Lab 4 Primary growth - Portland Community College

Lab 4: Primary Body 1

Name: ______________________________________ Date/Lab time: _________________

Lab 4: Plant Anatomy I: The Primary Plant Body & Primary Growth

Supplies:

Coleus non-red variegated (living)

Celery stalk

Dicot stem x-sec (hollow and not hollow)

Ranunculus root tip l-sec

Monocot stem x-sec Zea (corn)

Syringa leaf x-sec

Coleus shoot tip l-sec

Live monocot stems ex. Asparagus, Canna Lily

Cabbage

Zea leaf x-sec

Ranunculus root x-sec (young and old)

Branch root slide x-sec

Germinating corn and bean

Older corn and bean

Leaf for epidermal peel (fava bean works well)

Phloroglucinol stain

Vocabulary to know: Apoplast, Axillary meristem, Casparian strip, Collenchyma, Endodermis, Leaf

primordia, Meristem, Mesophyll , Palisade , Palisade parenchyma, Parenchyma, Pericycle, Primary cell wall,

Primary plant body, Root apex, Rosette, Sclerenchyma, Secondary cell wall, Shoot apex, Spongy parenchyma,

Stele, Symplast, Tracheary elements, Vascular bundles

LAB SYNOPSIS:

This is a multi-day observation lab. We will examine microscope slides for the following:

3 major plant cell types (Parenchyma, Collenchyma and Sclerenchyma) within tissues.

3 major plant tissues (epidermis, vascular and ground) within organs.

3 major plant vegetative organs (stems, roots and leaves) within the primary plant body.

Introduction:

During this lab we will look at the internal tissues and cells of plants (plant anatomy). We will use

angiosperms as our model but will also look at other plant groups such as the conifers. The two major

classes of flowering plants, Monocot and Dicot differ in their arrangement of internal structures. We

will see that these two groups of angiosperms also have basic differences in some of their internal cells

and tissues. We will also explore the subject of primary growth and cell elongation.

ANATOMY OF THE PLANT BODY

Cells- the building blocks of living organism.

Tissues- made up of cells, organized to perform a specific function.

Organs- made up of tissues, organized to perform a specific function. The major organs of

plants are stems, roots, leaves and reproductive organs.

Cells of the Plant Body (prior to woody growth)

THREE CELL TYPES FOUND IN PLANTS (Parenchyma, Collenchyma and Sclerenchyma)

Plant organs and tissues consist of one or more of the following cell types: parenchyma,

collenchyma and/or sclerenchyma. These cell types are different based on their cell walls.


A. Parenchyma cells- most common cell type in non-woody plants. Parenchyma is made up

of living cells with generally thin primary cell walls. (the soft parts of the plants you eat like

potatoes and lettuce).

B. Collenchyma cells provides strength to the plant body and is found most often in growing

regions of some stems, some petioles and sometimes along veins in leaves. Collenchyma cells

are living and have elongated irregularly thickened primary cell walls. Stems and leaf petioles

that are strengthened by collenchyma are able to bend in the wind. (the “strings” of celery are

collenchyma cells). Collenchyma is not common to all species of plants.

C. Sclerenchyma cells also provide strength to the plant body but is more often found in parts

of the plant body where cell elongation is no longer taking place. Sclerenchyma is made up of

variously shaped cells (fibers and sclereids) that, in addition to their primary cell wall, have

thick, often lignified secondary cell walls that are laid down after cell elongation.

Sclerenchyma cells are often dead at maturity. Sclerenchyma is found in all plant organs and

makes up the bulk of water conductive tissues of plants (xylem and woody tissues).

We will examine these cell types within specific vegetative plant organs (stems, roots and leaves) below.

THREE MAJOR TISSUE SYSTEMS OF PLANTS (Dermal, Ground and Vascular)

There are three major tissue systems in the mature plant body. A tissue is defined as a group of cells that

perform a specific function within an organism. Each of these tissue systems is made up of several cell types.

The tissue systems will become clearer as we examine them in the basic vegetative plant organs (stems,

leaves and roots).

