1.
Biology - two Greek words, “bios,” which means life, and “logos,” which means
knowledge or study.
2. Biology - is a natural science concerned with the study of life or living organisms.
3. Living thing - Anything which interacts with its environment uses energy and reproduces
4. Biologist - scientists who study living organisms.
3 main divisions of science
- zoology
- botany
- microbiology
These major divisions may be further subdivided into branches that often correlate with one
another.
Branches of biology being grouped into four scopes:
- diversity and evolution of organisms
- the structure of life
- physiology of organisms
- interactions of organisms
A. DIVERSITY AND EVOLUTION
BRANCHES DEFINITION
EVOLUTIONARY BIOLOGY ● studies processes and patterns of biological
evolution
MAMMALOGY ● studies all animals with “mammary glands” or
breasts
ORNITHOLOGY ● studies all species of birds
HERPETOLOGY ● studies amphibians and reptiles
PALEONTOLOGY ● studies “remains” or remnants of organisms in
the past
TAXONOMY ● studies identification, naming, and
classification of organisms
PHYLOGENETICS ● studies evolutionary relations among groups of
organisms
SYSTEMATICS ● studies the diversity of organisms and their
origins or evolution
BOTANY ● studies all plant species
ZOOLOGY ● studies all animal species
MICROBIOLOGY ● studies organisms that cannot be seen with the
naked eyes (microorganisms)
PARASITOLOGY ● studies parasites and their hosts
PHYCOLOGY ● studies all species of algae
BACTERIOLOGY ● studies bacteria
MYCOLOGY ● studies fungal species
B. STRUCTURE OF LIFE
BRANCHES DEFINITION
MOLECULAR BIOLOGY ● studies the structure and functions of
macromolecules and how they interact with one
another to maintain the functions of life.
CELL BIOLOGY ● studies cell structures, functions, and behaviors.
GENETICS ● studies the heredity and variation of organisms.
DEVELOPMENTAL ● studies the processes involved as an organism
BIOLOGY grows and develops.
C. Physiology of Organisms
BRANCHES DEFINITION
PHYSIOLOGY ● studies functions of parts and structures of
organisms
ANATOMY ● studies parts or structures, their position, and
location in the body of organisms
NEUROBIOLOGY ● studies the biology of the nervous system.
IMMUNOLOGY ● studies the structures and functions of the
immune system.
PATHOLOGY ● studies causes and effects of diseases and
injuries.
D. Interactions of Organisms
BRANCHES DEFINITION
ECOLOGY ● studies interactions among organisms and with
their environment.
ETHOLOGY ● studies animal behaviors in their natural
environment.
1. ALL LIVING THINGS HAVE CELLS
1. Cells are the basic functional unit of life / small box-like structures.
2. All living organisms are made up of cells.
3. Unicellular - made up of only one cell, e.g, bacteria, yeasts, and some protists.
4. Multicellular - made up of two or more cells, e.g, humans, animals, plants, some protists,
and most fungi are examples.
5. Acellular - organisms that don’t have cells, e.g, viruses(not living things)
*The cells of each organism can carry out specific functions necessary for the organism to stay
healthy and alive.
6. Sperm cells - have a tail for locomotion
7. Red blood cells - are disc-shaped cells to carry and transport oxygen in our blood.
2. ALL LIVING THINGS ARE ORGANIZED
Cells - First Level
Tissues - cells that are combined
Organs - tissues that are combined
Organ System - multiple organs in the body
Organism - organ systems that are combined
Population - same species that are placed in a specific area.
Community - different species that are placed in a specific area
Ecosystem - when an organism interacts with non-living things.
Biome - Rainforests, desert, ocean, coral reefs, etc.
Biosphere - the sum of all biomes and it is anywhere on our planet where life is supported
3. NUTRITION
Energy - the reason why organisms stay alive and able to reproduce
- To gain energy organisms have to feed on substances to get the nutrition that their
bodies need.
