Biology Lab Exam 1

Why is it important to start with the scanning objective in place, rather than the high-power objective?

To minimize the possibility of breaking slides and coverslips or scratching lenses.

True or false: The coarse-focus adjustment knob should be used with scanning objective, low-power objective, and the high-power objective.

False

If a 4× objective is used, what is the total magnification of a microscope?

-40x

Which objective lens will give you the greatest resolving power?

The oil-immersion objective.

To move a specimen to the upper left-hand field of view, which way must one move the slide?

To the lower right.

As magnification increases, what happens to the amount of light?

Decreases.

With increased magnification, what happens to the field of view?

Decreases

As magnification increases, what happens to the depth of field?

Decreases

______________ is the distance between the objective lens and the specimen.

Working distance

Why is a coverslip placed on a slide at a 45-degree angle?

It will minimize the number of air bubbles forming beneath the coverslip.

Why are wet mounts used to view biological specimens in the laboratory?

To observe fresh tissues and living organisms.

A student wants to study the legs of an insect and the margin, or edge, of a leaf. Which microscope is the best choice?

Stereomicroscope

What is TEM and what types of materials are studied using it?

Transmission electron microscopy; study ultrastructure of cells and biochemicals.

What is SEM and what types of materials are studied using it?

Scanning electron microscopy; study surface features of specimens.

When should an oil-immersion objective be used?

To view minute details or bacteria.

Which microscope uses regular light for illumination but has a special condenser to accent minute differences in the refractive index of structures within a specimen?

Phase contrast

What is the advantage of parfocal objectives?

After the image is focused with a parfocal objective, it is in focus with the other objectives and requires only minor adjustments in focusing.

What is not a step needed to prepare a wet mount?

Slide the wet mount underneath the oil-immersion lens.

True or false: When you move the letter "e" slide toward you, the letter "e" moves toward you.

False

What is the relationship between plane of focus, depth of field, illumination, and magnification?

As magnification increases and illumination decreases, the plane of focus and depth of field decrease.

What is the magnification of a microscope with a 10x ocular and a 100x oil-immersion objective?

1000×

Which of the following is not a rule to remember when focusing a microscope?

Lift the stage to better view the specimen.

Scientific notation is a way of expressing ____________.

all of the numbers

For the number 4.5 × 10, which represents the base?

10

For the number 6.8 × 10, the 7 is called the _________.

exponent

When multiplying numbers written in scientific notation, you should ______ the exponents.

add

When adding and subtracting numbers written in scientific notation, all the numbers should be converted to the same ________ value.

exponent

Why is the use of scientific notation important?

It helps make extremely large and small numbers easy to work with.

What does a negative exponent signify in scientific notation?

It signifies a number less than 1.

What are the advantages of using the metric system? Select all that apply.

The metric system is standard except in a few countries.

It is easier to shift a decimal place than deal with fractions.

What are the three basic units of measurement for the metric system?

Meter, kilogram, and liter.

True or False: Reading the meniscus of a fluid in a graduated cylinder made of glass is easier compared with one made of plastic.

True

Why is taring a balance important?

Taring standardizes the balance by accounting for the mass of cups or other material.

Liquid nitrogen is nitrogen cold enough to exist in the liquid form. It has a boiling point of -320.4°F. Convert this value to degrees Celsius.

-195.8°C

What is the standard unit for measuring temperature in the metric system?

Kelvin or degrees Celsius

Conversion between metric units is performed by doing what?

Shifting the decimal place.

True or false: An acid is a substance that accepts a hydrogen ion in solution.

False

True or false: Acids have a sour taste, and bases have a bitter taste.

True

True or false: Bases are also known as alkalines.

True

True or false: Bases increase the hydrogen ion concentration of aqueous solution or accept hydroxide ions (OH-) in solution.

False

The pH scale has a range from 0 to ____. A substance with a pH less than 7 is considered a/an ____ and a substance with a pH greater than 7 is a/an ____.

14; acid; base

If tomato juice has a pH of 3, how many more H+ ions are present in lemon juice with a pH of 2?

It has 10 times more H+ ions.

True or false: Purple cabbage, hydrangea, and elderberry extracts make excellent natural pH indicators.

True

What are ionic bonds?

Ionic bonds are bonds formed by the attraction of oppositely charged ions.

What are examples of an ionic bond?

Sodium chloride (NaCl) and potassium chloride (KCl)

Magnesium oxide (MgO) and calcium oxide (CaO)

What is a nonpolar covalent bond?

Nonpolar covalent bonds are strong bonds that result from an equal sharing of electrons.

What are examples of a nonpolar covalent bond?

Methane , pentane , and octane

What is a polar covalent bond?

Polar covalent bonds are strong bonds that result from an unequal sharing of electrons.

What are examples of a polar covalent bond?

Water , peptide bonds, and amines

True or false: Bases contribute 1 or more hydrogen atoms to a solution when it dissociates in water.

False

True or false: Acids have a pH greater than 7.

False

True or false: Acids react with certain metals, which results in liberation of hydrogen gas.

True

True or false: The chemical compound released by a bee sting is an example of a base.

False

True or false: Carbonated water is an example of an acid.

True

True or false: Sodium hydroxide (NaOH) is an example of a base.

True

An old saying is "oil and water don't mix." What happens when oil and vinegar are put in the same container?