1. The Dermal Tissue System – the “skin” of the plant

The epidermis represents this tissue, which is the outer, single cell layer protective covering of the primary

plant body. This tissue is made up of a variety of parenchyma cells which make up the three major parts of the

epidermis:1. relatively unspecialized epidermal cells, 2. guard cells and 3. cells that form hairs (trichomes- in

stems and leaves, and root hairs- in roots).

A waxy cuticle often covers the outside of epidermis (waxy leaves or waxy fruit).

2. The Ground Tissue System – makes up the bulk of most plant organs (prior to wood)

Ground tissue in roots stems and leaves is usually parenchyma, however, collenchyma and sclerenchyma

cells may also be found. Ground tissue makes up most of the bulk of plant organs. Ground tissue plays different

functions such as photosynthesis, storage, secretion, etc.

3. The Vascular Tissue System– conducts water, minerals and organic nutrients through the plant

Vascular tissue system actually consists of two complex conducting tissues (xylem and phloem).

A. Xylem Tissue conducts water and dissolved minerals throughout the plant body. Water conductive cells are

called tracheary elements and are non-living, elongated cells with thick strong secondary walls containing

lignin. The tissue also contains living parenchyma cells.

Tracheids- found in conifers

Tracheids and/or vessel members- found in angiosperms


B. Phloem Tissue conducts organic nutrients throughout the plant body. Phloem is made up of conductive

cells that are living, elongated cells with thick primary cell walls (sieve cells or sieve tube members) and

specialized supporting parenchyma cells (aluminous cells or companion cells).

Sieve cells with aluminous cells- found in gymnosperms.

Sieve tube members with companion cells- found in angiosperms.

Both xylem and phloem may also have associated fiber cells. We will cover more structure/function of

vascular tissues later.

CELL AND TISSUE ARRANGEMENT IN ORGANS

We will now examine how cells and tissues make up the major vegetative plant organs (stems,

leaves and roots)

The Stem (Cells and Tissues)

The stem is defined by the presence of nodes and internodes. We will exam cross-sections of stems

in order to examine the tissue systems and cells present. The instructor will go over the major

anatomical features outlined below:)

*Your prepared slides have been differentially stained to show cellular and tissue details. Most are

stained with saffron (red) and Methylene blue. * do not memorize cell types by this staining (other

stains would give different results). Instead learn cell and tissue types by location, structure/function.

*Do not confuse air spaces with cells. In cross-section plant cells are often square with rounded

corners. Where 3 cells meet are often air spaces. These extracellular air spaces along with cell walls

and tracheary elements make up the non-living portion of the plant body, the apoplast. The apoplast is

a continuum throughout the plant body and is involved in water and mineral transport. Most living

cells of plants are physically interconnected via cell wall spanning plasmodesmata. These living,

intracellular parts of the plant body are thus also a continuum, which is termed the symplast.

I. Prepared slide of dicot stem cross section

On a separate piece of paper AND put in plant form table, draw a dicot stem cross section, identify and

label; cell types (parenchyma, sclerenchyma) and tissues (epidermis, ground tissue {pith and cortex},

vascular tissue {xylem and phloem}), clearly show the vascular bundles as a ring. Label the phloem’s

conductive cells (thin primary walled parenchyma that usually stain green) and phloem fibers (thick

secondary walled sclerenchyma that usually stain red). Remember to include this with your lab

manual!

1. Examine a prepared slide of a “Dicot” stem cross-

section.

*GROUND TISSUE: Notice the central region

surrounded by parenchyma tissue (pith). The pith,

along with the cortex (discussed below), make up

the ground tissue of the stem.

*VASCULAR TISSUE: Identify the ring of

vascular bundles. The large empty cells with red staining cell walls


located towards the inside of the vascular bundle are the xylem (lignin stains red with saffron).

The smaller empty cells with blue staining cell walls towards the outside of the vascular bundle are

conducting cells within the phloem. Smaller diameter red staining cells may often be seen outside the

phloem. These are phloem fibers.

Notice the parenchyma tissue occurring between the vascular bundles (pith rays).

* GROUND TISSUE: To the outside of the vascular cylinder is found the cortex. Both the cortex and pith

are part of the ground tissue. The cell walls of the ground tissue do not stain red. They lack lignin and are

thin cell walled parenchyma.

