ZOO Quiz 1 (Labs 1 & 2, Microscopes & Porifera)

Describe the features of a compound microscope:

1. 2 sets of lenses to obtain high magnification

2. Provides a 2D image (light from below)

3. Inverted image (backwards & upside down)

4. For very small, thin, transparent specimens/cross sections

Describe the features of a dissecting/stereoscopic microscope:

1. Lower magnification than compound

2. Provides a 3D image (light from above & below)

3. Image in same direction (not inverted)

4. For larger, opaque specimens & manipulating/dissecting

Describe what each of the following microscope components (compound microscopes) do:

1. Ocular lenses

2. Body

3. Arm

4. Stage clips

5. Power switch

6. Light intensity adjustment dial

7. Stage adjustment knobs

8. Nosepiece

9. Objective lenses

10. Stage

11. Condenser

12. Iris Diaphragm

13. Fine-focus adjustment knob

14. Coarse-focus adjustment knob

15. Illuminator

16. Base

1. Ocular lenses: lenses nearest the eye through which you look

2. Body: housing that keeps ocular & objective lenses in proper alignment

3. Arm: supports microscope body, stahe, & adjustment knobs

4. Stage clips: hold slide in steady, stationary position

5. Power switch: turns microscope light on/off

6. Light intensity adjustment dial: dimmer switch that permits the adjustment of light intensity

7. Stage adjustment knobs: moves the stage to center the slide under objective lenses

8. Nosepiece: revolving housing that supports objective lenses

9. Objective lenses: lenses of different magnification that work in conjunction with ocular lenses to magnify the image; located just above the stage

10. Stage: supports slides

11. Condenser: lens mounted beneath the stage that focuses light beam on specimen; for contrast/light, often used in conjunction with the iris diaphragm

12. Iris Diaphragm: Mounted beneath the stage near the condenser; regulates amount of light illuminating specimen

13. Fine-focus adjustment knob: permits precise focusing

14. Coarse-focus adjustment knob: moves stage up or down to focus image

15. Illuminator: source of light

16. Base

Which microscope components are light controls that control the focus and quantity of light applied to the specimen?

1. Light intensity adjustment dial

2. Condenser

3. Iris Diaphragm

Which microscope components do dissecting/stereoscopic microscopes have?

1. Ocular lenses

2. Binocular head

3. Body

4. Magnification control

5. Objective lens

6. Focusing control

7. Arm

8. Stage plate

9. Base

Define each term:

1. Field of view

2. Working distance

3. Depth of field

4. Resolution

5. Light intensity requirement

1. Area you can see through a lens

2. Space between the lens & specimen

3. Range in which the specimen is still in focus without needing to refocus the microscope (lower magnification has a greater depth of field b/c you can see more of the specimen in focus).

4. Details you can see

5. Smaller lenses need more light & vice versa

How do you calculate a microscope’s magnification?

Multiply the Objective Lens magnification by the Ocular Lens magnification (which is 10X).

For a compound microscope, what is the orientation of the specimen on the slide as seen through the ocular lens?

Backward and upside down, moves opposite

For a dissecting microscope, what is the orientation of the specimen on the slide as seen through the ocular lens?

Normal, in the same direction as the slide, moves in the same direction too

1. Under which objective lens (low or high magnification) is the field of view largest?

2. Under which objective lens (low or high magnification) is the field of view smallest?

1. Low magnification

2. High magnification

Which objective lens (low or high magnification) gives you the largest working distance (space to work under the lens)?

low magnification

Which objective lens (low or high magnification) has the greatest depth of field?

low magnification

As magnification increases, depth of field ______.

decreases (less of the object is in focus)

Which level of magnification (low or high magnification) requires the most illumination for the best clarity and contrast?

high magnification (it has the smallest lens for light to shine through, so needs more light)

If you have a transparent/thin specimen, would you need to open the iris diaphragm (to allow in more light) or close the iris diaphragm (to allow less light)?

Close the iris diaphragm - to not wash out the specimen

If you have a microscope with a 10X ocular lens and a 40X objective lens, what is the total magnification?

400X

When compared to most compound microscopes, stereoscopic/dissecting microscopes have a:

1. _______ working distance

2. _______ depth of field

3. _______ field of view

4. _______ magnification

5. _______ resolution

1. larger working distance

2. larger depth of field

3. larger field of view

4. lower magnification

5. lower resolution

Which objective lens magnification should you always start with?

The lowest

Is it okay to ever touch the slide with the lens?

