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Learning Module in Science 7
Lesson 1: Micro Operation
INTRODUCTION
In this lesson, you will learn about the microscope, its parts and their uses, as well as
its proper care. You will also learn how a microscope works. These are essential learning
skills for effective laboratory work in studying microorganisms and specimens too small to
be seen by the unaided eye.
How to join the VSMART?
Install VSMART application or visit the website:
school.vsmart.ph
Log in your given username and password
Go to your scheduled lesson
OBJECTIVES:
At the end of the lesson, you will be able to:
Identify parts of the microscope (S7LT-IIa); and
Focus specimens using the compound microscope (S7LT-IIb-2).
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MODULE 1: Parts of The Compound Microscope
How Does a Microscope Work?
Compare these images from what our naked eyes can see. What can you observe?
The Compound Microscope
Microscopes are instruments that can magnify or enlarge the image of objects that are
otherwise too small to be seen by unaided eyes. There are many different kinds of microscope
but the type that is most extensively used in biology laboratory work is the compound
microscope.
The compound microscope is said to be a light microscope because it makes use of
light. Light from a source is directed by the mirror through the transparent specimen and
reaches the eye of the viewer where the image of the object is projected.
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Parts of the Compound Microscope
For effective use and proper care of the compound microscope, you should be familiar
with its parts. The different parts of a compound microscope may be grouped into
illuminating, magnifying and mechanical parts.
Illuminating Parts
These parts provide light to the microscope.
Mirror – an adjustable part held by the mirror fork or
rack, it is used for collecting and reflecting light
through the object lenses, and into the eye. It is flat on
one side and concave on the other. Generally, the
concave side is used with natural daylight whereas the
flat side is used for artificial light.
Condenser – found beneath the stage, it concentrates
the reflected light from the mirror to the object being
examined.
Iris Diaphragm – a thin structure with an adjustable
opening located at the mount of condenser, it is used
to regulate the intensity of light that enters the
condenser.
Magnifying Parts
These parts make the object look larger. As far as the function of the microscope is
concerned, they play the most important role.
Eyepiece or Ocular – it is a detachable short cylinder located
on top of the draw tube through which one views the specimen.
The number “10X” that appears at its top side refers to its
magnifying power. It may have a pointer for pointing specific
parts of the specimen.
Objectives – two objective lenses are usually attached to the
revolving nosepiece magnifying power is indicated at their sides.
There are two kinds of objective according to their magnifying
power.
a. Low Power Objective (LPO) – it is the shorter tube with large
lens opening and with lower magnifying power for observing
the general outline and locating various parts of the
specimen.
b. High Power Objective (HPO) – it is the longer tube with
smaller opening and higher magnifying power for studying
the detailed parts of the specimen.
Activity: Micro-Operation
For Test I (numbers 1 to 5), read each statement carefully. Choose TRUE if the statement
is correct, if false, change the underlined word with the correct answer.
1) Eyepiece is a detachable short cylinder located on top of the draw tube through which
one views the specimen.
a. True b. False
2) The number “10X” that appears at its top side refers to its illuminating power.
a. True b. False
3) Mirror is flat on one side and concave on the other side.
a. True b. False
4) Iris Diaphragm a thick structure with an adjustable opening located at the mount of
condenser, it is used to regulate the intensity of light that enters the condenser.
a. True b. False
5) The two kinds of objective lenses are high power objective and high power objective.
a. True b. False
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For Test II (numbers 6 to 10) identify which part of the microscope is being described in
each statement.
6) It is used for collecting and reflecting light through
the object, lenses and into the eye.
_____________________
7) It concentrates the reflected light from the object
being examined. ________________________
8) It is the longer tube with smaller opening and
higher magnifying power for studying the detailed
parts of the specimen. _____________________
9) It is used to regulate the intensity of light that
enters the condenser. _______________________
10) It is the shorter tube with large lens opening and
with lower magnifying power for observing the
general outline and locating various parts of the
specimen. ________________________
MODULE 2: Mechanical Parts of A Compound Microscope
What are the mechanical parts of a compound microscope?
The Mechanical Parts of a Compound
Microscope
These are the parts that support the microscope
and the object being examined.