* EPIDERMIS: The outermost layer of cell is the epidermis. See if you can locate:

Trichomes- “hair-like” extensions from the epidermis

Stomata- holes for gas exchange

Cuticle- a layer of waxy material outside the epidermis.

II. Wet-mount of a dicot stem cross section

2. Make a wet-mount slide of a cross-section of a Dicot stem, Coleus. Stain the Coleus stem with

phloroglucinol. Phloroglucinol stains lignified cell walls red (i.e. sclerenchyma). Identify the parenchyma,

xylem, phloem and dermal tissues. Is collenchyma present? ______________

Collenchyma will appear as thickened cell walled cells. Unlike the thick cell walled sclerenchyma fibers,

collenchyma will NOT stain red with the phloroglucinol stain.

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III. Prepared slide of a monocot stem cross section

On a separate piece of paper AND put in plant form table, draw a monocot stem cross section, identify

and label; cell types (parenchyma, sclerenchyma) and

tissues (epidermis, ground tissue, vascular tissue {xylem

and phloem}) clearly show the vascular bundles as

scattered throughout.

1. Examine a prepared slide of Zea (corn). Corn is a

monocot.

*GROUND TISSUE: Unlike dicots, monocot stems lack

obvious pith and cortex. Other then the vascular bundles

areas inside the stem are referred to as “ground tissue”.

*VASCULAR TISSUE: Note that vascular bundles are

“scattered” in the monocot stem. Again the xylem is

towards the inside of the stem and the phloem is towards

the outside.

Corn vascular bundles look like Homer Simpson’s face. The

two eyes, nose and mouth are water conducting cells of the

xylem. The forehead is the organic conducting cells of the

phloem. His hair are phloem fibers.

* EPIDERMIS: The outermost layer of cell is the epidermis. Like seen in leaves, The following are present:

Trichomes- “hair-like” extensions from the epidermis

Stomata- holes for gas exchange

Cuticle- a layer of waxy material outside the epidermis.


IV. Wet-mount of a monocot stem cross section

2. Make a wet-mount slide of the cross-section of a monocot stem (ex. Canna Lily, asparagus or Hosta) and

stain with phloroglucinol. Note the epidermis, the scattered vascular bundles. The air spaces in the vascular

bundles form as the early tracheary elements are pulled apart as the stem grows.

Put your observation of monocot vs. dicot stems into your Plant Forms table.

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The Leaf (Cells and Tissues)

A leaf is defined by its formation (during its development, a leaf extends over and protects the shoot tip).

I. Prepared slide of dicot leaf cross section

1. Examine the prepared slide of a leaf blade cross-section of the Dicot Syringa (lilac). Note the features

described below. Be able to relate what you see under the microscope to figure below.

EPIDERMIS: The outermost layer of cell is the epidermis. Note the upper (adaxial) and lower

(abaxial) epidermis. Identify stomata and guard cells. Note that only certain cells of the epidermis

have chloroplast associated with them. Why?

Label the following (Cuticle , Epidermis, Guard cells, Palisades mesophyll, Phloem , Spongy

mesophyll, Xylem) A-G


2. Identify the vascular tissue of the leaf, which is organized into veins. Observe the midrib (major vein) of

Syringa. Again xylem will be the larger red stained cells while the phloem are smaller and stained blue. Note the

position of phloem and xylem. Does the position of the phloem and xylem within the leaf stay in the same

orientation as it emerges from the stem? In the stem, xylem is towards the inside, phloem towards the outside.

3. Identify the spongy and palisade parenchyma (mesophyll) of Syringa leaf. The parenchyma cells are the

ground tissue in the leaf. Notice the numerous chloroplasts within these photosynthetic cells. Also notice the

large amount of intercellular spaces present. These air spaces allow for increased uptake of CO2 for

photosynthesis.

4. Identify the leaf epidermis, noting the occurrence of guard cells on the abaxial and adaxial sides of the leaf.

6. Label the Dicot leaf cross-section (previous page). Label the major cell types discussed above and also

indicate the locations of each of the three tissue systems.

