Unit 1: Introduction to b1iology

• Biology is the scientific study of life or living things

• What does it mean to be “alive”?
• It seems very difficult to objectively define life in a simple sentence
• But, it can be recognized by main common xteristics shared by living
systems
• Living things:
• Are composed of one or more cells
• Are complex and highly organized
• Can respond to stimuli, grow, reproduce, etc.
• Transmit genetic information to their offspring
• Need the energy to accomplish work
• Can maintain relatively constant internal conditions (homeostasis)
• Are capable of evolutionary adaptation to the environment, etc.
The scientific method
• Biologists study about living things using a
scientific method that involves:-
• Asking questions
• Suggesting possible answers and
• Testing for the validity of the answer through
experiments
• Thi s scientif ic study f o l l o ws t he s t udy o f
structures and processes that we can verify
observe and measure, either directly or indirectly
with the help of tools and technology such as
microscope
 What relationships does Biology have with other
fields of natural sciences?

• The study of biology is a point of merging information
and tools from all natural sciences.
• For example information about naturally occurring
elements in living organisms, chemical bonding,
molecules, acids ,bases and other related things can be
studied using the tools and principles of chemistry.
• Other scientific concept like conversion of radiant
energy into organic molecules by photosynthesis is
studied with the knowledge of chemistry and Physics


 1.2 Why do we study Biology?

• Human beings have an inborn curiosity about the natural world that
leads them to study about living organisms and their habitats.
• Studying biology helps to understand how living things work, how they
function and interact with the environment.
• Biology touches our everyday life in many ways.
• For example, biologists have discovered drugs that are used to treat
different human diseases.
• Many biologists are working on problems that critically affect our lives,
such as
• how our animals and plants body work,
• how ecosystems work,
• how advancements in genetics and cell biology are transforming to
medicine and agriculture,
• as well as the use of forensics biology to investigate crime,

THE SCIENTIFIC METHOD
•What is the scientific method?

•What are the steps of the scientific method?

•Does the scientific method only work in

science class?
 The
Scientific
Method
The Steps to Success
 1.3. The Scientific Method

• Biology is a science of inquiry.
• What comes to your mind when you hear the word science?
• Biologists are always curious about why things happen or how things
happen.
• By asking questions and seeking science-based responses known as the
scientific method, they come up with new theories to explain new findings.
• The scientific method involves a series of steps that guide scientists
through such scientific investigations.
• Biologists study the living world by posing questions about it. The general
steps of the Scientific methods are:








Observation

• The scientific study begins with
careful observations (often a
problem to solve) that leads to
a question.
• The observations can be made
either directly (e.g. using your
sense organs) or indirectly
using scientific tools such as
microscopes.

Asking Questions

• The observations usually lead
the scientist to ask questions
(inquiry).
• You ask a question about what
you observe.
• State the problem or question

Do you remember the next
step?
Forming of a hypothesis

• A hypothesis is proposed
scientific explanations
(possible answers) for a set of
question (s).
• To solve a problem, one can
propose several hypotheses.
Scientific hypotheses should be
testable.

HYPOTHESIS
 Predictionbased on prior knowledge
 FORMAT: If x happens, then y happens,
because ________________.
 Example:
◦ Question: Will fertilizer affect how tall a
plant will grow?
◦ Hypothesis: IF fertilizer is added to a plant,
THEN, it will grow taller BECAUSE the plant
will gain more energy and nutrients to grow.
HYPOTHESIS PRACTICE
◦ What is the effect of a new drug on the number of offspring a mother
mouse has?
IF ________________ THEN ______________________
B/C__________________________________________
◦ What effect does temperature have on the number of chirps a cricket
produces?
◦ IF ________________ THEN ______________________
B/C__________________________________________
◦ What effect does 24 hours of light have on a plant?
◦ IF ________________ THEN ______________________
B/C__________________________________________
Testing the hypothesis

• Hypothesis can be tested through
experimentation.
• Any scientific experiment must
have the ability to be duplicated
because the “answer” the scientist
comes up with (whether it supports
or rejects the original hypothesis)
can’t become part of the scientific
knowledge unless other scientists
can perform the same experiment
and achieve the similar results.
• If a hypothesis is not supported by
experimental data, one can
propose a new hypothesis

Making conclusions
• Scientists consider their original
about the findings
hypotheses and ask whether they
could still be right in light of the
new information gathered during
the experiment.
• If so, the hypotheses can remain
as possible explanations for how
things work.
• If not, scientists reject the
hypotheses and try to come up
with alternate explanations (new
hypotheses) that can explain
w h at t h e y ’ v e se e n

Communicating the
findings
• When scientists complete
some work, they write a paper
that explains exactly what they
did and the results they
obtained.
• Then, they submit the paper to
a scientific journal in their field.
• In addition, the findings will be
printed in scientific journals
and assist teachers and
students in the field.