Stage - This is the platform on which the slide
containing the specimen is held in place with a pair
of stage clips. It has a central opening that allows
light from below to pass through the specimen. In
some microscopes, a mechanical stage is provided
to facilitate the movement of the specimen by
means of a screw.
Arm - it is the curved handle of the microscope that
connects the base and the body tube. It serves to
support the optical mechanism.
Substage - Found below the stage, it holds the condenser above and the iris diaphragm
below.
Inclination joint - This is a movable hinge that attaches the frame of the microscope
to the base. It is used for tilting or inclining the microscope when necessary.
Revolving nosepiece - Attached to the base of the body tube, it holds and facilitates
shifting of objective lenses.
Dust shield - Located above the revolving nosepiece, it keeps off the dust from the
objective lenses.
Pillar - This refers to the post or upward extension of the base to which the arm is
attached.
Base - This is the stable structure on which the microscope firmly rests.
Draw tube - A smaller cylinder, it is attached to the upper part of the body tube and
holds
Body tube - A hollow cylinder, it attaches the draw tube to the microscope and serves
as passageway of light from the object to the ocular.
Adjustment knobs - Consisting of two pairs of knobs, they are used for lowering or
raising the body tube.
a) Coarse adjustment knob - It is the larger knob used for faster movement when
focusing the LPO.
b) Fine adjustment knob - It is the smaller knob for slow or little movement when
focusing.
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Activity: Parts and Figures
1. Label the partys of a compound microscope.
2. Differentiate coarse and fine adjustment knobs.
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
3. Differentiate low and high power objectives.
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
MODULE 3: Operation of The Microscope
Operation of the Microscope
In order to view a specimen clearly, you must first learn how to properly operate a
microscope. Here are the steps on how to use a microscope as well as how to compute for
its magnifying power.
Obtain proper lighting
1. Set the LPO in line with the eyepiece or ocular.
2. Open the iris diaphragm.
3. Adjust the mirror so it faces the light source; then set it at an angle to reflect light
towards the stage.
Focus a specimen under the LPO
1. Place the mounted specimen on the stage. Hold it in place using the stage clips.
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2. While looking at the side of the microscope, carefully turn clockwise the coarse adjustment
screw to lower the body tube until the LPO is about 1 mm from the specimen.
3. With both eyes open, look with one eye through the ocular.
4. Slowly turn the coarse adjustment knob counterclockwise to raise the objective until the
image of the object comes into clear focus.
5. Bring the image into sharper focus by turning to either direction the fine adjustment
screw.
6. If no image appears, check the exact position of the mounted specimen and repeat the
process.
Activity 1: Step by Step
Test I. Arrange the steps in obtaining proper lighting. Write numbers 1-3.
______ Set the LPO in line with the eyepiece or ocular.
______ Open the iris diaphragm.
______ Adjust the mirror so it faces the light source; then set it at an angle to reflect
light towards the stage.
Test II. Arrange the steps in focusing a specimen under LPO. Write numbers 1-6.
_____ Place the mounted specimen on the stage. Hold it in place using the stage clips.
_____ While looking at the side of the microscope, carefully turn clockwise the coarse
adjustment screw to lower the body tube until the LPO is about 1 mm from the
specimen.
_____ With both eyes open, look with one eye through the ocular.
_____ Slowly turn the coarse adjustment knob counterclockwise to raise the objective
until the image of the object comes into clear focus.
_____ Bring the image into sharper focus by turning to either direction the fine
adjustment screw.
_____ If no image appears, check the exact position of the mounted specimen and repeat
the process.
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Lesson 2: The Levels of Life
INTRODUCTION
This lesson is intended to draw attention to the different levels of biological
organization. You will also discover the importance of the cell in the life of an organism. This
lesson will also help learn the differences between plant and animal cells.
How to join the VSMART?
Install VSMART application or visit the website:
school.vsmart.ph
Log in your given username and password
Go to your scheduled lesson
OBJECTIVES:
At the end of this lesson, should be able to:
describe the different levels of biological organization from cell to biosphere (S7LT-IIc-
3);
differentiate plant and animal cells according to presence or absence of certain
organelles (S7LT-IId-4); and
explain why the cell is considered the basic structural and functional unit of all
organisms (S7LT-IIe-S).