7. Make epidermal peels of both the abaxial and adaxial surfaces of a leaf as described by your instructor:) Try

to locate an area of your peel that does not have ripped up green mesophyll cells. Your peel should look almost

transparent. Examine peel under the lowest power of the compound microscope and count the number of

stomata present on the abaxial surface and of the adaxial surface. You are just looking for relative numbers

“fewer” “many”

Number of stomata on adaxial surface. (Few/Many)

Number of stomata on abaxial surface. (Few/Many)

8. Sketch and label cells of an epidermal peel.

label guard cells, stomata and regular epidermal cells. In which epidermal cells are chloroplasts located?

9. Make a slide of a cross-section of celery stalk. Grocery store celery is a rosette plant and the “stalk” is

actually a petiole, part of the leaf.

Look for the collenchyma cells, which occur in the stalk margins, below the epidermis. Now stain your celery

stalk with phloroglucinol.

Does the phloroglucinol stain indicate any lignin associated with the collenchyma?


Draw your celery cross section below. Label the collenchyma and the other major tissues you observe.

We will cover monocot leaves in the C3 C4 photosynthesis lab. So you

might wait to put your leaf observation into your Plant Forms table)

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The Root (Cells and Tissues)

Roots have a root cap and lack nodes and internodes.

I. Prepared slide of dicot root cross section

On a separate piece of paper AND put in plant form table, draw a

dicot root cross section, identify and label; cell types (parenchyma,

sclerenchyma) and tissues (epidermis, ground tissue {cortex}, vascular tissue {xylem and phloem}),

clearly show the stele (the central core of vascular tissue). Label the

phloem’s conductive cells (thin primary walled parenchyma that

usually stain green). Remember to include this with your lab manual!

1. Examine a prepared slide of a Ranunculus root cross-section

(younger, older). Note how it differs from stems.

*VASCULAR TISSUE: Identify the central core of vascular tissue

(the stele). Note the xylem forming a large red staining star shaped

pattern in the center. And the smaller green stained phloem in the

arches of the star.

On the younger root cross section, use 400X total magnification and

identify the endodermis, which is the innermost cell layer of the cortex.

Each cell of the endodermis has a band of red staining suberin, a waxy

material, in its cell wall. This band is called a Casparian strip. The

Casparian strip prevents water from moving into the stele without first

passing through the endodermis cell membrane. This allows plants to

select what types of material can enter into the plant body.

On the older root cross section, note how the endodermis is completely

encircled by suberin wax. This prevents any water in the stele from

leaking out.


Just inside of the endodermis is the pericycle. The pericycle is an area of meristematic cells in the

vascular tissue system which can give rise to branch roots (see branch roots below) and to woody

growth (see Secondary Plant Body lab).

*GROUND TISSUE: Outside the stele, all the way to the epidermis is the cortex (dicot roots lack a

pith). Also not all the purple staining starch.

* EPIDERMIS: The outermost layer of cell is the epidermis. See if you can locate:

Root hairs- “hair-like” extensions from the epidermis that increase water/mineral uptake. (I doubt

you will see these)

Suberin- in the older root section you may see suberin wax (staining red) coating the epidermis.

What function do you think this plays in older roots?

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II. Prepared slide of a monocot root cross section

On a separate piece of paper AND put in plant form table, draw a monocot root cross section, identify

and label; cell types (parenchyma, sclerenchyma) and tissues (epidermis, ground tissue, vascular tissue

{xylem and phloem}) clearly show the vascular bundles as a central ring.

1. Examine a prepared slide of Zea (corn) root. See

monocot/dicot slide. Corn is a monocot.

*VASCULAR TISSUE: Note that vascular tissue forms a ring

within the endodermis. Again the xylem is towards the inside of

the root and the phloem is towards the outside.

*GROUND TISSUE: Unlike dicots, monocot roots have a pith!

And a cortex. Note the central pith with surrounding vascular

tissue.

* EPIDERMIS: The outermost layer of cell is the epidermis.

III. Wet-mount of a monocot root cross section

Time permitting, make freehand cross-section of the root from the bean and corn plants you started in

the first lab. Stain sections with phloroglucinol and examine under the compound microscope.

