New York State Chemistry RegentsNew York State Earth Science Regents

 
Laboratory Skills
Living Environment Regents Review Practice Laboratory Skills Question 11 PDF Print E-mail
Sunday, 28 June 2009 12:39

To separate leaf pigments, a biologist should use

A) Chromatography

B) Dissection

C) An electronic balance

D) A dichotomous key

Correct Answer: Option A – Chromatography

Chromatography is the collective term for a set of laboratory techniques for the separation of mixtures. It involves passing a mixture dissolved in a mobile phase through a stationary phase, which separates the analyte to be measured from other molecules in the mixture and allows it to be isolated.

Incorrect Answers:

Dissection is usually the process of disassembling and observing something to determine its internal structure and as an aid to discerning the functions and relationships of its components. 

Electronic balances are instruments used to measure the mass of items.

A dichotomous key is a method for determining the identity of something (like the name of a butterfly, a plant, lichen, or a rock) by going through a series of choices that leads the user to the correct name of the item. Dichotomous means "divided in two parts".

Hence, options B, C and D are incorrect.

Last Updated on Thursday, 02 July 2009 07:11
 
Living Environment Regents Review Practice Laboratory Skills Question 12 PDF Print E-mail
Sunday, 28 June 2009 12:38

An experimental design included references from prior experiments, materials and equipment, and step-by-step procedures. What else should be included before the experiment can be started?

A) A set of data

B) A conclusion based on data

C) Safety precautions to be used

D) An inference based on results

Correct Answer: Option C - Safety precautions to be used

In addition to the above information in the research plan safety precautions to be used form a vital part, since safety is a major concern for any experiment to be conducted in a laboratory.

A set of data, conclusion from the data and inference based on the results are the processes to be undertaken after the experiment has been conducted. Hence, options A, B and D are incorrect.

Last Updated on Thursday, 02 July 2009 07:11
 
Living Environment Regents Review Practice Laboratory Skills Question 13 PDF Print E-mail
Sunday, 28 June 2009 12:36

The current knowledge concerning cells is the result of the investigations and observations of many scientists. The work of these scientists forms a well-accepted body of knowledge about cells. This body of knowledge is an example of a

A) Hypothesis

B) Theory

C) Controlled experiment

D) Research plan

Correct Answer: Option B – Theory

A theory, in the general, is an analytical structure designed to explain a set of observations.

Incorrect Answers:

Hypothesis is premise which has to be tested by conducting a certain experiment.

A controlled experiment generally compares the results obtained from an experimental sample against a control sample, which is practically identical to the experimental sample except for the one aspect whose effect is being tested.

A research plan is a design report including all the aspects of the research experiment to be conducted, which includes the design, hypothesis, tools, techniques and safety measures.

Last Updated on Thursday, 02 July 2009 07:11
 
Living Environment Regents Review Practice Laboratory Skills Question 14 PDF Print E-mail
Sunday, 28 June 2009 12:34

A scientist tested a hypothesis that white-tailed deer would prefer apples over corn as a primary food source. The findings of the test, in which the scientist claimed that the deer preferred apples, were published. Which research technique, if used by the scientist, might result in this claim being questioned?

A) The scientist observed four deer in different locations at various times of the day.

B) The scientist observed a total of 500 deer in 20 different locations at various times of the day.

C) The scientist observed 200 deer in various natural settings, but none in captivity.

D) The scientist observed 300 deer in various locations in captivity, but none in natural settings.

Correct Answer: Option A - The scientist observed four deer in different locations at various times of the day.

Limited sample size in restricted conditions cannot provide detailed test results to conclude an experiment and test a hypothesis. For any experiment to provide an acceptable result there should be a sizable sample and the experiment conducted considering other factors affecting the hypothesis. Hence, observations of 4 Deer in different locations at various times of the day become a questionable aspect for the accuracy of the conclusion.

The options B, C and D have bigger sample sizes ranging from 200 to 500 and also the data is collected from various locations. Hence, under these conditions the conclusion of the scientist cannot be questioned.

Last Updated on Thursday, 02 July 2009 07:12
 
Living Environment Regents Review Practice Laboratory Skills Question 15 PDF Print E-mail
Sunday, 28 June 2009 12:33

Answer questions 15 and 16 based on the information provided below:

A small green plant planted in a test tube is placed in a flask sealed by a rubber stopper. One end of a sensor that measures the CO2 content of the air in the flask is inserted, through the rubber stopper and the other end of the sensor is connected to a computer to monitor and record CO2 levels in the flask over a period of 60 minutes.

Observations:

  • The CO2 level in the flask falls slowly for the first 25 minutes.
  • The CO2 level gradually starts increasing in the next 35 minutes
Which process most likely caused the change in CO2 level in the flask over the last 35 minutes?

A) Photosynthesis

B) Respiration

C) Active transport

D) Circulation

Correct Answer: Option B – Respiration

When plants respire they take in oxygen and give out carbon dioxide. This process provides energy to the plant.

Incorrect Answers:

The process of photosynthesis would lead to generation of oxygen by consumption of carbon dioxide and sunlight.

Active transport is the mediated process of moving particles across a biological membrane against a concentration gradient.

Circulation is a system which moves substances from one cell to another.

Hence, options A, C and D are incorrect.

