Biology Lab Midterm
Test tube ____ (letter) indicates a negative reaction for the presence of starch using the iodine test.
D
Chambers A and B are placed next to each other, but are separated by a film similar to a cell membrane. Chamber A contains 80% carbon dioxide and Chamber B contains 20% carbon dioxide. Which of the following will occur?
Some carbon dioxide will move from chamber A to chamber B.
When Elodea leaves were placed in 10% NaCl, what was the result?
The cell membrane shrank away from the cell wall because the solution was hypertonic.
Why do you think it is a good idea to soak wilted lettuce in cool water before serving it?
The water is a hypotonic solution relative to the cytoplasm in the plant cells, so the plant cells will gain water and the lettuce will become crisper.
During the time that the particles are diffusing into the cell
a point is eventually reached where equal numbers are passing into and out of the cell.
What must water pass through during osmosis?
a semipermeable membrane
A solution is a mixture of a
a solute dissolved in a solvent
All other factors being equal, solute molecules diffuse most rapidly through
air
The biuret test would indicate a positive result for proteins in which of the following solutions?
albumin
47.0 miligrams =
all answers are correct
The Benedict's test indicates a positive result when the solution turns
all choices are correct
Which of these will affect the rate of diffusion?
all of these options
transmission electron microscope
analogous to the compound light microscope; object is ultra-thinly sliced and treated with heavy metal salts to improve contrast
scanning electron microscope
analogous to the dissecting light microscope; gives an image of surface and dimensions of an object
In the following figure, which cell exhibits the condition of plant cells that have been placed in an hypotonic environment?
b
Which of the following reagents is best suited for the detection of protein?
biuret test
Which color change represents a positive reaction for the presence of sugar using the Benedict's test?
blue to orange
Which of the following tests is best suited for the detection of fat and oils?
brown paper
Which of the following tests is used to detect the presence of lipids?
brown paper test
In the following figure, which cell exhibits the condition of plant cells that have been placed in an hypertonic environment?
c
What is the basic unit of life?
cell
What prevents a plant cell from bursting in a hypotonic solution?
cell wall
What type of microscope do we use in lab?
compound light microscope
In order for diffusion to occur, there must be a
concentration gradient
What determines the direction of diffusion?
concentration gradient
eukaryotic cell
contains nucleus
Biuret reagent contains __ ions which react with peptide bonds under the alkaline conditions of the reagent and produce the color change associated with the presence of protein.
copper
stereomicroscope (dissecting microscope)
designed to study entire objects in three dimensions at low magnification
In the metric system exercise, you measured the __ of three circles.
diameter
Small lipid soluble molecules would move through the plasma membrane by
diffusion
How does rate of diffusion depend on the speed of molecular motion?
directly; faster moving molecules result in faster diffusion
To convert a smaller unit of measure to a larger one you would __ a factor.
divide by
nucleus
eukaryotic cell that is enclosed by a nuclear envelope and contains nucleoplasm
When combing an acid and water, always
first water, then add acid
Whether in a gas, a liquid, or a semisolid, diffusion always occurs
from high to low solute concentration
During osmosis water will move in which direction?
from the area with lower solute concentration to the area of higher solute concentration
hypertonic
having a higher concentration of solute than another solution.
hypotonic
having a lower concentration of solute than another solution
In simple diffusion, molecules move from an area of ____ concentration to an area of ____ concentration.
high, low
Assuming that all of the following substances are permeable across a selectively permeable membrane, which of the following molecules would you predict to move fastest across the membrane?
hydrochloric acid (mw = 36)
A cell is placed in a 15% solute solution and the cell shrinks. What is the tonicity of the 15% solution solution?
hypertonic
A(n) _______ solution has a lower concentration of water than the cell placed in the solution.
hypertonic
After soaking for one hour in a solution of unknown concentration, a slice of potato appears to be very soft and limp. You can determine that the solution is
hypertonic
What type of solution causes cells to swell?
hypotonic
Which of the following reagents is best suited for the detection of starch?
iodine test
When a person requires intravenous administration of fluids which type of you expect to most commonly use?
isotonic
A semipermeable membrane is placed between two solutions. The membrane is only permeable to water. On the RIGHT side is a 10% salt solution. On the LEFT side is distilled water (100% water). In which direction will a net movement of water occur?