Nutrition - a process by which organisms acquire food
Autotrophs/Producers - can produce their own food e.g plants
Heterotrophs/Dependent - cannot produce their own food e.g humans, animals, non-green
plants, and some microorganisms
PHOTOSYNTHESIS - a process by which plants convert solar energy to usable energy of
carbs.
In the process, oxygen release into the atmosphere
Metabolism - a process which is a total of chemical processes involved in obtaining food,
converting food to chemical energy, and transforming energy into usable forms by cells
- All organisms undergo metabolism to maintain their life
4. RESPIRATION
Respiration - a process which the breakdown of food substances releases the energy
- To perform daily tasks, organisms require energy.
CELLULAR RESPIRATION - a process which organic compounds produced by plants are
converted into the chemical energy of ADENOSINE TRIPHOSPHATE (ATP)
ATP - for cells of the body to perform specific functions.
Waste products - water and CO2 are the substances that will be eliminated out of the body by
excretion
5. EXCRETION
waste materials - sweat, fecal matter, and urine/can cause if not eliminated.
Excretion - a process that eliminates wastes inside the body of organisms.
*If wastes are not eliminated they can cause harm and destroy the body’s homeostasis.
Plants - water is eliminated through the STOMATAL PORES of fruits and leaves.
Unicellular Organisms - through their cell membranes.
Humans - through the anus, lungs, kidneys, and skin.
6. HOMEOSTASIS
Homeostasis - internal steady-state/regulatory systems that function as check-and-balance
whether the body's internal conditions are within their normal ranges.
- body temperature
- blood pressure
- heart rate
- water content
- uptake of nutrients by our cells
7. REPRODUCTION
Reproduction - a process thru which organisms produce or perpetuate their kind
- by which genetic information is passed from one generation to the next.
Asexual reproduction - does not involve sex cells or gametes
Sexual reproduction - involve sex cells or gametes
8. GROWTH AND DEVELOPMENT
Biological growth - pertains to the permanent increase in size and volume by converting food
that we intake to become part of our body cells.
Intussusception - Living things exhibit growth from within the cells.
Accretion - Non-Living things grow by the external addition of substances.
E.g - growth of a pearl within a shell
Biological development - different from growth / It makes an organism more complex or even
changes its form.
E.g - when a caterpillar undergoes metamorphosis, it changes its form and turns into a
butterfly.
9. MOVEMENT
Movement - an action of an organism or part of an organism that causes a change of position or
place.
Locomotion - ability to move / same definition as movement
* Animals like corals and sponges cannot locomote, but they can move some parts of their
bodies.
* Plants can exhibit slow movements. For example, tendrils climb to foundations for support,
shoots bend towards the direction of light and the blooming of flowers.
* Non-living things can move, but their movement is dependent on external forces.
E.g - wind and water currents can move light objects.
10. SENSITIVITY
Stimuli - are non-living environmental factors such as light, pressure, temperature, chemical,
gravity, and others that greatly affect living things.
Tropism - reaction of one organism towards a stimulus.
Sensitivity, responsiveness, or irritability - an ability of organisms to sense and respond to a
stimulus
● One good example of sensitivity is the reaction of a Makahiya plant (Mimosa pudica).
When touched, it automatically closes its leaves.
● Another example is when a fly is attracted to the smell of food.
11. ADAPTATION
Adaptation - the ability of an organism to become suited to its environments.
Dinosaurs - became extinct because they failed to adapt to the environmental changes during
the Ice Age period.
● Living things need to adjust and adapt because the environment they live in constantly
changes.
● Birds migrate all the time in search of food and to escape harsh winter
12. ORGANISMS HAVE DNA
DNA - direct and control the rest of an organism’s characteristics, such as its organization,
metabolism, capacity to reproduce, growth and development, and adaptation.
- Unique to each organism
- most reliable means for scientists to identify species.
