7/29/2019 Week 5 Labs

1/39

Week 5

SYCPA Regents Prep

Living

Environment

Labs 1-5

7/29/2019 Week 5 Labs

2/39

Week 5 - Labs

2

This packet provides a review of concepts that may be tested in the NYS Living Environment

Regents and is based on the NYS Core Curriculum. This course will cover individual topics over 6 weeks

as listed below:

Week 1 - Scientific MethodWeek 2 - EcologyWeek 3 - Human Body Systems

Week 4 Molecular Biology & GeneticsWeek 5 - LabsWeek 6 - Evolution & Human Impact

The order of these topics is chosen based on their average weight in past Living Environment

Regents.

The individual packets will consist of a review for the specific topic followed by past regents

questions.

Good Luck!

SYCPA Say Yes Collegiate Prep Academy

7/29/2019 Week 5 Labs

3/39

Week 5 - Labs

3

Labs Review

Instrumentation Review

Stereo Microscopy

Stereo Microscope

The image at the left is that of a dissecting orstereo microscope.

Notice that it has only two sets of lenses, including the eyepiece. Thespecimen to be observed is an opaque object (light does not passthrough it). The observer sees the surface of the dissection specimen or

other specimen being studied. This specimen is placed in a containeron the stage of the microscope.

Light Microscopy

Biologists use the light microscope to observe microscopic specimens. This microscope is also called the

compound microscope is given its name because it has more than two sets of lenses. It has an eyepiece lens (orocular) and two or more sets of objective lenses (this microscope has three lenses) on a nosepiece that usuallyrevolves. This kind of microscope is also called a light microscope as it requires a source of light to pass through

the specimen. The specimen observed with this kind of microscope is usually microscopic and has to betranslucent (allows light to pass through it). The specimen to be observed is placed on the stage of this

microscope.

Parts of the Light Microscope

1. eyepiece or ocular2. body tube3. fine adjustment knob4. nosepiece5. high power objective6. low power objective7. diaphragm8. mirror (many microscopes have

a light instead)9. base10.coarse adjustment11.arm12.stage clip13. inclination joint

7/29/2019 Week 5 Labs

4/39

Week 5 - Labs

4

Functions of the Light Microscope Parts

eyepiece (ocular) - where you look through to see the image of your specimen. body tube-the long tube that holds the eyepiece and connects it to the objectives (not labeled) fine adjustment knob-small, round knob on the side of the microscope used to fine tune the focus of your

specimen after using the coarse adjustment knob

nosepiece-the rotating part of the microscope at the bottom of the body tube; it holds the objectives high power objective -- used for high power magnification of the specimen (the longer objective lens) low power objective -- used for low power magnification of the specimen diaphragm-controls the amount of light going through to the specimen light or mirror-source of light usually found near the base of the microscope; makes the specimen easier

to see

base-supports the microscope coarse adjustment knob -- used for focusing on low power arm-part of the microscope that is grasped when one carries the microscope stage clips-shiny, clips on top of the stage which hold the slide in place

(The specimen is placed on the stage for viewing.)

inclination joint -is used to tilt the microscopeSome Microscope Usage Rules

Always carry the microscope with two hands - one on the arm and one underneath the base of themicroscope. Hold it up so that it does not hit other objects.

Do not touch the lenses. If they are dirty, ask the teacher for special lens paper or ask your teacher toclean the lenses for you.

If using a microscope with a mirror, do not use direct sunlight as the light source. Blindness can result. Ifusing a microscope with a light, turn off light when not in use.

Notify teacher if a slide or cover slip breaks. Students should not handle broken glass. Always clean slides and microscope when finished. Store microscope set on the lowest power objective

with the nosepiece turned down to its lowest position (using the coarse adjustment knob). Covermicroscope with dust cover and return it to storage as directed by your teacher.

Other Points About the Compound Microscope

1. Always begin focusing on the lowest possible power. Remember to center the specimen youare observing in the field of view before switching to a higher power. Make certain that youmove the objectives away from the specimen when focusing so their is no collision between

the objective being used and the slide/cover slip which may damage the objective lens.

2. As you switch from low to high power, the field of view becomes darker. To deal with thisthe diaphragm needs to be opened to allow in more light. (Frequently on low power thediaphragm needs to be partially closed as it is too bright.)