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MODULE 1: Levels Of Biological Organization
What do you think made up an individual?
No individual lives alone. An individual belongs to
a family, and different families belong to a community so
they all need to help each other maintain peace,
cleanliness, and harmony in their community. If the
different communities work together, this would be
contributing to the success of the country. If a country is
made up of different communities, and community with
different families, what do think made up an individual?
Matter is basically made up of atoms which are
organized into different elements as have learned in your
chemistry class. These elements react and combined to
form compounds. These compounds maybe simple, complex, or more complex but they
remain to be compounds. Note that nonliving things stop at this level.
However, in with living things, from the compound level, they become organized to form
cells, the basic unit of life. This is the smallest entity that can be called living. From this level,
the other living levels are organized.
How are the body parts of an organism so organized that they work together in
harmony? The illustrate on shows the organization of an organism's body parts at
various levels. It starts from the cell, the basic unit of structure and function of all living
things.
Activity: Body System
Below are the different body systems of an organism. From the choices below, choose
one example of organ/tissue that compose the following body systems.
Nerves
Spinal cord
Lungs
Esophagus
Brain
Nostrils
Blood
Heart
Stomach
Neurons
Alveoli
Trachea
Mouth
Blood vessels
Liver
Pancreas
Respiratory Circulatory Digestive Nervous System
System System System
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LEVELS OF BIOLOGICAL ORGANIZATION
What are the levels of biological organization?
The different levels of organization are composed of: atoms, cells, tissues, organs,
organ systems, organisms, population, community, ecosystems or biomes, and the
biosphere.
The Cell Level
The cell is the basic unit of structure and function of a living things. There is nothing
smaller than a cell that one can considered as living. This is the simplest level in which
structures can be organized into a living condition.
One-celled organisms or unicellular organisms like bacteria and most protists are
organized only at the cellular level. Each cell performs the tasks of carrying out all life
processes. These processes are done by the different parts of the cells called organelles. Each
organelle performs specific Job for the organism as a whole. All the tasks are divided and
take place inside each cell.
On the other hand, multicellular organisms like
humans, plants, or animals are more complex. These
organisms exhibit a more complex organization in order to
function. Nevertheless, their basic level of organization is
still the cellular level. Unlike unicellular organisms, their
cells exhibit specializations. It means that they have
different types of cells specialized to do a certain function.
For example, human body contains nerve cells for
transmission of nerve impulses, muscle cells for
contraction, bone cells for support, epithelial cells for
protection, and many more types of cells, each of which
performs a specialized function.
The Tissue Level
A tissue is a group of cells that have the same structure
and performs specific function. These cells are organized to
perform a more complex function. For example, a single red
blood cell could accomplish very little task. Other examples of
tissues that can be found in humans and animals are:
epithelial tissue for protection, connective, and tissue for
support, vascular tissue for transport, muscular tissue for
contraction and movement, and nervous tissue for
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transmission of nerve impulses to regulate all other body functions. Plants also have different
tissues that function for protection, storage, and food making.
The Organ Level
Several tissues functioning together as a unit to perform a specific complex function is
called organ. For example, stomach is an organ. The stomach is consists of several tissues.
All these tissues perform together for digestion of food. If any of these tissues failed to do
their specific task, the organ would stop functioning.
Plants have organs, tin. The ants for anchorage and absorption of water, the stems for
support and conduction of food and water, leaves for photosynthesis, flowers for production
of seeds, fruits for protection of seeds, and seeds for reproduction of new plants.
The Organ System Level
A group of organs working together to
perform a specific function is referred as organ
system. The human digestive system is an example
of an organ system. In order to perform digestion
and absorption of nutrients, several organs are
needed. Among these are the mouth, pharynx,
esophagus, stomach, intestines, and rectum.
Other organ systems in the human body are the
circulatory system, respiratory system, excretory
system, integumentary system, skeletal system,
reproductive system, nervous system, muscular
system, and endocrine system.
Organism Level
The next level of biological organization is the organism itself. Organism is made up of
one cell (unicellular) or organ systems (multicellular
Population Level
Group of organisms of a certain species that operate or work together in a certain area
is referred as population.
Community Level
Different populations interacting and living together in a given area forms a
community. Thus, all the organisms thriving in a forest make up the forest community.
