New York State Chemistry RegentsNew York State Earth Science Regents

 
Laboratory Skills: Scientific Inquiry & Technique
Living Environment Regents August 2010 Question 32 PDF Print E-mail
Friday, 27 May 2011 13:55
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Correct answer: (2) make cell structures more visible

Stains are used to help microscope viewers see the different structures of a specimen. Iodine is an example of a stain commonly used in laboratories. Iodine is used as a starch indicator, making structures with starch dark blue in color.

Incorrect answers:

(1) eliminate some organelles

An organelle is one of the several formed bodies with a specific role and suspended in the cytoplasm of eukaryotic cells. Stains are not applied to destroy these organelles because when this happens, the cell viewed on the microscope would be destroyed.

(3) use the high-power lens

No staining agent is needed to use the high-power lens. Just move the nosepiece to move the lens from one objective to another.

(4) remove water from the slide

If water is removed from the wet-mount, the cell will dry up and the cell shown on the microscope will be disrupted.
 
Living Environment Regents August 2010 Question 51 PDF Print E-mail
Friday, 27 May 2011 16:31
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Correct answer: 15 mm

The smallest calibration of the ruler is 1mm, which is represented by the smaller vertical lines in the ruler. For every 10 millimeters, there is one centimeter, represented by the longer vertical lines accompanied by numbers. Since the anterior part of the larva is not located at zero, we must take note of where the anterior and posterior most part of the larva land on the ruler. As shown in the diagram, it is located at 1cm and 2.5cm. Therefore, deduct the ending point with the starting point to get its length. The answer is 1.5cm. To convert it to millimeters, multiply 1.5cm with 10mm. Thus, the length of the larva in millimeters is 15mm.

Last Updated on Friday, 27 May 2011 16:55
 
Living Environment Regents August 2010 Question 52 PDF Print E-mail
Friday, 27 May 2011 16:56
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Living Environment Regents August 2010 Question 53 PDF Print E-mail
Friday, 27 May 2011 17:04
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Last Updated on Friday, 27 May 2011 17:11
 
Living Environment Regents August 2010 Question 54 PDF Print E-mail
Friday, 27 May 2011 17:31
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Living Environment Regents August 2010 Question 67 PDF Print E-mail
Friday, 27 May 2011 18:11
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Correct answer: (1) paper chromatography

Paper chromatography is a laboratory technique used to separate substances with different rates of migration across a sheet of paper. The paper is initially placed in a particular solvent to create a stationary liquid phase. Then the test solution is dropped near the edge of the paper (indicated in the illustration as the original spot). Then the tip is dipped in another solvent to allow the movement of the components of the test solution based on the sizes of the molecules and their solubility in the solvent.

Incorrect answers:

(2) gene manipulation

Gene manipulation, also known as genetic engineering, is a process that involves the use of various laboratory tools and enzymes to cut out, insert, and alter pieces of the DNA that contain one of more genes of interest.

(3) dissection

Dissection is a process usually used in anatomy, wherein the external parts are disassembled, by cutting or slicing, to analyze the structure and function of the internal body parts of an organism.

(4) staining

Staining refers to the laboratory technique that uses stains or dyes to adjust the contrast of samples to be viewed through laboratory equipment, such as the microscope. This can be used for better viewing of the various parts and components of the samples under the microscope. It can also be used to determine if a specific type of molecule is present in a sample. For example, iodine is used to determine the presence of starch in a sample, indicated by the dark blue coloration.
 
Living Environment Regents August 2010 Question 68 PDF Print E-mail
Friday, 27 May 2011 18:13
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Correct answer: (3) control group

In the experiment, all the participants listened to music. The researcher should have added another group to serve as the control. The control group will not listen to the different types of music, but their pulse rates will be recorded every 30 seconds. If the pulse rates of the control group and the experimental group (persons that listened to the music) are different, then the conclusion is valid.

Incorrect answers:

(1) prediction

The prediction is the specific ways of how to test whether a hypothesis is true. In the given scenario, the prediction is indicated in this sentence: She thought that pulse rate would change with different types of music.

(2) hypothesis

The hypothesis is the trial answer to a stated problem based on pertinent facts found in previous studies. It might not be indicated that she did research about previous studies, but it is very likely that she came up with the hypothesis that listening to different types of music would affect pulse rate after doing some observations or research.

(4) research plan

The researcher has a research plan, which is indicated in this sentence: Each person participating in her experiment listened to seven different selections of music for 30 seconds each. The pulse rates were taken after each 30-second interval of music.
 
Living Environment Regents August 2010 Question 69 PDF Print E-mail
Friday, 27 May 2011 18:15
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Correct answer: (3) pulse rate of each group

The dependent variable refers to the variable that is influenced by the changes in the independent variable. In this experiment, the independent variable is the soda. The researcher is testing the effect of the absence or presence of caffeine on pulse rate.

Incorrect answers:

(1) type of soda given to each group

The type of soda is the independent variable because it is not affected by the other variable, which is the pulse rate.

(2) amount of soda given to each group

The amount of soda is constant among the groups; thus, it is not the dependent variable.

(4) age of participants in each group

The age of the group does not change with the manipulation of the independent variable.
 
Living Environment Regents August 2010 Question 70 PDF Print E-mail
Friday, 27 May 2011 18:17
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The researcher should have measured the number of times the second group could squeeze the clothespin prior to the exercise so that he could compare it with the number of squeezes after the exercise. On the other hand, the first group should also do two one-minute takes of squeezing. The results of the first trial of each group must be compared with the second trial. If the results of the first and second trials of the first group are the same, then the hypothesis could be false. If the results of the first and second trials of the second group are different, then the hypothesis could be true.
 
Living Environment Regents August 2010 Question 73 PDF Print E-mail
Friday, 27 May 2011 18:31
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The artificial cell has a semi-permeable membrane, thus the glucose and the starch molecules could move out of the artificial cell by diffusion. Diffusion is the spontaneous tendency of a substance to move down its concentration gradient from a more concentrated to a less concentrated area. When the starch molecules reach the solution outside the artificial cell, then the starch indicator would react with the starch molecules and will turn the solution into a dark blue color.
 
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