Example of a hypothesis
testing in everyday life

• Suppose you want to use your
torch (hand lamp) to find a
missing pen in your bedroom.
• When you switch the torch on, it
is not working.
• The following flow chart will
illustrate hypothesis testing for
a torch that doesn’t work.




 Think you can name all six
steps?

Communicate
the Results
Collect
Formulate
Observation/Research
Problem/Question
and
Experiment
Conclusion
Analyze
a Hypothesis
Results
 The Scientific Method

Test you knowledge by

visiting the Scientific Scenarios
and see if you can identify
the steps of the scientific
method.
 1.4 . Tools of a Biologist

• Biologists use different types of tools in the

laboratory and field for scientific investigations.
• Some of the tools are used for measuring, some
are used for observation and some are used for
culturing microorganisms

1.4.1. Laboratory tools of biologist

Lab Equipment
Hand lens
• Most cells cannot be seen with the
naked eye.
• A hand lens has a higher
magnification than our naked eye.
• It consists of a convex lens fixed
within a circular metallic loop and is
attached to a metallic or wooden
handle.
• The main function of hand lens is to
provide an enlarged image of the
object placed under it.
• But hand lens is not sufficient to
observe the detail in cells.
• There is a need for providing high
magnifications tools such as
microscope.

The Microscope

• One of the most important tools of

the biologist is a microscope.
• A microscope is an instrument
used to study objects that are too
small to be seen with a naked eye.
• The microscope magnifies the
image of small objects making
them visible to the human eye.
• For example, microscopes are
used to observe the shape of
bacteria, fungi and parasites.
• There are several kinds of
microscopes.
• The major types are:
• light microscope and
• electron microscope


• A light microscope is called light
microscope because it uses a
beam of light to view specimens.
• There are two types of light
microscopes,
• Simple light microscope which
consists of a single lens while
• a compound light microscope
consists of two or more glass
lenses

• A compound light microscope is the • Electron microscopes on the
most common microscope used in other hand use a beam of
biology. electrons (instead of a beam of
• It consists of two lens systems (a light) and electromagnets
combination of lenses) to magnify (instead of glass lenses) to
the image of an object up to 2000x. enlarge the image of an object.
• Each lens has a different magnifying • These microscopes provide a
power. higher magnification than light
• A compound light microscope with a microscopes and are used for
single eyepiece is called monocular; observing extremely small micro
one with two eye-pieces is said to be -organisms such as viruses.


binocular


Glass slides and cover slips • Glass slides and cover slips: The
microscope slides are used to
support an specimens being
examined under the microscope.
• The cover slips are the small square
or circle shaped thin glass sheets
that are used to cover specimens on
the glass slide to protect from
further addition of any chemical or
dirt and it is also used to protect the
microscope and prevent the slide
from drying by locking the moisture.
• Cover slides provide better view
under the microscope.

 • Autoclave: is the equipment
Autoclave used to sterilize (kill micro-
organisms) different
biological samples.
• An autoclave sterilizes
contaminated materials
including culture media, and
bacterial spores by
exposing them to high
temperatures and highly
pressurized steam.

 • Incubator: is a device used to
Incubator maintain a specific
environment for culturing.
• An incubator is an instrument
that maintains the temperature
best suited for the growth of
different types of
microorganisms

 • Petri dishes: are flat dishes with
Petri dishes a matching cover of a slightly
larger diameter.
• They are available in glass and
plastic form.
• Petri dishes are used with
gelling culturing media, such as
agar, and placed in the
autoclave to sterilize it

 • Culture tubes: are available
Culture tubes
in a huge range of sizes,
shapes, materials, and so
on.
• They are used to culture
micro-organisms.
• Culture tubes may be used
with solid (gel) culturing
media or with liquid (broth)
culturing media, and then
placed in the autoclave for
sterilization.