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Biome/ Ecosystem Level
The totality of the different communities in a
specific geographical area, including the biotic and
abiotic factors forms the biome or ecosystem. A desert
is considered a biome. This is because it consists of a
sand dune community, an oasis community, a sand
plain community, and several others. Other biomes
include tropical rainforest, savannas, temperate
deciduous forests, chaparral temperate evergreen,
temperate coniferous forest, tropical monsoon forest,
and tundra.
Biosphere Level
Earth includes all living things is the biosphere.
This is made up of all the biomes and kinds of
ecosystems on Earth. The biosphere is the highest level
in biological organization.
Activity: Level Up and Down
Identify the level of biological organization being described in each statement.
________________ 1. A group of cells that have the same structure and performs specific
function
________________ 2. A group of organs working together to perform a specific function
________________ 3. The basic unit of structure and function of a living things
________________ 4. Several tissues functioning together as a unit to perform a specific
complex function
________________ 5. Group of organisms of a certain species that operate or work together in
a certain area is referred as population
________________ 6. Different populations interacting and living together in a given area
________________ 7. An individual made up of one cell (if unicellular) or organ systems (if
multicellular) that possess all the characteristics of the species to which
it belongs
________________ 8. This is made up of all the biomes and kinds of ecosystems on Earth
MODULE 2: Cells in Plants and Animals
What is the difference between plant and animal cells?
Both plant and animal cells have the same three main parts: cell membrane,
cytoplasm, and nucleus. However, they differ in a number of ways.
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Plant and animal cells differ greatly in size and shape.
Plant cells are surrounded by an outer protective cell wall, which is absent in animal
cells. The cell wall is relatively rigid, while the cell membrane is elastic. The rigidity of
the cell wall permits plant cells to maintain their shape.
Vacuoles in animal cells are small and vary in their
uses: some are for storage of food or water, others are
for excretion of waste materials. In plant cells, the
initial many small vacuoles combine to form bigger
vacuoles.
Eventually, the mature plant cells may have but a
single large, centrally located vacuole with the
cytoplasm confined at their sides. The large plant
vacuoles function for intracellular digestion, space
filling, and control of cell turgor.
Located in the cytoplasm just outside the nucleus of animal cells and some protists is the
centrosome, which is absent in plant cells. The centrosome plays an important role in
animal cell division.
The rounded, oval, or irregularly shaped bodies called plastids are absent in animal cells.
The most well-known plastids in plant cells are the green-pigmented or chlorophyll-
bearing chloroplasts. Another kind of plastid called chromoplastid contains two types of
pigments: carotenes (cream, white, yellow, orange, and red colors) and xanthophylls
(bright yellow and brown colors).
Activity: Attendance Check
Compare the plant and animal cells and complete the table below. Submit your work
to your teacher.
Parts of the Cell Plant Cell Animal Cell
Cell membrane
Cell wall
Centrosome
Chloroplasts
Endoplasmic reticulum
Golgi apparatus
Lysosome
Mitochindria
Nucleus
Ribosome
Vacuoles
Cells in Plants and Animals
The Organelles of the Cell
The cell is the basic structural unit of life. All living organisms, regardless of size and
form are composed of cells. Some organisms are made up of only one cell. For example, a
paramecium or a bacterium has only one cell. However, others have trillions of cells just like
humans.
Plant and animal cells have the three main parts, namely:
nucleus (plural: nuclei), the part of the cell where the genetic material is found;
cell membrane, which protectively envelops the cytoplasm; and
cytoplasm the part where the main life activities occur.
Nucleus
The nucleus is covered by a membrane, the nuclear
membrane. It consists of a double layer of fats and proteins and
associated short chains of sugars. However, it differs from the
cell membrane in that it has many holes or pores.
Inside the nucleus is a fluid, the nuclear sap (also called
nucleoplasm or karyoplasm). Several structures are suspended
in this fluid. One of these is the nucleolus (plural, nucleoli). Some
cells have two or more nucleoli. Besides the nucleoli, the nucleus
also contains chromosomes. These are long thread-like
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structures, which are made up of molecules of protein and DNA. The chromosomes are
responsible for the transmission of traits from one generation to the next. The DNA makes
up the genes.