(put your dicot and monocot root observations into your Plant Forms table)

If, on an exam, you should see microscope sections of stem/roots from monocots and dicots, be able to

tell them apart and be able to identify cells and tissues.

Example: How does the arrangement of the stele compare between Monocots and Dicots? How do

roots differ from stems?


PRIMARY GROWTH

Where does the plant body come from (stems, leaves and roots)? Primary growth occurs at the tips of plants,

the shoot and root apex and give rise to this primary plant body. The shoot apex is responsible for the

formation of stems and leaves. The root apex is responsible for the formation the root and the root cap. The area

of cell division in these apexes is called the meristem. The meristem produces 3 primary meristematic tissues.

1. Protoderm-develops into the epidermis, usually a single cell layer.

2. Procambium-develops into vascular tissues (phloem and xylem)

3. Ground meristem-develops into core tissues (cortex and pith).

The shoot apex

The shoot apex is a zone of meristematic tissue that gives rise to the stem, leaves and floral cells, tissues and

organs. The shoot meristem produces cells to one side, down. Thus, shoots grow “up”.

PROCEDURE- Label shoot tip

1. Use the microscope to examine a longitudinal-section slide of a Coleus shoot tip containing the shoot apical

meristem. Try to find the 3 primary meristematic tissues (the ground meristem vs. procambium may be hard to

tell apart). Notice the dark staining leaf primordia on either side of the apex,

2. Identify the youngest leaves and the pair of older leaves that is in the same plane. Note the young

axillary bud in each leaf axis of the older leaf pair.

Where do new stem branches come from? Recall axillary buds may later develop into branches or flowers.

3. Label the vegetative shoot tip of Coleus with:

Shoot apical meristem which contains 3 meristematic tissues (protoderm, ground meristem, procambium),

Axillary bud, Leaf primordia, Trichome

Draw an arrow showing the direction cells are produced to result in elongation of the shoot.

4. Look at the head of cabbage. It is a massive terminal bud. Examine a head of cabbage that has been cut

longitudinally. Notice the rounded shoot apex and the leaves occurring, along the compressed shoot axis.

Leaf axillary buds may be seen as small white bulges immediately above the center of each leaf base. Look

one of these axillary buds using the dissecting scope.

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The root apex

The shoot apex produces cells in 1 directions but the root apex produces cells in 2 directions’

giving rise to the root (above) and to the root cap (below).

PROCEDURE- Observation and label the

root drawing

1. Use the microscope to examine a

longitudinal-section of Ranunculus or

onion root tip (do we have this slide in the

slide box?).

Locate the meristematic region behind the

root cap. The root cells produced undergo

cell elongation pushing the root through

the soil.

Label the root apical meristem and put

arrows showing the direction cells are

produced in the root drawing

2. The area below the apex is the root cap.

Notice that it extends back beyond the

apex and surrounds it for some distance.

The root cap protects the root meristem as

it pushes through the soil. The root cap is

constantly shed and must be regenerated by the root’s apical meristem as the root pushes through the

soil.

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Where do new root branches come from?

Branch roots

Recall- in the stem, branches form at nodes from the growth of axillary buds. That is NOT how

branch roots form. Brach roots can form anywhere along the root, allowing for the root to respond to

soil conditions (more water, more nutrients, symbiotic associations, etc.)

1. Examine the slide of branch roots “Lateral Root Origin” to determine how longitudinal extension of

branch roots within the soil occurs. Note the development of the new root apical meristem. Note as

these new branch roots form they leave a wound and they rip through the cells of the original, parent

root!

Questions

I. Stem support system:

1. Which stem cells help to hold up the young parts of stems via turgor pressure?

2. Which stem cells help to hold up the older part of a stem even when turgor pressure is last?


3. Structure/Function: leaf epidermis

a. What structures of the leaf epidermis allow for gas exchange?

b. Why don’t regular epidermal cells (even in the leaf) have chloroplasts?

4. Why might it useful for a plant to have more stomata on the lower surface than on the upper surface

of their leaves?

5. Why is the endodermis essential in the root but not in the stem?

6. Recall branch roots may form anywhere along the root (branch roots do not form from axillary

buds). What advantage does this give a plant?