7/29/2019 Week 5 Labs

5/39

Week 5 - Labs

5

3. As you switch from low to high power the field of view becomes smaller.

Images viewed under the light microscope

are reversed (backward) and inverted(upsidedown). This is a compound light microscope

view of the letter F placed on a slide in itsnormal position.

Chromatography

Paper chromatography is a procedure used to separate substances in a mixture. In the LivingEnvironment/Biology lab, this mixture is usually a solution of liquid plant pigments containing different kinds of

chlorophylls and other colored photosynthetic pigments.

A small concentrated sample of a mixture is placed on the chromatography paper above the line of a solventmixture. The paper is contact with a solvent solution at its bottom. This solvent moves through the paper due tocapillary action and dissolves the mixture spot. Some parts of the solvent mixture to be separated have a greater

attraction for the chromatography paper, so they move a lesser distance, while other parts of the solvent mixturehave a lesser attraction, so they move a greater distance up the paper.

Paper Chromatography Apparatus

7/29/2019 Week 5 Labs

6/39

Week 5 - Labs

6

Completed Paper Chromatography of a Plant Pigment

The specific mixture placed on chromatography paper will separate into consistent patterns as long as the samesolvent, paper, and amount of time allowed for the separation are not changed.. Different solvents will change the

separation pattern of the mixture. Mixtures that are colored can be separated into component colors by paperchromatography.

The Rf value of a pigment is a statistic often computed from a chromatography separation. Each component of a

solution. Each pigment in the solution will have a specific Rf for the same solvent when the chromatographyoccurs for a specific length of time.

Calculation of Rf

Rf =distance the pigment travels from the original spot of solvent

distance to the wetting front of the solvent

Electrophoresis

Gel electrophoresis is a procedure used to separate charged molecules of different sizes by passing them through agel in an electrical field. The gel serves to act as a support for the separation of the molecules of different sizes.

The gel is usually composed of a jelly-like material called agarose which is made from seaweed.

Electrophoresis Setup

7/29/2019 Week 5 Labs

7/39

Week 5 - Labs

7

Molecules such as DNA fragments of differentlengths and proteins of different sizes are oftenseparated in the gel. Holes are created in the gel

which serve to hold the particular DNA mixtures tobe separated. The DNA fragments are then loaded

into the wells in the gel.

Separation of DNA

The gel contains very small holes which act toregulate the speed which molecules can move

through it based on the size of the molecules.The smaller molecules will move much more

easily through the small holes in the gel. As aresult, large fragments of DNA lag behindsmall fragments, thus allowing theexperimenter to separate these molecules

based on their size.

Sometimes molecular weight markers are electrophoresed along with the specimen, so the experimenter mayknow the size of the DNA fragment which has been separated. Different individuals or organisms form different

banding patterns in the plate when their DNA has been separated. DNA is cut into pieces for separation forelectrophoresis by restriction enzymes.

These enzymes were originally discovered in bacteria and were used by the bacteria to defend themselves from

invasion by other bacteria and viruses.

Some Uses for the Gel Electrophoresis DNASeparation

1. It may be used to determine an individual's geneticrelationship to his or her ancestors, as the moreclosely matched the banding pattern between twoindividuals, the more closely they will be genetically

7/29/2019 Week 5 Labs

8/39

Week 5 - Labs

8

related. In theory, no two individuals will form thesame DNA banding pattern when the electrophoresisis completed.

2. It may be used to identify an individual that havecommitted crimes based on the ability to match thesuspects DNA to evidence which has been collected

at a crime scene.

3. It may be used to determine evolutionary relationshipsbetween organisms, as organisms with a closer

genetic relationship will form more similar bandingpatterns.

Electrophoresis Setup with Power Supply

Measurement Review

Volume Measurement

A commonly used instrument to measure liquid volume is the graduated cylinder. This instrument usuallymeasures liquid volume in milliliters (ml).

Using a Graduated Cylinder

7/29/2019 Week 5 Labs

9/39

Week 5 - Labs

9

It is important to remember to read to thebottom of the curved lineormeniscus when measuring solutions

involving water or most liquids. Thegraduated cylinder at the left is divided

into increments of 2 ml, so the volume init is 12 ml. The graduated cylinder on

the right is divided into increments of 1ml, so the volume in it is 16 ml.

