and if there is not sufficient substrate present for it to work at its maximum velocity, the rate will decrease. Therefore, to keep the enzyme working at its maximum, you must add more substrate

• 3. What role does a strong acid play when added to a reaction that requires enzymes?

It is the substrate on which the enzyme actsIt binds with the remaining productIt accelerates the reaction between the enzyme and the substrateIt blocks the active site of the substrateIt denatures the enzyme by blocking the active site

• 3. What role does a strong acid play when added to a reaction that requires enzymes?

E. It denatures the enzyme by blocking the active site

The correct answer is E. Strong acids lower the pH so that the globular shape of the protein is altered. The active site is distorted to the point that the enzyme no longer functions.

• Mitosis and Meiosis

• 1. Name the phases of mitosis shown below.

• 1. Name the phases of mitosis shown below.Metaphase Telophase Anaphase

• 2. Suppose that an onion root cell spends 24 hours in the cell cycle, and 75% of its time in Interphase. A. How long does it spend in Interphase, andB. Why does it spend 75% of its time in Interphase?

• 2. Suppose that an onion root cell spends 24 hours in the cell cycle, and 75% of its time in Interphase. A. How long does it spend in Interphase, and3 x 24 = 18 hrs.4

B. Why does it spend 75% of its time in Interphase?G1 (growth), S (DNA replication), G2 (prep. for mitosis)Also must go through checkpoints to ensure proper size and function

• 3. Which of the following statements is correct?Crossing over occurs in prophase I of meiosis and metaphase of mitosisDNA replication occurs once prior to mitosis and twice prior to meiosisBoth mitosis and meiosis result in daughter cells identical to the parent cellsKaryokinesis occurs once in mitosis and twice in meiosisSynapsis occurs in prophase of mitosis

• 3. Which of the following statements is correct?D. Karyokinesis occurs once in mitosis and twice in meiosisThe correct response is D. There are two nuclear divisions in meiosis, and only one in mitosis. Crossing over occurs only in meiosis; it does not occur at all in mitosis. Replication occurs only once in preparation for both mitosis and meiosis. The daughter cells of mitosis are identical to the parent cell, but in meiosis the daughter cells have only one of each homologous chromosome pair. Synapsis occurs only in prophase I of meiosis.

• 4. Use the figure below to answer the question. For an organism with a diploid number of 6, how are the chromosomes arranged during metaphase I of meiosis?

• 4. Use the figure below to answer the question. For an organism with a diploid number of 6, how are the chromosomes arranged during metaphase I of meiosis?The correct answer is C. Homologous pairs line up during metaphase I of meiosis.

• 5. A group of asci formed from crossing light-spored Sordaria with dark-spored produced the following results:How many of these asci contain a spore arrangement that resulted from crossing over? A. 3B. 7C. 8D. 10E. 15

Number of Asci CountedSpore Arrangement74 light/4 dark spores84 dark/4 light spores32 light/2 dark/2 light/2 dark spores42 dark/2 light/2 dark/2 light spores12 dark/4 light/2 dark spores22 light/4 dark/2 light spores

• 5. A group of asci formed from crossing light-spored Sordaria with dark-spored produced the following results:How many of these asci contain a spore arrangement that resulted from crossing over? D. 10Remember that if crossing over does not occur, the arrangement of spores will be 4 light and 4 dark. All other combinations are the result of crossing over.

Number of Asci CountedSpore Arrangement74 light/4 dark spores84 dark/4 light spores32 light/2 dark/2 light/2 dark spores42 dark/2 light/2 dark/2 light spores12 dark/4 light/2 dark spores22 light/4 dark/2 light spores

• Photosynthesis

• 1. What is the Rf value for carotene calculated from the chromatogram below?

1.090.170.960.330.50

• 1. What is the Rf value for carotene calculated from the chromatogram below?

C. 0.96

Rf = distance pigment migrates/ distance solvent front migrates, = 11.5/12, = 0.96.

• 2. Choose the terms that will best complete the statement below:In the light reactions of photosynthesis, light energy excites electrons in plant pigments such as________, and boosts them to a higher energy level. These high-energy electrons reduce compounds (______________) in the _________membrane, and the energy is eventually captured in the chemical bonds of ___________.A. chlorophyll, electron acceptors, thylakoid, NADH/ATPB. chlorophyll, electron acceptors, thylakoid, NADPH/ATPC. carotene, electron acceptors, thylakoid, NADPH/ATPD. chlorophyll, electron donors, chloroplast, FADH2E. chlorophyll, electron donors, chloroplast, ATP

• 2. Choose the terms that will best complete the statement below:In the light reactions of photosynthesis, light energy excites electrons in plant pigments such as________, and boosts them to a higher energy level. These high-energy electrons reduce compounds (______________) in the _________membrane, and the energy is eventually captured in the chemical bonds of ___________.C. carotene, electron acceptors, thylakoid, NADPH/ATP