Last Updated on Thursday, 02 July 2009 07:12
 
Living Environment Regents Review Practice Laboratory Skills Question 16 PDF Print E-mail
Sunday, 28 June 2009 12:32

Which condition most likely produced the effect on CO2 level over the first 25 minutes?

A) The light was on for the entire 25 minutes.

B) The light was off for the entire 25 minutes.

C) The light was off at the start and turned on after 10 minutes.

D) The light could have been either on or off because it would have had no effect on the CO2 level.

Correct Answer: Option A - The light was on for the entire 25 minutes.

The process of photosynthesis takes place in the presence of carbon dioxide and light leading to the generation of oxygen, hence, decreasing the amount of carbon dioxide in the flask for the first 25 minutes.

Hence, the options B, C and D are incorrect.

Last Updated on Thursday, 02 July 2009 07:14
 
Living Environment Regents Review Practice Laboratory Skills Question 17 PDF Print E-mail
Sunday, 28 June 2009 12:31

Tomato plants in a garden are not growing well. The gardener hypothesizes that the soil is too acidic. To test this hypothesis accurately, the gardener could

A) Plant seeds of a different kind of plant

B) Move the tomato plants to an area with less sunlight

C) Change the pH level of the soil

D) Reduce the amount of water available to the plant

Correct Answer: Option C - Change the pH level of the soil

Acidic or alkaline nature of the soil is measured by the pH level. Hence, if the gardner has to test his hypothesis that the plants were not growing well due to the soil being acidic, he has to change the pH level of the soil and observe if there are changes in the growth of the tomato plants.

All the other options provide tests not adequate for the hypothesis of the gardner. Hence, they are incorrect.

Last Updated on Thursday, 02 July 2009 07:14
 
Living Environment Regents Review Practice Laboratory Skills Question 18 PDF Print E-mail
Sunday, 28 June 2009 12:29

A glucose-tolerance test was conducted to observe the effect of time on glucose concentration in the blood. An animal was fed A0 milliliters of glucose solution. At five different times after the ingestion of the solution, the blood glucose concentration was determined, and the results were recorded in the data table below.

Time After Glucose Ingestion (minutes)

Glucose concentration in Blood (mg/A00dL)

0

75

30

125

60

110

90

90

120

80

180

70

The change in glucose concentration in the blood between 0 and 30 minutes was probably due to

A) The liver releasing glucose into the small intestine

B) Glucose being absorbed from the digestive system

C) The synthesis of glucose from starch

D) Glucose being used for cellular respiration

Correct Answer: Option B - Glucose being absorbed from the digestive system

When, the animal is fed with glucose solution, the level of glucose in the body increases from 75mg to 125 mg. After 10 minutes the process of digestion begins and this glucose is absorbed by the digestive system.

Incorrect Answers:

Liver does not produce or release glucose.

Animals do not synthesize starch from glucose since, starch is a complex sugar.

Within 10 minutes of consumption glucose does not reach the cells and cannot be used for cellular respiration. Hence, options A, C and D are incorrect.

Last Updated on Thursday, 02 July 2009 07:15
 
Living Environment Regents Review Practice Laboratory Skills Question 19 PDF Print E-mail
Sunday, 28 June 2009 12:28

In an investigation to determine the change in heart rate with increased activity, a biology teacher asked students to take their pulses immediately before and immediately after exercising for B minutes. The data showed an average heart rate of 72 beats per minute before exercising and 90 beats per minute after exercising. If a valid conclusion is to be made from the results of this investigation, which assumption must be made?

A) In most students, the average heart rate is not affected by exercise.

B) Exercise causes the heart rate to slow down.

C) Each student exercised with the same intensity.

D) The heart rate of each student goes up 18 beats after jogging for 2 minutes.

Correct Answer: Option C - Each student exercised with the same intensity.

Option A is incorrect because the heart rate changes from 72 beats to 90 beats, according to the given information.

The average heart rate after the exercise for 2 minutes is 90 as against 72 before the exercise. Hence, average heart rate increases with exercise and so, option B is incorrect.

The average heart rate after exercising for 2 minutes is 90 beats, which does not lead to a conclusion that each student’s heart rate goes up by 18 beats. Hence, option D is incorrect.

Hence, the conclusion that can be drawn from the above observations is that each student exercised with the same intensity.

Last Updated on Thursday, 02 July 2009 07:15
 
Living Environment Regents Review Practice Laboratory Skills Question 20 PDF Print E-mail
Sunday, 28 June 2009 12:26

Answer questions 20 and 21 based on the information provided below:

A student completed a series of experiments and found that a protein digesting enzyme (intestinal protease) functions best when the pH is 8.0 and the temperature is 37°C. During an experiment, the student used some of the procedures listed below:

Procedures:

(A) Adding more protease

(B) Adding more protein

(C) Decreasing the pH to 6.0

(D) Increasing the temperature to 45°C

(E) Decreasing the amount of lightWhich two procedures would most likely cause a decrease in the rate of protein digestion?

A) A and D

B) B and C

C) A and E

D) C and D

Correct Answer: Option D – C and D

The decrease in pH to 6 and increase in temperature to 45°C would cause the decrease in the rate of protein digestion.

Amount of light, additional protein or protease will not lead to a decrease in the rate of protein digestion.

Last Updated on Thursday, 02 July 2009 07:15
 
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