Mass Measurement

The triple beam balance is commonly used to measure mass in the biology lab. This device is named for its threelong beams on which sliding bars called riders (or tares) are used to determine the mass of an object placed on its

platform. It is very important that the riders on the rear beams are in the notch for the whole number of grams andnot in between notches. The front beam is a sliding scale graduated in grams. The rider on this beam can be

positioned anywhere on the scale. Masses on a triple-beam balance can be read to tenths of a gram and estimatedto hundredths of a gram.

Using the Triple Beam Balance

The picture at the upper left showstwo different models of triple beam

balances commonly used in the

biology laboratory. The picture at thelower left shows the measurement of

a mass in progress. Withoutestimation, the mass of the object

appears to be 373.3 grams (g).

Length Measurement

Most measurements in biology will involve metric units of measurement. It is good to start at a whole numberincrement that isn't 0. Many times the end of a ruler will be worn away by student/teacher use or is inaccurate due

to the manufacturing process. It is important to remember to take away the whole number increment one hasmoved in on the ruler (in the example below 1 cm) from the measurement obtained.

Using a Ruler to Measure Length

7/29/2019 Week 5 Labs

10/39

Week 5 - Labs

10

Problem: How long is leaf A?

The tip of the leaf is at about 6.5 cm, but note the measurement started

at 1 cm. Therefore, Leaf A is 5.5 cm or 55 mm in length.

Microscopic Measurement

The magnifying power of most objectives and oculars is engraved on them. On the ocular, the marking can be

found on the top edge or on the smooth cylinder that fits inside the body tube; on the objectives, magnification ison the side of the cylinder. For example, a marking "10x" means that the particular lens forms an image ten timeslarger than the object being viewed. The total magnification of a microscope is equal to the power of the eyepiece

(ocular) X power of the objective used. For example, if a student is using a microscope with a 10 X ocular and a43 X high power objective, the total magnification of the specimen the student is viewing is equal to 10 X 43 or430 X (times).

Formula for Total Microscope Magnification

Total magnification =Power of the

eyepiecex

Power of

theobjective

The size of a microscopic field of view can be determined on low power using a device called an opticalmicrometer. An economy version of this can be made by placing a clear metric ruler on the stage of a microscopeand using it to estimate the field of view. The light microscope is used to look at cells or other similarly sizedmicroscopic objects, so small units of measure such as millimeters or micrometers are used. It is important toremember that there are 1,000 micrometers in 1 mm (millimeter) and 1000 millimeters in a meter.

Finding the Size of a Microscope Field of View

In the pictured field of view at the left, it can beobserved that there are approximately 3 1/2 divisions

equal to a length of 3.5 mm. Therefore this field ofview is equal to 3.5 mm

or 3,500 micrometers.

Finding the Size of Multiple Cells in a Field of View

7/29/2019 Week 5 Labs

11/39

Week 5 - Labs

11

The two cells in this field take up a field of view of onemillimeter. Therefore, the size of the specimen is equal to 1mm/2 cells or 0.5 mm per cell. There is 500 micrometers in

0.5 mm., so the average size of each cell is 500 micrometers.

Estimating Cell Size When the Field of View is Known

It is often difficult to approximate the approximate size of the field of view, but this amebaconsidered lengthwise appears to occupy approximately 1/3 of the field of view. The field of view inthe left image is 3 mm. Given that the ameba in the image takes up about 1/3 of that field, we canfind its approximate length by multiplying the 3 mm X 1/3 = 1 mm length or 1,000 micrometers forthe approximate length of this ameba.

The student is viewing the same ameba in the field of view at the right on a higher power. The fieldof view gets smaller which makes the ameba appear larger in this field.

Indicators and Stains

Indicators

An indicator is any substance used to assist in the classification of another substance. There are many differentkinds of indicators. Some common kinds of indicators used in Living Environment/Biology will be indicated

below.

7/29/2019 Week 5 Labs

12/39

Week 5 - Labs

12

The pH Scale

Acids and bases (alkalis) are common substances studied in science.

The pH scale is used to indicate the relative strength of an acid of base. ThepH scale goes from 0 to 14. A pH of 7.0 is considered to be neutral. Thegreater the pH is than 7.0, the more basic the substance is. The lower the

pH is below 7.0, the more acidic a substance is.