7. The meristems (in root and shoot tips) of plants continue to grow throughout their lifetime. Imagine

a 200-year old oak tree, with active meristems producing new leaves, buds, and flower shoots each

year. How does that compare to growth in animals like you?

8. What functions does the root cap provide?


Lab 4 Appendix microscope use brief

(Courtesy of Ansley, S. et al. Biology 112 Lab Manual, Cascade Campus)

Synopsis:

Microscope care

Microscope structure/function

Prepared slides vs. wet mounts

Introduction:

The compound light microscope is a tool used by biologist to extend the range of our vision.

Ordinarily, humans cannot see objects smaller than 0.1 mm in diameter, but the light microscope

renders objects as small as 0.2 microns (1 micron = 10-3mm).

Care for the microscope:

The microscopes we use in class are precise instruments designed for student work. They are durable

but can be easily damaged. The microscopes are expensive to repair and to replace.

Carrying- carry the microscope with two hands. One on the frame handle, the other on the base. Do not

tilt the microscope as the eyepieces can fall out.

Objective lens and stage position- when not being used and when stored, the stage should be in its

lowest position with the shortest objective lens in place. This minimizes the chances of damaging the

lens. This should also be the position when mounting specimens.

Viewing slides- always start with the lowest powered objective lens (the shorts lens). Mount your slide

with the stage in its lowest position. Raise the stage and focus down (see details below)

Lens cleaning- use only lens paper to clean lenses. Start with dry swiping before using lens cleaner.

Make sure lenses are completely dry.

Revolving turret- use the rubber grip when changing objective lenses. Using the lenses as a handle can

damage the lenses.

Storage- remove any slides and store with the stage in its lowest position and the shortest objective

lens in place. Wrap cord and return to cabinet position with the frame facing outwards, for easy

handling.

Procedure:

Locate all of the following parts of your microscope (and on Error! Reference source not found.).

1. Power Switch: turns light source on/off.

Turn microscope off if leaving it for more than a few minutes.

2. Light Intensity Knob: controls the intensity of the light passing through the slide.

Turn to the lowest setting before turning the microscope on/off.


3. Lamp: provides a light source.

4. Condenser: focuses and concentrates light on the specimen.

The Condenser can be raised and lowered. Usually you want the condenser all the way up, then down a

little bit

5. Iris Diaphragm Lever: controls amount of light transmitted by opening/closing.

!contrast! to maximize contrast, iris diaphragm should be mostly closed

6. Stage: flat structure on which the microscope slide is placed. (Stage should be at its lowest

position)

7. Coarse Adjustment Knob: used BEFORE fine adjustment to initially focus the specimen.

Note: Turning the knob causes the stage to move up or down.

8. Fine Adjustment Knob: “fine focuses” the image. Turning the knob causes the stage to move up

or down, but the movement is very small.

9. Specimen Holder: mechanism that holds the slide in place.

Pull back the “hook” on the right, insert a slide, and slowly release the

hook so it does not crack the slide.

10. X-Y Adjustment Knobs: controls slide movement from front to back

and controls slide movement from side to side.

11. Objective Lens: 4x objective

(scanning), 10x objective (low

power), 40x objective (high power),

100x objective (oil immersion lens)

12. Revolving Nosepiece (turret): Use

ring on nosepiece to move the

objective lenses – DO NOT grab

objective lenses to rotate nosepiece.

13. Ocular Lens (Eyepiece):

magnification value of 10X.

Caution: Do not remove oculars!!

Dirt or dust may enter the system.

Total magnification = objective

value multiplied by ocular value.


Exercise 1: Compound Microscope Set-up and Magnification

Equipment Needed:

Prepared slide

Procedure:

1. Lift / carry / move microscopes with two hands—one under the base and the other around the

upper arm of the stand.

2. Do not slide a microscope to move it on a table—it may damage parts, including the light bulb.

3. Plug in electrical cord.

4. Make sure that the stage is all the way down by lowering it with the coarse focus knob. This will

give you plenty of room to work.