Cell Membrane
The cell membrane consists of a double layer
of fats and proteins. It is elastic. The elasticity of the
cell membrane is due to the structure of protein
molecules; they are relatively long molecules, which
can easily be folded.
The cell membrane is also differentially
permeable. This means that it permits some
substances to pass through readily, others slowly,
and still others not at all. For instance, gases and
alcohol pass through the cell membrane rapidly. Water passes through it fast but not as fast
as gases and alcohol. The large molecules of proteins, fats, and carbohydrates do not pass
through it at all. They have to be broken down or digested first before they can pass through
the cell membrane.
Cytoplasm
Early cytologists referred to the cytoplasm as "complex fluid." Cytoplasm is the gel-sol
solution that can be found inside the cell membrane but outside the nucleus. The gel-sol
consistency of the cytoplasm is significant for the regulated transport of materials inside the
cell. It consists of go to water, organic compounds, inorganic compounds, and some gases.
Organelles and other specialized structures of the cell are suspended in cytoplasm.
Suspended in this fluid are different kinds of structures called organelles which enable the
cell to perform the metabolic life processes.
Organelles in the cytoplasm
Mitochondrion
A mitochondrion (plural: mitochondria) consists of an
outer membrane, an inner membrane that is folded inward,
and a liquid that fills the cavity. The liquid and membranes of
a mitochondrion contain respiratory enzymes. These
enzymes promotes chemical reactions that lead to the release
of energy in stored food, making it available for use by the
cell.
Lysosomes
Lysosomes are another kind of organelle in the cytoplasm.
They are structurally similar to the mitochondria except that
their inner walls are not thrown into folds.
Golgi bodies
Also found in the cytoplasm are the Golgi bodies. A Golgi
body consists of short bands of very fine parallel cavities or
flat sacs. They are rich in fatty material. They are largely
found in cells that secrete certain substances, or those that
make up gland cells.
Endoplasmic Reticulum
The electron microscope has revealed that the cytoplasm
has an intricate system of very fine tubes or cavities, the
endoplasmic reticulum. ft is a network of pathways through
which materials flow to the different parts of the cytoplasm.
The endoplasmic reticulum consists of a double layer of fats and proteins.
The endoplasmic reticulum may be smcoth or rough. The rough endoplasmic reticulum
(RER) is associated with tiny spherical structures called ribosomes. Other ribosomes float
in the cytoplasm. Ribosomes are rich in RNA molecules. They are the sites where protein
molecules are formed. The smooth endoplasmic reticulum (SER) has no ribosomes. ft is a
site for lipid and detoxification of drugs.
Activity: Who Am I?
Read the statements carfully and examine the puzzle
1. Guess the word being describe in each sentence.
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MODULE 3: Cell: Basic Unit of All Organisms
What is the importance of studying the cell?
The Cell Theory
Theodor Schwann, a zoologist, and Matthias Schleiden, a botanist, formulated the cell
theory based on their separate studies on animals and plants respectively. At present the cell
theory is summarized as follows:
All living things are made up of one or more cells.
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Cells are the basic structural unit of living things.
All cells come from pre- existing cells.
Cell Size
Cell Size vary from one type to another. The approximate size of an object that an
unaided human eye can perceive is about 0.1 mm. Cells smaller than 0.1 mm can be made
visible under a light microscope. The most powerful light compound microscope that have a
magnification of at least 2,000x can magnify bacteria but not viruses. To see organisms
smaller than 500 nm, one needs an electron microscope that utilizes a high voltage beam of
electrons to magnify objects.
Specialized Structures of the Cell
There are other structures in the cell that also perform specific functions. This includes
the ribosomes, microtubules, and microfilaments. The latter two are structures forming the
cytoskeleton, the centrioles, and the cilia and flagella.
Ribosomes
Ribosome are structures in the cell made up of rRNA and proteins. They are granular
structures scattered in the cytoplasm or attached to rough endoplasmic reticulum.
Ribosomes are made up of two subunits, a smaller subunit and a larger subunit. This is the
site for protein synthesis or production of proteins.
Centrioles
Centrioles are organized micro tubular structures. They are found in animal cells.
Centrioles are activated during cell division where they initiate the formation and movement
of spindle fibers during cell division.