Stomach acid has a pH of approximately 2.0.

Some Common Indicators

1. Litmus paper turns red or a shade of red in

acids. Litmus turns blue or a shade of blue inbases. It is important to place a few drops or a

small amount of the substance to be tested on thelitmus paper when testing it. Do not dip the

litmus paper in the substance to be tested. Apaper which provides a more specific indication ofthe pH level of a substance is pH paper. This

paper turns different shades of various colorswhich may be compared to a scale to determine the

pH value.

2. Bromthymol blue is an indicator used to showthe presence of either carbon dioxide in solution or

an acidic solution. Low levels of carbon dioxideor acid will result in the bromthymol blue solution

remaining blue, while higher levels of carbon

dioxide or acid will result in the bromthymolsolution taking on a yellow tint. Frequently thisindicator is used in biology labs to indicate

photosynthetic activity (solution turns blue as CO2

is used) or respiratory activity (solution turnsyellow as CO2 is added to the solution).

7/29/2019 Week 5 Labs

13/39

Week 5 - Labs

13

3. Lugol's solution (which is actually IKI) is abrown solution which turns black in the presence

of starches. The test tube at the right showsLugol's (iodine) solution mixed with a starchsuspension.

4. Benedict's solution is used to detect thepresence of simple sugars such as glucose. When

a simple sugar is mixed in Benedict's solution andheated for a short period of time in a test tube, it

goes through a variety of color changes, eventuallyending as an orange-red or brick red color. Theuse of Benedict's solution before and after using itto detect the presence of the simple sugar glucose

is shown in the pictures on the right.

Stains

Very frequently it is helpful to dye certain cell structures so that they can be seen more clearly. Chemicals thatdye parts of cells for this purpose are called stains. Two commonly used stains in the biology laboratory areLugol's iodine solution and methylene blue. Lugol's solution is a good stain to make the nuclei of plant cells standout more prominently. It has the unfortunate drawback of killing the cells it used on however. Methylene blue is

often used to stain animal cells, such as human cheek cells, to make their nuclei more observable. It is vital dyewhich does not immediately kill the specimen.

Using Stains in Biology

These are plant cells stained withLugol's solution so

their nuclei are visible.

These are human cheek cells stained

with methylene blue solution making their nucleiand outlines much more visible.

7/29/2019 Week 5 Labs

14/39

Week 5 - Labs

14

Correctly Staining Specimens

1. A specimen is obtained and placed on the slide with forceps. A cover slip is then lowered on tothe specimen from an approximately 45 degree angle gently. This reduces the number of air

bubbles the specimen will have. The student then places a drop or two of water on the specimen.

2. The student places a drop of stain beside and under one corner of the cover slip.3. The student places a towel on the opposite side of the cover slip in the water beside the cover

slip. This will draw the stain through the entire specimen in a few seconds without removing the

cover slip. This technique will also remove any air bubbles which have formed. The stainedspecimen may now be observed. Note that this technique can be used to draw salt water ordistilled water into a specimen having a cover slip over it without removing the cover slip as

well.

Dichotomous Keys

A dichotomous key is a sequence of steps that allows the identification of a living thing. The key will consist of aseries of choices that lead the user to the correct name of a given item. The term dichotomous means that therewill always be two choices in each step of the key until the organism is correctly identified.

Some Key Ideas in Dichotomous Key Construction

1. Use constant characteristics rather than ones that disappear or vary with the season or other

environmental factor.2. Use characteristics which can be directly observed.

7/29/2019 Week 5 Labs

15/39

Week 5 - Labs

15

3. Use quantitative measurements with an amount or dimension rather than vague terms like "big" and"small."4. Precede the descriptive terms with the name of the anatomical part to which it applies.

Rules to Follow When Using a Dichotomous Key

1. Always read both choices, even if the first seems to be the logical.2. Understand the meaning of the terms involved in the key.3. When measurements are given, use a scale to measure the specimen. Do not guess at a measurement.

4. Living things are always variable, so do not base your organism identification in the field on a singleobservation.

Using a Dichotomous Key to Identify an Organism

The example below will illustrate the use of a dichotomous key to identify the unknown creature above.