left to right
organelles
little organs
Microscopes must have what two features to be effective?
magnification and resolution
resolution
minimum distance between two objects at which they can still be seen, or resolved, as two separate objects
To convert a larger unit of measure to a smaller one you would __ a factor.
multiply by
The image shows a Biuret test to determine the presences of protein. Is it positive or negative?
negative
The image shows a iodine test to determine the presences of starch. Is it positive or negative?
negative
prokaryotic cell
no nucleus
A cell contains intracellular fluid that is approximately 0.9% nonpermeating solutes. If this cell is placed into 5% salt solution what direction will net water movement occur?
out of cell
Which direction is the net movement of water when a cell is placed in a hypertonic solution?
out of cell
What word describes a microscope that remains in focus when the objective lenses are changed?
parfocal
The cytoplasm is enclosed by ______ _________.
plasma membrane
Starch, cellulose, glycogen, and polypeptides are all made from chains of many subunits, or building blocks. What is the name given to a chain composed of many subunits?
polymer
Starch is a(n)
polysaccharide
The image shows a Benedict test for reducing sugar. Is it positive or negative?
positive
All living things are classified as _____ or _______.
prokaryotic, eukaryotic
The spreading out of molecules from a center of higher concentration is the result of
random movement of molecules
plasma membrane
regulates the movement of molecules in and out of the cytoplasm
In the weight exercise, the tare button was used to
reset the scale
Cytoplasm contains _____.
ribosomes for protein synthesis
Since the cell membrane allows some molecules to pass through it and will not allow others, it can be described as
selectively impermeable
A membrane allows water through but will not allow any solutes to pass. What type of membrane is this?
semipermeable
organelles
small membranous bodies that have specific structure and functions.
The positive control for the Iodine test was the
starch solution
cell theory
states that all organisms are composed of cells and that cells only come from other cells
What kind of microscope would we use to study a whole or opaque object?
stereomicroscope
What is meant by the tonicity of a solution?
the effect a solution has on the volume of a cell
cytoplasm
the material enclosed by the plasma membrane and cell wall
compound light microscope
used for examining small or thinly sliced sections of objects under higher magnification
What is the correct way to smell a substance?
wafting
isotonic
when the concentration of two solutions is the same
In the Tonicity in Potato Cells lab,
when water entered the cells it caused the potato to stay crisp.
Which color change represents a positive reaction for the presence of starch using the iodine test?
yellow to purple
What is the freezing point on the Celsius temperature scale?
0 degrees Celsius
Assume you drink 250 mL of soda out of a 1 liter soda bottle. How many liters are left?
0.75 liters
Select the unit of weight that is the heaviest.
1 kilogram
How many centigrams are in a gram?
100
How many centiliters are in a liter?
100
How many centimeters are in a meter?
100
What is the boiling point on the Celsius temperature scale?
100 degrees Celsius
1,000,000 milliliters equals __ liters.
1000
kilo
1000
mili
1000th
centi
100th
deci
10th
low
10x
Normal human body temperature on the Celsius scale is approximately
37 degrees Celcius
If the diffusion rate of one crystal of potassium permanganate within a liquid is 240 mm/hour, predict how far one crystal of potassium permanganate would diffuse within 10 minutes?
40 mm
high
40x
scanning
4x
Which of the following reagents is best suited for the detection of sugar?
Benedict's test
Which of the following tests requires heating prior to observing the results?
Benedict's test
Which reagent is sued toe detect the presence of simple sugars?
Benedict's test
What is diffusion?
Movement of molecules from high to low concentration
What is osmosis?
the movement of water across a semipermeable membrane
What factors are responsible for the osmotic pressure of a solution?
the number and type of solute particles it contains
When looking at your data from the effect of concentration on the rate of diffusion lab, what occurred to the rate of diffusion as time elapsed?
the rate of diffusion decreased for all three concentrations of potassium permanganate crystals
As molecular weight increases...
the rate of diffusion decreases
In a semi-solid, if the concentration of the solute is increased,
the rate of diffusion increases
Tonicity in cells refers to the concentration of solute in a solution outside of a cell, relative to
the solute concentration of the cytoplasm inside the cell.
When testing tonicity of red blood cells, if the solution became transparent after adding blood cells, you could assume
the solution was hypotonic and the cells had burst.
Proteins do not pass through plasma membranes because
they are very large molecules