5. Make sure that the lowest power objective (4X) is clicked into position. Note: The magnification

on the lowest power objective is 4X, indicating that the image is magnified 4 times compared with

the naked eye. On a compound microscope, additional magnification is offered by the eyepiece. On

a microscope with a 10X eyepiece, the total magnification is 4 x 10, or 40X (the image appears 40

times larger than it would to the naked eye). When specifying magnification, always use the total

magnification.

Total magnification

What is the power of the ocular (eyepiece) lens on your microscope?_________

What would the total magnification of a specimen be if you were using:

4X objective lens. Total magnification of image____________



100X objective lens. Total magnification of image___________

6. Turn on the light. You may need to adjust the light intensity (usually this is set to the highest level).

(if no light appears in the filter mount area, return light setting to the lowest, click the power

switch, and repeat).


Exercise 2 – Exploring the Field of View

7. Get a prepared slide (a stem or root cross section)(you will need to look at these for lab 4B). Before

mounting; If the slide is dirty, fog it with steam from your breath and clean it using a paper towel.

Also locate the specimen, note where it is, its color and

orientation on the slide.

8. Mount the slide right-side-up onto the stage of the microscope.

Move the specimen holder lever and position slide into the

corner of the holder. The slide should be flat and squarely

placed. Slowly release the specimen holder lever. Do not allow

the holder to spring back quickly against the slide; this can cause

damage to the slide.

9. Move the specimen into the center of the light using the X/Y adjustment knobs.

10. Always start with the lowest power objective lens (4x). This is the easiest lens to focus with; it

has the highest depth of view and offers high contrast.

11. Always focus down. This prevents accidently running the slide into the objective lens.

So, raise the stage to its highest position without hitting the objective lens (Note: the 4x objective lens

is too short to hit the slide:).

12. Ocular lens. Looking through the oculars, slowly lower the stage using the coarse adjustment

until the specimen comes into focus. Adjust the light as needed using the light intensity knob

and/or the iris diaphragm.

13. Using the stage control knobs, center the specimen in your field of view.

14. Adjust with the fine focus until a sharper image appears (this should require less than one turn of

the fine focus knob).

Describe the relationship between the orientation of the specimen on your prepared slide when you

looked at with the naked eye and the image of the specimen viewed through the compound

microscope. _____________________________________________________

15. Parfocal- The compound microscope is designed to stays in focus when magnification is

changed. This means that as you change objective lens you should not need to make major changes

to focus (rise or lower the stage).

16. Increase magnification by rotating the 10X objective into place. Note: the 10X objective will

not hit the slide. Use the fine adjustment knob to bring your specimen back into focus. Do not use

the course adjustment knob.

17. You may need to adjust the lighting. As magnification increases, the amount of light decreases.

Describe the relationship between magnification and the amount of the specimen that can be seen

through the compound microscope.


18. Increase magnification by rotating the 40X objective into place. Note: the 40X objective is very

close to the slide but will not hit the slide. Use the fine adjustment knob to bring your specimen

back into focus. Do not use the course adjustment knob.

19. Finishing up. To remove slide, lower stage all the way down, rotate the 4X objective lens back

into place and remove slide. Your microscope should now be ready for the next activity.

Exercise 3: Making a Wet Mount Slide of Coleus

Equipment Needed:

1 compound microscope

Glass slide

Cover slip

Coleus

Procedure:

1. Cut off a section of Coleus stem. On a cutting board, use a sharp razor blade to make a number

of thin sections (cutting at a slight angle can help assure at least on side is thin).

2. Place a small drop of water on a slide. Add a thin Coleus stem cross section.

3. Add one drop of phloroglucinol. Phloroglucinol stains lignified cell walls red. This will help

you identify sclerenchyma (fibers and tracheary elements of the xylem)

4. Place a cover slip on slide at a 45° angle, touching to the edge of the drop of liquid. Drop the

cover slip gently.

5. For clean-up, carefully remove the cover slip and put in the broken glass container (or the trash

if it is a plastic cover slip). Wash and dry the glass slide. Return it to the box of slides.

A. What is the purpose of placing the cover slip on slide at a 45° angle to the drop of liquid and

touching to the edge before you drop it?

B. What is the function/result of changing the diameter of light from the iris diaphragm in the

condenser lens?

Lab 4 Primary growth - Portland Community College

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