Hynd Bio 270 Lab Practical | questions plus answers | Updated!!
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Course
Bio 270
Institution
Bio 270
Hynd Bio 270 Lab Practical | questions plus answers | Updated!!
Put the six steps of the Scientific Method in order of their occurrence. ** Answ** 1)Observe
2)Question
3)Hypothesize
4)Experiment
5)Interpret results
6)Conclude
The variable over which the experimenter has control is ...
Put the six steps of the Scientific Method in order of their occurrence. ** Answ**
1)Observe
2)Question
3)Hypothesize
4)Experiment
5)Interpret results
6)Conclude
The variable over which the experimenter has control is the __________________
variable. ** Answ** independent
An experimental "control" and a "controlled" variable are the same thing. ** Answ**
false
The attraction (or repulsion) between two or more molecules in a solution is an example
of an intramolecular force. ** Answ** false
Which of the following molecules is the is the most polar?
a) water (H2O)
b) ethanol (EtOH)
c) isopropanol (PrOH)
d) potassium chloride (KCl) ** Answ** a) water (H2O)
Which of the following is the strongest intermolecular attraction? ** Answ** Ion-
dipole
Given the following bonds between atoms...
a) C - O - H
b) H - O - H
...select the correct statement below. ** Answ** The O in (a) will be less partially
negative than the O in (b).
Briefly state the hypothesis that tested in this experiment. Remember that a hypothesis
has to be specific, testable and refutable. Based on your background knowledge, create
a hypothesis which will predict the outcome of your experiment. Include in your
hypothesis a description of how intermolecular bonds explains the relationship between
the independent and dependent variables. It is a good practice to state a hypothesis in
the form of "If [condition], then [prediction]." For example, "If I break the speed limit
[condition or cause], then I am likely to be cited by the police [prediction or effect]."
Note: make the hypothesis universal, then observe how the hypothesis applies to your
specific situation. Finally, be sure NOT to reverse cause and effect (e.g. "If the police
,give me a citation, then I will break the speed limit"). ** Answ** If a solution has
relatively strong intermolecular forces, then it will have a relatively small drop diameter.
State the independent variable of the scientific method lab experiment. ** Answ**
the solutions
State the dependent variable of the scientific method lab experiment. ** Answ** drop
diameter
Of the following, which was not a controlled variable in the scientific method lab
experiment?
a) All of the above were controlled variables
b) None of the above were controlled variables
c) angle of the microscope slide
d) the height from which the solution was dropped
e) the flatness of the microscope slide ** Answ** A) all of the above
Generate a hypothesis about the migration rate of the two dyes through the agar.
Remember how to formulate a hypothesis from the Scientific Method lab. ** Answ**
If the molecular weight is greater, then the diffusion rate will be slower.
Look up the molecular weight of eosin and blue dextran. Match their molecular weights
below. ** Answ** Eosin=650 g/mol
Blue dextran=2,000,000 g/mol
Osmotic pressure is the driving force for the influx of water into the dialysis bag and, by
extension, the force that drives the sucrose solution up the tube. As the solution height
increases, the weight of the column of solution also increases, resulting in a downward
force; this is the hydrostatic pressure. What effect does the hydrostatic pressure have
on the movement of sucrose up the tube? ** Answ** As the hydrostatic pressure
increases, the speed of the solution movement up the tube decreases.
At time 0, the osmotic pressure was driving the movement of water into the bag and
forcing the sucrose solution up the capillary tube. However, as the experiment
continued, the speed of the solution rising up the tube decreased due to the increasing
hydrostatic pressure. ** Answ** If the system were left until equilibrium was reached,
eventually the hydrostatic pressure would increase in magnitude such that it was equal
in magnitude and in the opposite direction of the hydrostatic pressure; this would result
in a flatter plateau than seen in Figure 2 resulting from the cessation of movement of the
solution up the capillary tube.
π = iRT(ΔC) ** Answ** π = osmotic pressure (mm H2O)
i = number of osmotically active particles resulting from dissociation of each molecule in
solution (refer to Appendix A, page A8 in Sherwood).