Flasks
• Flasks: is an apparatus having a flat
bottom and a long narrow neck,
which allows easy mixing of the
solution without spilling out the
content .
• it is also used to gently heat the
content inside with a gentle swirling
motion of the flask .
• It is essentially a large-volume culture
tube that is used only with broth
media and flasks are used to produce
large populations of micro-organisms.
• They are available in a variety of
shapes and sizes.

 • Balance: is useful for making
Balance up solutions accurately,
weighing specimens, and so on

Dropper
• Dropper: A dropper consists
of a glass tube that has a
small opening at one end
and is attached to a vacuum
rubber bulb at the other end.
• A dropper is used when it is
required to control the
amount of solution being
added to a reaction.

Tongs
• Tongs are metallic scissors-
shaped laboratory
instruments.
• It is used to Lifting or
picking up hot objects such
as heated crucible, beakers,
dishes, or flasks.

 • Dissecting Tool Kit is used to
dissect animals such as frogs,
Dissecting Kits fetal pigs, mice, etc.
• It consists of all the necessary
tools required to carry out the
process of dissection such as a
catheter, groove probe, scalpel,
surgical scissors (straight and
curved), mayo scissors
(straight and curved),
dissecting forceps (with and
without teeth), dissecting pin,
etc.

 • Dissecting pan is
Dissecting pan equipment is used as a
pan on which the
specimen is kept while it
is being dissected to
study its internal organs.







 • Crucible is a small
Crucible container made up of
ceramic or metal which
is able to withstand high
temperatures, and
therefore, it is generally
used to melt elements


Beaker
• Beaker is a cylindrical
glass container used
for making up
solutions, holding hot
or cold water or ice
baths, and so on


 • Hotplate is useful for
Hotplate
heating solutions,
making up an agar
culturing medium,
and so on.


pH meter and • pH meter is used to
Thermometer measure the pH
(acidity or basicity) of
substances.
• Thermometer is an
instrument that
measures the
temperature of
substances.


 • Forceps are used to
Forceps hold or pick up small
objects.
• They are available in a
variety of shapes and
sizes.


 • A spatula is used for
Spatula mixing substances into a
solution, stirring the
solution, and scrapping
objects.
• It is shaped like a spoon


 • Wash bottles which are
Washing bottles mainly used to rinse
various laboratory
materials.
• Wash bottles are flexible
in nature that allows the
user to adjust the water
pressure as per the need
by squeezing the bottle
accordingly


Bunsen burner or
alcohol burner
• This apparatus
produces a single open
flame and it is used for
heating and
sterilization purposes
in the various
experiments
conducted in labs


 KNOW YOUR LAB
EQUIPMENT
 Study your notes and drawings on the lab equipment.
 This is so vital when performing labs and reading
procedure.
1.4.2. Field tools

 • Insect nets –It is insect
Insect nets collecting nets which is
composed of some sort of net
bag made of cloth or fine mesh
that is attached to a wire loop,
which is attached to a wooden
or metal pole.

 • Fishing net is a net used for
Fish net
fishing.
• Nets are devices made from
fibers woven in a grid-like
structure.
• Some fishing nets are also
called fish traps.
• Fishing nets are usually
meshes formed by tying a
relatively thin thread

 Microscope Notes
Let’s get to know the Microscope!
 1.5. The Light Microscope

• Most microscopes have several different powerful
lenses attached to them, allowing the viewer to inspect
the content at more than 100 times its actual size.
• Biology as modern science would not exist without the
microscope, and good microscopes are essential for
day-to-day activities for most biologists.
• In addition to their importance, microscopes are
extremely expensive, therefore it is very important to
know the function of all structures of microscope and
handle the device properly before we are using it in the
laboratory.

• When we observe an image under light
microscope, light rays are focused on to the
image on a microscope slide.
• This Light which transmitted through the
specimen is then focused by two types of lenses
known as eye and objective lens.
• The enlarged produced by these two lenses.
• A compound light microscope magnification is
the product of eye and objective lenses, ×10
eyepiece and ×40 objective, the total
magnification is ×400.