Steps in theDichotomous Key

Identification Process

Taxonomic Key to Stream Water Animals1. A. With a shell go to 2

B. Without a shell go to 3** The creature clearly does not have a shell, so go to# 3.

2. A. Shell made of two parts heldtogether by a hinge Clam

B. Shell made of onlyone part Snail

3. A. Body flat, ovaland brown Water Penny

B. Body not exactly like a

water penny go to 4

** This creature does not have an oval body it is long,so go to # 4.

4. A. With six

jointed legs go to5

B. With more than sixjointed legs go to 12

C. With less than six jointed legs; body

often worm-like go to 14

** The creature has 6 jointed legs, so go to # 5.

5. A. With two or three thin, ** The creature has three thin tails, so go to # 6.

7/29/2019 Week 5 Labs

16/39

Week 5 - Labs

16

hair-like tails go to 6B. Without thin,

hair-liketails go to 7

6. A. With one hook at the end of each

leg; usually with three tails,

sometimes only two Mayfly

B. With two hooks at the end of eachleg; two tails Stonefly

** This organism clearly has three tails and only asingle hook at the end of each leg whichmakes it a Mayfly larva.

7 A. Body with many long,pointed parts go to 8

B. Body not exactly

like this go to 98. A. Body brown or black, often

very large HellgrammiteB. Body white, yellow or tan; not

so large Beetle larva9. A. Body with hook-like claws attail end; animal sometimes

protected with bits ofsand, pebblesor twigs Caddisfly

B. Body without hook-likeclaws go to 10

10 A. Body small, dark, hard andbeetle-like Riffle beetle

B. Body not exactly likethis go to 11

11 A. With 3 wide tails DamselflyB. Without tails, but with three

short points Dragonfly

12 A. With two large claws and eightlegs; large Crayfish

B. Without large claws;

smaller go to 13

13. A. Body flattened side to side;

usually white ScudB. Body flattened top to bottom;

usually gray Sowbug

14. A. Body with very small legs; usually

with a head go to 15B. Body without any legs or

head go to 16

15 A. Tail-end of body wider than the

We didn't need to go beyond step 6 with the organismwe classified above, but some organisms mightrequire the use of many more steps

before its proper identification

7/29/2019 Week 5 Labs

17/39

Week 5 - Labs

17

other Black fly larvaB. Tail-end of body not

wider Midge16. A Body brown, plump, and

caterpillar-like Crane fly larvaB. Body not exactly like

this go to 1717. A. Body with suckers at

each end Leech

B. Body without suckers; small, thinand worm-like Aquatic worm

Dissection

Anatomical Direction

Before beginning a dissection, it is important to have an understanding of some of the basic directional

terminology associated with the dissection of specimens. Some of these terms include proximal, which meanstoward the body, and distal, which means to move away from the body. Other important anatomical directions are

indicated below.

Key Anatomical Directions

Dissection Safety

Proper safety procedures when working with dissection tools and specimens is of greatest importance. Somesafety rules to engage in when dissecting specimens are as follows.

Dissection Safety Rules

Follow all instructions given by your teacher.Inform your teacher of any illness as a result of exposure to chemicals used in specimen preparation.

7/29/2019 Week 5 Labs

18/39

Week 5 - Labs

18

Avoid contact with preservative chemicals. Rinse the specimens completely before dissection.Know where the eye-wash fountain is if needed.Wear safety goggles to prevent the splashing of any chemicals into the eyes.Properly mount dissection specimens to dissecting pan. Do not dissect a specimen while holding it.Handle scalpel or razor blade (safety edged) with extreme care.Always cut away from your body and away from others.Never ingest specimen parts.Never remove specimens or specimen parts from the classroom -- until the dissection is completed allparts of the dissection must remain within the dissecting pan.

Properly dispose of dissected materials.Store specimens in as directed by your teacher.Clean up the work area and return all equipment to the proper place when the dissection is completed.Wash hands after each dissection.

Dissection Equipment

Dissection Equipment

The pictured dissection equipment from leftto right is (1.) a teasing or dissectionneedle which used to pull apart muscletissue, (2)dissecting scissors which are usedto cut through tissue, and (3) a scalpel,which is a knife used to slice through and

cut tissue.

Plant Dissection

Many kinds of flowering plants, such as lilies, daffodils, or tulips are commonly subjects for dissection inbiology. The flower is the plant structure specialized for reproduction in advanced plants. The processes of

meiosis and fertilization occur in the flower.

