summary of laboratory exercises for midterm

1. ZOOLOGY
(LABORATORY)

2. EXERCISE 1: MICROSCOPES

3. MICROSCOPE
• A compound microscope consists of certain
precise mechanical parts (chiefly of metal) to
support and facilitate the use of optical parts (of
glass) that provide the magnified image.
• Although compound microscopes are very
common, the microscopes used in the
laboratory are Trinocular microscopes

4. MICROSCOPE
• Trinocular microscope has two eyepieces
but with a third eyepiece tube for connecting a
microscope camera. It is a binocular with a
moving prism assembly in which light is either
directed to the binocular assembly of the
microscope or to the camera.

5. Parts of a Compound
microscope
Parts of a Trinocular microscope

6. Specimens:
Cut-out of letter e
Skin hair
Mosquito Larva
These are the desired images of
the specimens under a
microscope (taken from the
internet and not the actual photos
from the experiment).

7. • The letter “e” as viewed in the microscope is positioned
upside down while the skin hair and mosquito larva, is
observed to have been magnified, its parts were seen
accordingly, based on the objectives used.
• Low Power Objective (LPO) has a magnifying power of 10x
which means that the specimen is 10x magnified when it is
viewed under the microscope. Meanwhile, HPO (High Power
Objective) has a magnification of 40x which means that, the
specimen viewed under the microscope is magnified 40x.
Thus, specimens are more visible and clear when it is viewed
under HPO rather than LPO. However, only a part/ fraction will
be seen under HPO depending on what you have focused.

8. EXERCISE 2: MAGNIFICATION

9. MAGNIFICATION
• It is defined as the number of items an object is
enlarged or reduced by a lens system.
• It is important to identify the magnification
especially on the microscope used to know how
many times a specimen is magnified and how
it actually differs as seen in the naked eye.
Microscope Magnification:
• Linear Magnification (LM) is the product of the
ocular magnification and the magnification of the
objective or:
• LM = OcM X ObM

10. Linear Magnification (LM)
• Using the Trinocular microscopes, since the
ocular is stamped 10x,
• LM at LPO (Low Power Objective, 10x) :
LM= 10x (10x) = 100x
• LM at HPO (High Power Objective, 40x):
LM= 10x (40x) = 400x
(Note: Scanner, stamped 4x as an objective which is not usually used
to focus but only to scan and have greater field of view of the
specimens before viewing on LPO and HPO, has LM = 10x (4x)=40x .)

11. Magnification of the Drawing
• Formula:
M = SD / SO
• Where:
• M= magnification of the drawing
• SD = size of the drawing
• SO = actual size of the object
(Note: Always remember that the size of the drawing is given
and the actual size of the objects, seashell/ starfish is
measured using a ruler, in mm or cm)

12. EXERCISE 3: CELLS

13. Cells
• It is the structural and functional unit of life
• The study of cell, its structure, and its activities is known as
Cytology (now evolved into its progressive alter ego, Cell
Biology)
• Although cells show great diversity in form and function,
all cells are built to a fundamental design and share certain
common features.
• There are two types of cells: Prokaryotic (no true nucleus)
and Eukaryotic (membrane-bound nucleus) organisms.
• In this exercise, we focused on examining Eukaryotic
organisms as such are Animal cells
(oval/spherical/irregular-shaped) and Plant cells
(rectangular shaped).

14. Specimens:
Animal cells:
• Cheek cells
• Human blood cell
• Chicken egg
Plant cells
• Onion cells
• Stomata with guard cells
• Preserved specimen (monocot/dicot stem, Hydrilla
verticillata)

15. Animal Cells
(with some of its parts)
These are the desired images of the specimens with its parts that can
possibly be seen under a microscope (taken from the internet and not
the actual photos from the experiment).
Cheek cell (400x)
Human blood smear (400x)
Erythrocytes (red blood cells) are
only evident