R = gas constant (848 L-mm H2O/mol-degree)
T = temperature (K)
,ΔC = sucrose concentration difference of solute on the two sides of the membrane
(Cinside - Coutside)
Under ideal conditions (that is, conditions where the hydrostatic pressure is negligible,
there are no wall effects, the solution is not diluted by water influx, etc.), how high would
the fluid rise in the tube at 25° C ? Express your answer in millimeters (mm). **
Answ** 252,704 mm
The calculated value above is much larger than the height your solution actually rose
during the time allotted in the lab because ** Answ** under ideal conditions, gravity
(hydrostatic pressure) doesn't exist and therefore there is no opposing force to mitigate
the osmotic pressure and stop the solution from rising up the tube.
How high would the fluid rise in the tube under ideal conditions at 25° C if the solution in
the bag were changed to 0.5 M NaCl? Express your answer in millimeters (mm). **
Answ** 252,704 mm
In comparing the two values calculated above, these values are equal because **
Answ** by switching from 1 M sucrose to 0.5 M NaCl, the concentration of the solute
is halved but the number of osmotically active particles is doubled
The fluid in the body's capillaries has a greater concentration of protein than does the
interstitial fluid surrounding the capillaries. The capillary wall is freely permeable to
water, but impermeable to protein. In what direction will water move in this system? **
Answ** into the capillaries and out of the interstitial fluid
In the solutions that that "clear" when blood is added, the red blood cells are **
Answ** hemolyzing because the cells are in placed in a hypotonic solution. That is,
water is/are permeating the cell membranes and increasing the intracellular volume until
the cells burst . This destruction of the cells' membranes allows light to pass straight
through the solution without being refracted.
The discrepancy in the molar concentrations in the previous two questions is explained
by NaCl's dissociation in water. Because of this principle, there are ** Answ** 2x the
number of osmotically active particles in solution as glucose for a given molar
concentration. This increases the tonicity of the NaCl solutions, preventing water from
entering the cells and lysing the cells at lower molar concentrations.
Based on your answers and knowledge from the previous questions, what would you
expect the isotonic concentration of iron(III) chloride (FeCl3) to be? ** Answ** 0.08
M
In this lab, metabolic rate is measured indirectly using ** Answ** oxygen
consumption
, A MetaCheck machine is an instrument used to ** Answ** measure human oxygen
consumption
A nomogram is used to determine ** Answ** human surface area
Soda lime is placed in the mouse metabolism chamber to ** Answ** absorb carbon
dioxide
In terms of the relationship between body size (weight) and oxygen consumption, body
weight increases, O2 consumption increases . ** Answ** True
In terms of the relationship between of body size (weight) and metabolic rate, as body
weight increases, metabolic rate decreases. ** Answ** True
Given your answers from the previous question, humans should have a higher resting
metabolic rate than mice because they have ** Answ** humans should not have a
higher resting metabolic rate than mice
Now, perform a t-test to determine whether resting metabolic rate in mice is significantly
greater than humans. Will you use a paired or unpaired t-test ** Answ** Unpaired
Will your t-test to determine whether resting metabolic rate in mice is significantly
greater than humans be 1-tailed or 2-tailed? ** Answ** 1-tailed
A large bucket of water and a small glass of water are each brought to a boil in a cold
room. The small glass will cool faster due to its larger surface area to volume (SA:V)
ratio. Its relatively large surface area compared to the volume facilitates convective heat
loss ; the bucket loses heat slower due to its relatively small surface area compared to
the volume. ** Answ** Mice have a larger SA:V ratio than humans and therefore
lose heat faster than humans. Since mice are endothermic (warm blooded; capable of
internal generation of body heat), they must generate more heat per m2 via metabolism
than humans to prevent their body temperature from falling .
Which of the following captions best describes the figure below comparing exercise and
caloric expenditure? ** Answ** Figure 2. The effect of exercise on caloric
expenditure.
In order to measure the latency of a reflex or reaction on LabStation ** Answ** the
Marker should be placed at the beginning of the stimulus and the Point Selector should
be placed at the beginning of the response
In order to measure the rotation angle of a reflex or reaction on LabStation ** Answ**
the Marker should be placed at the beginning of the response and the Point Selector
should be placed at the peak of the response curve .
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