Some Key Flower structures

petals: colored parts inside the sepals which attract insects

sepals: structures which are usually green outside the petals which help to protect the flower

7/29/2019 Week 5 Labs

19/39

Week 5 - Labs

19

stamen: forms the male reproductive organ and consists of an anther and a filament

anther: pollen box in which pollen grains are formed containing the genetic material which produces sperm

filament: supports the anther

pistil or carpel: female reproductive organ which consists of three parts

stigma: found at the top of the pistil, is often sticky and hairy adapting it to catch and hold pollen

style: tube-like connection between the stigma and the ovary

ovary: enlarged part of the pistil attached to the receptacle (stem tip on which the flower rests) and contains the ovules

ovules: small white structures within the walls of the ovary which produces the plant egg cells

Animal Dissection

The dissection of animals is important for many reasons. It helps in the learning about the internal structures ofanimals. It also allows students to learn how organs and tissues are interrelated. Another purpose of dissection isto allow the comparison of organisms in terms of their organs and relative complexities. While many good

simulations of dissections may be observed, it seldom can replace the benefits of the actual participation in anactual dissection.

Some common vertebrate organisms dissected in the living environment lab include the frog and the fetal pig.Usually the dissection procedure involves tying the organism down firmly on the dissection pan, cutting the

organism open on its ventral side (as pictured below), and pinning its tissues and muscles back to observe itsinternal organs. Different teachers may have their own preferences in terms of their emphasis on the tissues andorgans to be observed in a dissection.

Key Internal Organs of the FrogOrgan Body System Major Function

brain nervous thinking and coordination of body activities

heart circulatory pumps blood through the body

stomach digestive stores and begins the chemical digestion of food

smallintestine

digestivefinishes chemical digestion and absorbs digestednutrients into the blood

liverdigestive (and othersystems)

makes bile, detoxifies poisons, many other functions

gall bladder digestivestores bile from liver for release into small intestine toaid in fat digestion

lungs respiratoryexchanges gases with the external environment (aided by

the skin in the frog)

kidneys excretory filter wastes from the blood

ureter excretory carries wastes to the urinary bladder

7/29/2019 Week 5 Labs

20/39

Week 5 - Labs

20

urinarybladder

excretory stores urine before its release from the body

pancreas endocrine/digestiveproduces hormones like insulin which regulate bloodsugar, produces pancreatic juice which aids in digestionin the small intestine

ovaries reproductive makes eggs in female frog

testes reproductive makes eggs in male frog

Frog Internal Anatomy

Provided by Regentsprep.org and The NYS Core Curriculum

7/29/2019 Week 5 Labs

21/39

Week 5 - Labs

21

Lab Regents Questions

August 2011

7/29/2019 Week 5 Labs

22/39

Week 5 - Labs

22

7/29/2019 Week 5 Labs

23/39

Week 5 - Labs

23

7/29/2019 Week 5 Labs

24/39

Week 5 - Labs

24

7/29/2019 Week 5 Labs

25/39

Week 5 - Labs

25

7/29/2019 Week 5 Labs

26/39

Week 5 - Labs

26

June 2011

7/29/2019 Week 5 Labs

27/39

Week 5 - Labs

27

7/29/2019 Week 5 Labs

28/39

Week 5 - Labs

28

7/29/2019 Week 5 Labs

29/39

Week 5 - Labs

29

7/29/2019 Week 5 Labs

30/39

Week 5 - Labs

30

Jan 2011

7/29/2019 Week 5 Labs

31/39

Week 5 - Labs

31

7/29/2019 Week 5 Labs

32/39

Week 5 - Labs

32

7/29/2019 Week 5 Labs

33/39

Week 5 - Labs

33

7/29/2019 Week 5 Labs

34/39

Week 5 - Labs

34

7/29/2019 Week 5 Labs

35/39

Week 5 - Labs

35

7/29/2019 Week 5 Labs

36/39

Week 5 - Labs

36

7/29/2019 Week 5 Labs

37/39

Week 5 - Labs

37

7/29/2019 Week 5 Labs

38/39

Week 5 - Labs

38

7/29/2019 Week 5 Labs

39/39

Week 5 - Labs