LAB Week1-3

Which is a good hypothesis for this tadpole experiment?

Tadpoles will be larger if fed a meat-based diet.

Compare pure water and coffee. Their pH differs by approximately____Correct pH units, which means that water has ______Correcttimes _______ Correct hydrogen ions than coffee.

2, 100, fewer 3, 1000, more

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

40x 100x 400x 1000x

Using the interactive calculator, determine the hydrogen ion concentrations that correspond to each pH value and enter them into the table. Include one digit past the decimal. Then complete the final sentence with a pH value

6.3,7.9,2.0 highest7.7

What is the advantage of using a wet mount?

The motility of a specimen can be viewed under a microscope The specimen can be viewed as living cells

What is the advantage of using a wet mount?

The motility of a specimen can be viewed under a microscope, The specimen can be viewed as living cells.

dentify the correct statements about lab coats.

Lab coats provide some protection against contamination with infectious microorganisms. Lab coats provide some protection against exposure to corrosive chemicals.

Which of the following is NOT a commonly used unit of length in the metric system

electrometer

Which of the following should be worn at ALL times in the lab?

lab coat closed-toed shoes

In which circumstance is food and/or beverage allowed in the laboratory?

never

The meniscus is

curvature of the water level.

Assume you drink 250mL of soda out of a 1 liter soda bottle. How many liters are left

0.75 liters

Indicate the correct order of steps as you bring an object into focus under high power

1. Place slide on stage and secure with stage clips. 2. Turn on the light and center the specimen over the light source. 3. Focus specimen on scanning objective using coarse focus adjustment 4. Rotate to low power objective, then use fine focus to sharpen the image 5. Rotate high power lens into position. 6. Readjust fine focus under high power to produce the sharpest image

Algal phytoplankton are single-celled aquatic organisms that perform photosynthesis like plants. In a lake, summer growth of phytoplankton can change the water pH from pH 7.2 to 6.2. Select all of the following that are TRUE about this change.Check All That Apply

1. The water at pH 6.2 is a stronger acid solution than before the phytoplankton growth. 2. The growth of phytoplankton changed the pH of the water. 4. The water at pH 6.2 has 10 times the hydrogen (H+) concentration as before the phytoplankton growth.

Arrange the following steps of applying immersion oil in the correct sequence

1.Focus on the specimen using the 40x objective lens. 2.Turn the objectives to half way between the 40x lens and the 100x lens. 3.Apply a drop of immersion oil directly onto area of the slide you were viewing. 4.Rotate the 100x lens over the microscope slide, and use the fine focus adjustment knob to sharpen the image.

If you continued to add a large quantity of strong acid to a buffer solution, what would happen?

Eventually the conjugate base would be depleted, and the pH would drop.

All buffers maintain pH at around 7.0

False

If the hypothesis in a scientific experiment is not supported, the experiment is considered a complete failure and must be repeated until a satisfactory outcome is reached.

False

Proper hand washing will sterilize the hands.

False

You may eat a snack in lab as long as there are no bacterial cultures on your bench and you have thoroughly washed your hands.

False

Blood is closely maintained at a pH of 7.4. A patient whose blood pH drops below 7.35 is suffering from metabolic acidosis and can go into a coma. What happens to the concentration of H+ ions in a patient with a blood pH of 6.4?

H+ concentration is increased ten fold.

Blood pH is closely maintained at a pH of 7.4. A patient whose blood pH drops below 7.35 issuffering from metabolic acidosis and can go into a coma. What happens to the concentration of H+ ions in a patient with a blood pH of 6.4?

H+ concentration is increased ten fold.

The interactive shows the pH scale from acidic to basic, and the corresponding hydrogen ion concentrations at each level. Compare that to this graph representing the same data. Which phrases accurately describe this graph?

Hydrogen ion concentrations increase as pH values decrease. The x-axis is on a logarithmic scale.

Some students consume large amounts of caffeinated drinks to help them stay alert when studying. You notice that many who engage in this practice seem to do poorly on exams. Suppose you want to investigate the relationship between caffeine consumption and exam performance. Which of the following statements would be an appropriate hypothesis

Students who consume large amounts of caffeine while studying have lower exam scores than students that consume less caffeine while studying.

What can explain the relative lack of effect of acid precipitation on the Clark Fork River

The carbonate ions from the limestone react with water to form a buffer.

The bicarbonate buffer system is important for our bloodstream. If something interferes with breathing and CO2 levels rise, then blood pH will fall. In this case, how would you expect the bicarbonate buffer to respond?

The extra H+ ions will be bound by the conjugate base HCO3− , pushing the equilibrium to the left.

How is the metric system different than the standard United States system

The metric system is based on units of 10

Algal phytoplankton are single-celled aquatic organisms that perform photosynthesis like plants. In a lake, summer growth of phytoplankton can change the water pH from pH 7.2 to 6.2. Select all of the following that are TRUE about this change.

The water at pH 6.2 is a stronger acid solution than before the phytoplankton growth. The water at pH 6.2 has 10 times the hydrogen (H+) concentration as before the phytoplankton growth. The growth of phytoplankton changed the pH of the water.

The interactive shows the pH scale from acidic to basic, and the corresponding hydrogen ion concentrations at each level. Compare that to this graph representing the same data. Which phrases accurately describe this graph?

The x-axis is on a logarithmic scale. Hydrogen ion concentrations increase as pH values decrease.

In the pH portion of the interactive, drag the slider bar until you see Sea Water in the upper right panel. One hundred years ago, ocean water had a pH of approximately 8.2, but now it is closer to 8.1 due to the absorption of carbon dioxide from the atmosphere.

To describe this situation, we can say that seawater is changing to become more [Acidic] than it was, due to an [Increase] in H+ ions, but its current pH can be described as slightly [Alkaline]

When preparing a wet mount specimen for viewing, the specimen should be covered with

a coverslip

Match the action to the appropriate phase of the scientific method rev: 03_23_

hypothesis-2 formulate a hypothesis and create a strategy experiment-4 carry out the strategy, collect measurements analysis-3 draw graphs, evaluate the hypothesis report-1 document results

Which of the following are potential hazards which you might encounter in the laboratory

infectious microorganisms open flames hot surfaces corrosive chemicals sharp tools or broken glass

The base unit of fluid volume in the metric system is the

liter.

The base unit of fluid volume in the metric system is the Multiple Choice

liter.

In the length unit exercise, what tool did you use to measure the circles?

metric ruler

Which objective lens provides the highest total magnification?

oil immersion

In the metric system, the ________ describes the relationship of each unit to the base unit.

prefix

What instrument did you use to weigh objects in the metric system lab?

scale

One gram is equal to 0.0022 pounds

true

The buffer can maintain the solution at a steady pH, because when base is added, the (Click to select) conjugate base weak acid CH3CO2H (Click to select) absorbs releases H+ ions, and when acid is added, the (Click to select) conjugate base weak acid CH3CO2− (Click to select) absorbs releases H+ ions

weak acid releases conjugate base absorb

A buffer typically consists of a ____________________________. The buffer system keeps pH constant because if the pH begins to drop to a lower value, the __________ acts to ____________. Conversely, if the pH begins to rise to a higher value, the ___________ acts to ____________

weak acid plus conjugate base conjugate baseb. . absorb H+d. weak acide. release H+