No

For a lower magnification lens (5X compared to 50X, for example), describe if the lens has a larger/smaller or higher/lower characteristic than the higher magnification lens:

1. Field of view

2. Working distance

3. Depth of field

4. Resolution

5. Light intensity requirement

1. Larger

2. Larger

3. Larger

4. Lower

5. Lower

Describe each Phylum Feature for Sponges:

1. Classification:

Phylum Porifera

Classes:

1. Calcarea

2. Hexactinellida

3. Demospongiae

4. Homoscleromorpha

Describe each Phylum Feature for Porifera:

1. Organization level

Cellular level organization (no true tissues)

Describe each Phylum Feature for Porifera:

1. Embryonic development

Don’t undergo embryonic development

Describe each Phylum Feature for Porifera:

1. Symmetry

Asymmetry

Describe each Phylum Feature for Porifera:

1. Skeleton/Support

Spicules & Spongin

Describe each Phylum Feature for Porifera:

1. Movement/Locomotion

Motile as larvae, Sessile as adults

Describe each Phylum Feature for Porifera:

1. Sensory/Nervous

No sensory/nervous system

Describe each Phylum Feature for Porifera:

1. Digestion/Feeding

Uptake via choanocytes; nutrient transport via amoebocytes; filter feeders

Describe each Phylum Feature for Porifera:

1. Excretion/Osmoregulation

Cellular excretion; waste released out of osculum; diffusion

Describe each Phylum Feature for Porifera:

1. Circulation/Internal Transport

No TRUE circulation

Describe each Phylum Feature for Porifera:

1. Respiration/Gas Exchange

Cellular respiration

Describe each Phylum Feature for Porifera:

1. Reproduction

Asexual or sexual, monoecious and dioecious

What is volume vs. surface area?

Which one is crucial for a cell to be able to do more things (gas exchange, signaling, nutrient gain)?

• Volume: the need of a cell/organism

  • The amount of 3D space an object occupies

  • In a cell: how much stuff is in the cell

• Surface Area: the ability to supply that need

  • The amount of area exposed to the surface

  • In a cell: it's the size of the cell membrane

The more surface area, the more things a cell can do!

What is the main constraint of the surface area to volume ratio (the main issue)?

As an object increases in size, volume increases faster than SA.

• 2x in size = 4x in SA = 8x in V

The bigger you get, the harder it is to supply the need! - Limits cell size

How can animals overcome the SA:V ratio problem? In other words, how can an animal ensure they have a high SA:V ratio?

1. Be small

2. Be flat

3. Fold things in (Sponges!)

   1. Sponges have lots of inner cavities that increase diffusion to cells

T or F: Sponges can grow back parts.

True, because they have no true tissues, only cells

Where on the Kingdom Animalia tree do Porifera appear?

More distantly related to all other animals; on the furthest out branch directly connected to Clade Metazoa

Name the 4 general sponge cell types.

1. Porocyte

2. Choanocyte

3. Pinacocyte

4. Amoebocyte

What do these word roots mean to help us identify things?

• -cyte

• -pyle

• -coel

• -cyte = cell

• -pyle = hole

• -coel = cavity

Describe the Porifera cell type Porocyte.

• Cells that are small pores (donut-shaped) which form the ostia in asconoids.

• Channel water to choanocytes.

• The hole through the center of them is the prosopyle.

Describe the Porifera cell type Choanocyte.

• Creates a water current with its flagellum

• Filters food particles with its collar (sucks in food, releases water)

• Becomes sperm during sexual reproduction

• The amount of surface which is covered by choanocytes is critical for the SA:V ratio in sponges

Describe the Porifera cell type Amoebocyte.

• Digest food particles and transport nutrients to other cells

• Produce spicules & spongin

• Becomes eggs during sexual reproduction

• Totipotent: can turn into any other cell type

• Found in space between pinacocytes and choanocytes where structural elements like spicules & spongin reside

Describe the Porifera cell type Pinacocyte.

• Make up outer layer of sponge called the pinacoderm

  • Pinacoderm is not considered an epidermis because sponges have no tissues

The sponge body wall has what 3 components?

1. Outer layer with incurrent pores (has pinacocytes & porocytes)

2. Mesohyl (middle layer): a non-cellular protein matrix with spicules, spongin, & amoebocytes

3. Inner layer with choanocytes

What 2 structural support components do Porifera have? What are they made out of? What do they do?

1. Spicules: made of calcium carbonate and silica; give rigidity to sponges; compose the “skeleton”

2. Spongin: protein-based compound that gives sponges their “sponginess”; flexible fibers that support the sponge body

As sponges get larger, how do they adapt to get a higher SA:V ratio?

They fold into more complex shapes & body types

Name the 3 body types/plans in sponges from least to most complex.

Asconoid, syconoid, leuconoid

Describe the characteristics and features of Asconoid sponges.

How does water flow through Asconoid sponges?