Cytoskeleton
The cytoskeleton forms the structural framework of the cytoplasm of a cell. It is made
up of a network of microtubules, microfilaments, and intermediate filaments (larger
microfilaments). It holds the structural parts of the cell in place by serving as anchorage for
the cell parts. It also is important for the motility of the different structures and substances
of the cell in varied metabolic processes like cell division.
Microtubules
Microtubules are microscopic tubular structures made up of protein tubulin.
Microtubules are the structural units of several cell structures such as cytoskeleton,
centrioles, cilia, and flagella.
Microfilaments
Microfilaments are microscopic fibrous structures made up of proteins like actin. They
are smaller than the microtubules and are very important for the motility of the cell as well
as for cellular structure.
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Cilia and Flagella
Cilia and flagella are locomotory structures of some cells that are both made up of
microtubules. Cilia are shorter in length as compared to flagella
Activity: What’s with the Cells?
Read each statement carefully. Choose TRUE if the underlined word is correct, if false, give
the correct answer
______________ 1. The cell theory states that all living things are made up of one or more cells.
______________ 2. Organs are the basic structural unit of living things.
______________ 3. All cells come from pre-existing tissues.
______________ 4. Cell size vary from one type to another.
______________ 5. Ribosomes are structures in the cell made up of rRNA and proteins.
______________ 6. Centrioles are organized microtubular structures that are found in plant
cells.
______________ 7. Centrtioles are activated during cell division where they initiate the
formation and movement of spindle fibers during cell division.
______________ 8. The cytoskeleton forms the structural framework of the cytoplasm of a cell.
______________ 9. The cytoplasm is made up of a framework of microtubules, microfilaments
and intermediate filaments.
______________ 10. Microfilaments are microscopic fibrous structure made up of proteins like
actin.
MODULE 4: Diversity of Cells
How do the cells differ in every organism?
The parts of the cell work interdependently with each other for the cell to perform its
function and maintain its living condition. Now, you will differentiate the cells of vaned
organisms.
Prokaryotes vs. Eukaryotes
Living organisms can be classified as prokaryotes or eukaryotes. Prokaryotic organisms
lack nucleus and membrane-bound organelles like mitochondria and chloroplast in their
cells. They are usually one-celled organisms such as bacteria.
On the other hand, eukaryotic organisms have cells with true nucleus and membrane-
bound organelles. These are unicellular organisms such as protists, and multicellular
organisms such as animals, plants, and fungi. The following table shows the differences
between prokaryotes and eukaryotes:
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Look at the table below. Examine the difference between prokaryotic and eukaryotic cells.
Points of Difference Prokaryotes Eukaryotes
Number of cells Unicellular Unicellular and
multicellular
Organelles Absent Present
Nuclear membrane Absent Present
Nucleus Absent but has a
nucleoid region where the
DNA is located
Present
Chemical composition of
chromosomes
DNA DNA and histones
Number of chromosomes One Two or more
Variation in Structure and Form of Cells
Below are several kinds of plant cells. They vary greatly in size and shape. Does the
particular structure of a cell have any usefulness to the plant?
The closely arranged regular epidermal leaf cells serve to protect the underlying parts,
while the kidney-shaped cells are so arranged to form breathing pores called stomata
(singular, stoma). The elongated, thickened stem cells are for the passage of food and water.
The root hairs are outgrowths of epidermal cells, which increase the absorbing capacity of
roots. Pollen grains are small and light; some are with hooks and wings, which are structural
adaptations for different agents of pollination.
Below are different kinds of animal cells. As with plant cells, their structures are related
to the functions they perform. For instance, the skin cells are flat and arranged into a sheet;
these are characteristics that are best for covering or lining a surface. The cells lining our
windpipe have hair-like projections called cilia. They help in removing dust particles from the
air we inhale. The white blood cells have a very elastic cell membrane that can engulf
infectious agents that enter the body.
_
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Activity: In the Land of the Living
Drag and Drop
1. Which are examples of plant and animal cells?
Plant Cells Animal Cells
______________________ ___________________________
______________________ ___________________________
______________________ ___________________________
Stoma Pollen grains
Cilia in trachea Cells in stem
White blood cells Skin cells
