This is for Quarter 2 SHS

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UNIFYING THEMES IN LIFE
Different Characteristics of
Living Things
1. Living Things are made up of
cell
2. Living things metabolize
 Anabolism
 Catabolism
3. Living things grow and
develop
4. Living things respond to
stimuli
5. Living things interact
6. Living things reproduce
7. Living things adapt and
evolve
8. Living things have organize
structure
Ten Themes that Unify in the
Study of Life
Theme 1: Biological Systems
A biological system is a complex
network of biologically relevant
entities. Biological organization spans
several scales and are determined
based different structures depending
on what the system is. Examples of
biological systems at the macro scale
are populations of organisms
Interaction of organism with each
other and with the nonliving
environment put the system in
ecosystem.
Theme 2: High Degree of
Organization
New properties emerge at each level in
the biological hierarchy The hierarchy
of life unfolds as follows: biosphere –
ecosystem – community – population
– organism organ system – organ –
tissue – cell – organelle – molecule -
atom. With each step upward from
atoms, new properties emerge as a

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result of interactions among
components at the lower levels.
 Atoms- building blocks of
matter
 Molecules- are combination
of atoms formed through
chemical bonding
 Cell- is the basic unit of life
 Tissue- are group of cells
performing specific function
 Organs- formed from cluster
and layers of tissues carrying
specific function
 Organ System- group of
organs functioning together
in a system
 Organism- are the individuals
in the population functioning
and performing
characteristics
 Population- refers to the
group f organism of the same
species interacting together
 Community- consist of
different populations living
and sharing a particular
habitat
 Ecosystem- composed of
communities interacting with
non-living components of
environment
 Biosphere- compose of all
ecosystem
Theme 3: Structure and Function
Structure and function are also related
in living things. What something does
in an organism is directly related to its
shape or form.
Structure and function are related at
the level of chemicals in cells. For
example, membrane channels and
enzymes are both proteins, but they
have very different structures and
functions. A channel is a protein
molecule that extends through the
membrane, or outer layer, of a cell. It
has a structure like a tube that allows
specific chemicals to pass into and out
of a cell. Enzymes are protein

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molecules that make chemical
processes possible in living things.
These proteins have shapes that allow
them to attach to only certain
chemicals and then cause the
chemicals to react with each other.
The relationship between structure and
function is apparent in the entire
organism and the physiological
systems that serve them. The structure
determines function, function reflects
structure
The relationship between structure and
function is apparent in the entire
organism and the physiological
systems that serve them. The
structure determines function,
function reflects structure
Theme 4: Reproduction and
Inheritance
Sexual reproduction is the union of
male and female gametes to form a
fertilized egg, or zygote. The resulting
offspring inherit one half of their traits
from each parent. The process where
haploid sex cells are created from
diploid parents is called meiosis, and it
occurs only in the reproductive organs.
In humans, an egg cell from the
mother fuses with a sperm cell from
the father that results in a fertilized cell
containing a combination of DNA from
both parents. The inherited DNA
directs the transformation of the
fertilized egg into a person with
his/her own eye color, facial features,
and other characteristics.
Theme 5: Life requires Energy
Transfer and Transformation
Energy is the ability to do work, where
work is done when a force moves an
object. While the sun provides energy
for our entire planet, the sun's energy
must be transformed into more usable
forms for living organisms.
All organisms lose energy in form of
heat, an ecosystem cannot recycle
energy. Life on Earth depends on a

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continuous supply of energy from the
sun.
Theme 6 Organisms Interact with
other Organisms and the Physical
Environment
In an ecosystem, each organism
interacts continuously with its
environment, which includes both
other organisms and physical factors.
The leaves of a tree, for example,
absorb light from the sun, take in
carbon dioxide from the air, and
release oxygen to the air.
“No man is an island.” This saying is
also true for organisms in an
ecosystem. No organism exists in
isolation. Individual organisms live
together in an ecosystem and depend
on one another. In fact, they have
many different types of interactions
with each other, and many of these
interactions are critical for their
survival.
Theme 7 Organisms must maintain
Homeostasis to Survive in Diverse
Environment
Homeostasis is the maintenance of
constant internal conditions in an
organism. Homeostasis is important
because cells function best within a
limited range of conditions.
Temperature, blood sugar, acidity, and
other conditions must be controlled.
Breakdowns in homeostasis are often
life threatening.
Homeostasis is usually maintained
through a process called negative
feedback. In negative feedback, a
change in a system causes a response
that tends to return that system to its
original state.
The ability of mammals and birds to
regulate body temperature is another
example of homeostasis or “steady-
state”. Different mechanisms enable
organisms to regulate their internal

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environment despite changes in their
external environment
Theme 8 Evolution and Adaptation
Evolution is the change in living
things over time. More specifically,
evolution is a change in the genetic
makeup of a subgroup, or population,
of a species. The concept of evolution
links observations from all levels of
biology, from cells to the biosphere. A
wide range of scientific evidence,
including the fossil record and genetic
comparisons of species, shows that
evolution is continuing today.
One-way evolution occurs is through
natural selection of adaptations. In
natural selection, a genetic, or
inherited, trait helps some individuals
of a species survive and reproduce
more successfully than other
individuals in a particular environment.
An inherited trait that gives an
advantage to individual organisms and
is passed on to future generations is
an adaptation.
Evolution is a unifying theme of
biology because it accounts for both
the diversity and the similarities, or the
unity, of life. All of the species alive
now are the result of billions of years
of evolution and adaptation to the
environment. How? Natural selection
of genetic traits can lead to the
evolution of a new species. In the end,
this genetic diversity is responsible for
the diversity of life on Earth.
Theme 9 Scientific Inquiry
In scientific inquiry, scientists make
observations (collect data) and use
inductive reasoning to draw a general
conclusion, which can be developed
into a testable hypothesis. Deductive
reasoning makes predictions that can
be used to test hypotheses: If a
hypothesis is correct, and we test it,
then we can expect the predictions to
come true. Hypotheses must be

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testable and falsifiable; science can
address neither the possibility of
supernatural phenomena nor the
validity of religious beliefs.
Through science, humans learn about
the solution to various problems, the
scientific method is able to give
direction and pace for every inquiry,
and technology produced machinery
to lengthen the life of perishable
goods. Technology applies scientific
knowledge in new ways.
Theme 10 Biology and Society
The relationship of science to society
becomes clearer when we add
technology to the picture. Though
science and technology sometimes
employ similar inquiry patterns, their
basic goals differ. The goal of science
is to understand natural phenomena.
In contrast, technology generally
applies scientific knowledge for some
specific purpose. Biologists and other
scientists usually speak of
“discoveries,” while engineers and
other technologists more usually speak
of “inventions.” And the beneficiaries
of those inventions include scientists,
who put new technology to work in
their research. Thus, science and
technology are interdependent.
Modern biology is changing humans’
everyday lives. New findings about the
DNA affect medicine and agriculture.
Research on the nervous system is
improving the treatment of certain
mental illnesses. The result of stem cell
research, animal cloning,
environmental issues, genetically
modified crops or new ways to treat
diseases show the impact of biology.

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