Smallest & simplest body form (really tiny, need microscope to see entire specimen)

Features:

• Ostium/ostia: openings where water flows in; formed entirely by porocytes

• Choanocyte layers: line the spongocoel

• Spongocoel: body cavity/atrium

• Osculum: top opening where water & waste exits

Water flow: Ostium → spongocoel → osculum

Describe the characteristics and features of Syconoid sponges.

Which features are different than in asconoid sponges?

How does water flow through Syconoid sponges?

Larger body form than asconoid sponges; requires adaptation to increase its surface area = folds.

Features:

• Ostium/ostia: Mouth of the incurrent canals (not the mouth of porocytes)

• Incurrent Canals: gaps between the fingers

• Prosopyle: pore in membrane where water flows from incurrent canal to radial canal (still the hole in porocytes)

• Radial Canal: inside of the finger; lined with choanocytes

• Choanocyte layers: capture food particles for the sponge

• Apopyle: opening from radial canal to spongocoel; neck of finger

• Spongocoel

• Osculum

Different features than Asconoid:

1. Incurrent canal

2. Radial canal

3. Apopyle

4. Ostia mean something different too

Water flow: Ostium → incurrent canal → prosopyle → radial canal → apopyle → spongocoel → osculum

Describe the characteristics and features of Leuconoid sponges.

How does water flow through Leuconoid sponges?

Largest & most complex body form; has complex sets of flagellated chambers where choanocytes are found for more nutrient uptake.

Features:

• Ostium/ostia: Mouth of the incurrent canals

• Incurrent Canals: initial channels from ostia

• Prosopyle: opening where water flows from incurrent canal to flagellated chamber

• Flagellated Chamber: lined with choanocytes

• Apopyle: opening where water flows from flagellated chamber to excurrent canal

• Excurrent Canals: channels between flagellated chamber and spongocoel

• Spongocoel

• Osculum

Water flow: Ostium → incurrent canal → prosopyle → flagellated chamber → apopyle → excurrent canal → spongocoel → osculum

What are the ecological benefits of sponges on aquatic systems?

Can filter huge volumes of water quickly - alter microclimate of their habitat

• Rid water of organic debris, create circulating current

Also serve as food source for other organisms

Describe Class Calcarea in Phylum Porifera.

• Little spiky spicules (like little tubes)

• Have spicules made of calcium corbonate

• Very small (10cm or smaller) & pale

• Mostly found in shallow water

• All 3 body types found in this class

• All are marine

Describe Class Demospongiae in Phylum Porifera.

• Often brilliantly-colored

• Spicules made of silica & fibers made of spongin

  • Some lack spicules & may only have spongin

• 90% of sponges are in this group

• Occur in marine environments & is the only class with freshwater sponges

• All have leuconoid body types & all large sponges belong to this class

Describe Class Homoscleromorpha in Phylum Porifera.

• Looks like brains

• Sponge is a fairly thin layer growing on a base of calcium carbonate

• Few spicules made of silica & spongin

• All are leuconoid

• Mostly occur in shallow marine waters, using caves/walls/overhangs

• Evidence larvae may have some tissue level organization

Describe Class Hexactinellida in Phylum Porifera.

• Glass sponges

• Have spicules made of silica: often fused forming elaborate skeleton

• Intermediate body plan between syconoid & leuconoid

• Most found in deep ocean, some in shallow waters in polar regions

• Venus flower basket in this group

  • Shrimp symbiosis

What cell type in sponges is responsible for producing the water current through the sponge?

Choanocytes

What cell type is responsible for distributing nutrients to other cells?

Amoebocytes

Sponge “skeletal support” made of calcium carbonate or silica is:

Spicules

T or F: All 3 sponge body types are found in Class Calcarea.

True

What are the 3 different body planes (ways specimens can be dissected)?

What is it called when the entire organism is on a microscope slide?

1. Sagittal (longitudinal section)

2. Frontal (longitudinal section)

3. Transverse (cross-section)

Whole Mount

What is the order of Linnaen Taxonomy?

Kingdom, Phylum, Class, Order, Family, Genus, Species

Define these terms when looking at body planes:

• Anterior

• Posterior

• Dorsal

• Ventral

• Proximal

• Distal

• Medial

• Lateral

• Sagittal

• Transverse

• Frontal

• Anterior: toward the front of the body

• Posterior: toward the back of the body

• Dorsal: toward the back or upper side

• Ventral: toward the belly or lower side

• Proximal: closer to the point of attachment or origin

• Distal: farther from the point of attachment or origin

• Medial: toward the midline of the body

• Lateral: away from the midline of the body

• Sagittal (plane): divides the body into left and right portions

• Transverse (plane): divides the body into head and tail portions

• Frontal / Coronal (plane): divides the body into top and bottom portions