16. Animal Cells
(with some of its parts)
Chicken egg when cracked open (labeled)

17. Animal cell parts
• The description below of the parts of an animal cell that
can obviously be seen using the microscopes:
• Cell membrane/ Plasma membrane – the thin limiting
membrane enclosing the cell
• Cytoplasm – materials/ the matrix between the cell
membrane and nuclear membrane
• Nucleus- usually oval or spherical body found or near
center of the cell that is darker or more heavily stained
(Note: These parts are visible when stained with iodine solution)

18. Animal cell parts
• The description below of the parts of chicken egg:
• Yolk – the inner yellow portion of the egg
• Albumin – the egg white, surrounds the yolk
• Vitelline membrane – the thin delicate membrane that
surrounds the entire ovum
• Chalaza- the twisted albumen on the opposite poles of the
yolk
• Blastodisc (germinal disc) – a minute island of whitish
cytoplasm floating on the yolk which will give rise to a new
individual

19. Plant Cells
cytoplasm
Peel of Onion cell
Usually in scraping off
an onion, the parts
that are evident
when viewed under a
microscope are the ff:
Cell wall, cell
membrane,
cytoplasm and
nucelus.
Stomata with guard
cells
These are the desired images of the specimens
with its parts that can possibly be seen under a
microscope (taken from the internet and not
the actual photos from the experiment).
Cell membrane

20. Preserved specimens (Plant)
MONOCOT
Hydrilla verticillata
These are the desired images of the
specimens with its parts that can
possibly be seen under a microscope
(taken from the internet and not the
actual photos from the experiment).

21. Plant cell parts
• The description below of the parts of plant cell that can
obviously be seen using the microscopes:
• Cell walls – the “lines” forming the network between the
individual cells are nonliving cell walls composed chiefly of
cellulose
• Cell membrane – the layer immediately beneath the cell
wall. This encloses the cell cytoplasm.
• Nucleus – appears as a rather dense body in the
transparent cytoplasm; in some cells, the nucleus seems to
belying centrally and will look circular.
(Note: These parts are visible when stained with iodine
solution)

22. Plant cell parts
• Stomata (stoma) with guard cells
-Pores in a plant’s cuticle through which water vapor and
gases (CO2 & O2) are exchanged between the plant and the
atmosphere
• Chloroplast (can only be found in plants)
-Organelle where photosynthesis takes place.

23. Animal Cells vs. Plant cells

24. Animal Cells vs. Plant Cells

25. ANIMAL CELLS
• Unique parts of the animal cell
• Centriole – a feature of animal cells important for
coordinating cell division

26. PLANT CELLS
• Unique parts of the plant cell
• Cell wall – a feature of plants cells that functions like stiff
lattice-like wall which helps plant cells maintain their
structure and shape
• Chloroplast – a feature of plant cells that allows plants to do
photosynthesis and make their own glucose from sunlight,
water and carbon dioxide

27. EXERCISE 4: CARBOHYDRATE
SEARCH

28. Carbohydrates
• Large biological molecules
• Simple sugars, such as glucose, are the
monomers of complex carbohydrates.

29. • In Food science – polysaccharides are starch
and fiber.
• Polysaccharides are complex carbohydrates.
Starch and fiber are complex carbohydrates.
• Mono and di saccharides are simple
carbohydrate. Sugar is a simple carbohydrate.
• Simple carbohydrates are digested faster and
give you quick energy.

30. FOOD SAMPLE COLOR SIMPLE OR COMPLEX
1. Flour Dark blue-black comples
2. Sugar Brown tan simple
3. Apple Brown tan simple
4. Potato Dark blue-black complex
5. Bread Dark blue-black complex
6. Honey brown-tan simple
7. Vanilla wafer dark, blue-black complex
8. Marsmallow (inside) brown-tan simple
9. Banana dark, blue-black (green)
Brown-tan (ripe)
complex
simple
*These are the desired results of the experiment however, it may
vary upon groups since after putting iodine solution, the color will
not be evident and may take a long while; this might be confusing
(e.g. banana).
• Brown –tan (after putting iodine)= simple carbohydrate; foods
with sugars usually
• Dark, blue-black (after putting iodine) = complex carbohydrate;
foods with/rich in starch and fiber