The nonpolar oil floats atop the polar vinegar because oil is less dense than vinegar.

Disaccharide

double sugars like sucrose & lactose

Monosaccharides

single sugar composed of 3-7 carbon atoms like ribose & glucose

Polysaccharides

complex carbs. can be linear or highly branched like cellulose & chitin

Disaccharides & Polysacharridea

made by dehydration synthesis

Which of the following are true for lipids?

fats, waxes, & phospholipids are examples

Lipids are insoluble in water & soluble in non polar compounds like ether

What is an essential amino acid?

An amino acid that cannot be synthesized by the organism & must be supplied in the diet

What is glycogen?

Glycogen is a highly branched, glucose-rich polysaccharide. Stored in the liver & the skeletal muscle of animals. Forms when glucose is hydrolyzed

Sudan III

test for lipids, changes to orange red

Benedict's reagent

tests for reducing sugar, changes from blue to green, yellow, orange, or red depending on the amount present

Biuret Reagent

tests for proteins, changes from blue green to violet

Iodine test

tests for starch result: turns sample Blue/Black if starch is present

Saturated Fat

Only single bonds w max H atoms

Solid at room temperature

Animal fats & vegetable shortenings

Unsaturated Fat

Best for a healthy lifestyle

Lipid at room temperature

Fish oils & plant oils

At least one double bond

Waxes & Lipids include

plant cuticles & cerumen

Waxes are

composed of alcohol bonded with a long-fatty acid chain

Fats are

important for insulation & cushioning the body

Triglycerides

most abundant lipids in your body and the richest source of energy

Many fruits can be used to isolate DNA, but strawberries yield more DNA. Why is this true? Select all that apply

Strawberries are octopoid (contain 8x the amount of DNA)

Have pectinase which breaks down the cell wall & releases DNA

Have cellulase which does the same at pectinase

At the end of the procedure, what do you do with the cloudy, stringy mass of DNA in order to observe it?

winding the DNA slowly around a clean glass stirring rod

The addition of alcohol to the strawberry extract causes ___ to precipitate out of the solution

DNA

Define diffusion.

The random movement of molecules from regions of greater concentration to regions of lesser concentration.

The rate of diffusion is ___________ related to concentration, temperature, and pressure meaning that an increase in concentration, temperature, or pressure results in an ___________ in the rate of diffusion.

directly; increase

What is not one of the three parts that make up a nucleotide?

Histone

Made of pentose sugar, phosphate molecule, & nitrogenous base

Which of the following occur in the DNA replication process?

At the start of each DNA segment to be replicated, RNA polymerase builds an RNA primer.

Termination of the process occurs when a stop codon is encountered.

RNA primer attracts an enzyme known as DNA polymerase.

Purines

Pyrimidine, Thymine

Pyrimidine

Guanine, Uracil, & Adenine

tRNA

Always attaches to specific amino acids

Is a loop of 3 bases that is complementary to the codon.

mRNA

Works in triplets to form codons that specify amino acids in protein synthesis.

Is a single strand of nucleotides whose bases are complementary to those of the DNA from which it was transcribed.

rRNA

Is composed of two subunits (large and small).

Is made inside the nucleolus.

One strand of the DNA serves as a direct template for the new strand, and the other strand is pieced together and comprises a new strand. This statement best describes _____________.

semiconservative nature of DNA replication

Order the following steps of translation in the proper sequence.1. The codons are read three at a time and all of the amino acids are joined by peptide bonds.2. The anticodon of a tRNA with a methionine amino acid will base-pair with the start codon.3. The stop sequence appears after which protein folding occurs.4. The large ribosomal subunit attaches to the small ribosomal subunit.5. The mRNA associates with a small ribosomal subunit.6. The small ribosomal subunit will align with the start codon.

5, 6, 2, 4, 1, 3

What is the significance of the AUG codon in protein synthesis?

It initiates translation.

How do introns differ from exons?

Introns do not code for proteins.

Introns have regulatory functions.

During hurricanes, saltwater is blown into freshwater marshes. What kind of solution is the saltwater, and why do many of the freshwater plants die?

Hypertonic; the saltwater draws the water out of the plants.

The major function of the plasma membrane of a cell is to regulate materials going into and out of the cell. It is described as selectively permeable. What is unique about this membrane?

It allows for the movement of certain substances into and out of the cell.

What is the most important factor that determines the rate of diffusion in biological systems?

temperature

concentration

pressure

What are the main passive transport?

Diffusion

Osmosis

Facilitated diffusion

Filtration

Ingestion of foreign substances by macrophages and yeast cells by an amoeba is known as _____________.

phagocytosis

Permeability of a plasma membrane to a given molecule is dependent on the particular molecule's characteristics of _____________.

size

charge

lipid solubility

A medical technologist notes after observations under the microscope that in one of the samples to be tested, many red blood cells are crenated. Give a possible explanation for this observation.

now in hypertonic solution

Turgor pressure results when plant cells are placed in a hypotonic solution. Why don't the cells burst?

Plant cells are surrounded by a rigid cell wall.

A red blood cell is placed in a hypotonic solution. What is the fate of the cell?

The cell will lyse.

Converting between metric units is easier than converting between English units because you only need to _______.

move the decimal point

When reading a graduated cylinder, you should read the meniscus, which is the ________ of the curve.

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