 1.5.1. The parts and function of the light
microscope

• Microscopes are generally made up of
structural parts for holding and supporting
the microscope and its components and the
optical parts which are used for
magnification and viewing of the specimen
images.
• This section define the parts of a microscope
and the functions they perform to enable the
visualization of specimens

Parts of microscope
 Eyepiece Eyepiece tube
• Eyepiece is the part found • Eyepiece tube is the
at the top of the eyepiece holder.
microscope and is used
to look through the • It carries the eyepiece
microscope. just above the objective
• It is also named as the lens.
ocular. • In some microscopes
• Its standard such as the binoculars,
magnification is 10x with the eyepiece tube is
an optional eyepiece flexible and can be
having magnifications rotated for maximum
from 5X to 30X.

 Objective lenses Arm
• Objective lenses are major • Arm is a holder
lenses that further magnify
the specimen at different connected to all
intensities with multiple components that
objective lenses.
• Mostly they have a function as a support for
magnification power of the microscope so that
• 4X- lower objective the microscope can be
• 10X.- middle objective
• 40X –higher objective used properly

• 100X – oil immersion


 Body tube Nose piece
•Body tube • Nose piece is
rotating mount
connects the that holds many
eyepiece to objective lenses..
It is movable
the objective hence it allows to
lenses.
change the
magnification.


 The Adjustment knobs
• The Adjustment knobs are knobs that are used to focus
the microscope.
• There are two types of adjustment knobs i.e. fine
adjustment knobs and coarse adjustment knobs.
• Fine adjustment: regulate the distance between object
and objective, to achieve the necessary sharpness.
• The fine focus moves the stage only minimally.
• Coarse adjustment: Brings specimen into general focus.
Coarse adjustment also moves the stage to adjust the
difference between the object and the objective.
• The function of the coarse focus is to capture the
exact distance roughly and quickly.


 Stage Stage clip
• Stage is the • Stage clip acts as
section in which a holder for the
the specimen is object plate and
placed for viewing

ensures that it
doesn’t fall out of
place accidentally

 Aperture Microscopic illuminator
• Aperture is a hole • Microscopic illuminator
on the microscope is the microscopes light
source, located at the
stage, through base.
which the • It is used instead of a
transmitted light mirror. It captures light
from the source from an external source
reaches the stage of a low voltage of about
100v.
Condensers Diaphragm
• Condensers are lenses that • Diaphragm is also known as
are used to collect and focus the iris. It is found under the
light from the illuminator into
the specimen. stage of the microscope and
• They are found under the its primary role is to control
stage next to the diaphragm the amount of light that
of the microscope. reaches the specimen.
• They play a major role in
ensuring clear sharp images • It’s an adjustable apparatus,
are produced with a high hence controlling the light
magnification of 400X and intensity and the size of the
above.

beam of light that gets to the
specimen.
 Base

•Base is the very bottom part.

Base serves to accommodate all
parts of the light microscope
1.5.2 Handling and using a light
microscope
 1. When carrying the microscope you must carry it with the ARM and the
BASE.
 2. The microscope must always be stored with the lowest powered objective
in place.
 3. When bringing an object into focus you must use the lowest powered
objective and the course adjustment.
 4. ONLY use the FINE adjustment on the highest powered objective.
 5. Lenses should only be cleaned with lens paper.
 6. The whole microscope must be kept away from the edge of the lab table.
1.6. General Laboratory Safety Rules
 Safety is the condition of being protected from harm or other
danger.
 Safety can also refer to the control of recognized hazards in order
to achieve an acceptable level of risk.
 Laboratory safety is important before we do any activities in the
laboratory:
working carefully in the laboratory,

dealing with minor problems before they become major

problems,
 keeping safety constantly in mind are some of the safety
Important general lab. safety rules
are
1) Following the instructions
2) Knowing the location of safety equipment
3) Dressing for laboratory
4) Never eat or drink in the lab
5) Never teste or sniff chemicals
6) Act responsibly in the laboratory
7) Cleaning the exp’t area and storing the waste properly
8) Handling the chemicals properly
9) Knowing what to do with laboratory accidents
10) All laboratory personnel should place emphasis on safety and
chemical hygiene at all times