Lec. 1
Introduction to Human Biology
1st Grade Students MLT Dept.
What Does Biology mean?
Biology: The study of life.
Greek origin:
Bio: Life
Logos: Study of
 Levels of biological organization:
– Atoms
– Molecules
– Subcellular organelles
– Cells
– Tissues*
– Organs*
– Organ systems*
– Organism: May consist of a single cell or a complex
multicellular organism.
* Level of organization not found in all organisms
Levels of organization beyond organism:
• Population: Group of organisms of the same species that
interact with one another.
• Community: Several different populations living together
in same area (e.g.: lake, forest, jungle).
• Ecosystem: Interactions of community with non-living
environment (air, water, soil).
• Ecosphere: All ecosystems on planet earth. Includes:
– Biosphere: All biological communities on earth.
– Atmosphere (air)
– Hydrosphere (water)
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Lec. 1
Introduction to Human Biology
1st Grade Students MLT Dept.
– Lithosphere (crust)
Common features of all organisms:
1. Cells: Basic structural and functional unit of life. Genetic information
contained in DNA.
2. Growth and Development:
• Growth: Occurs by an increase in cell size, cell number,
or both.
• Development: Changes that take place during an
organism’s life.
3. Energy use and metabolism:
• All organisms must take in and transform energy to do
work, to live.
• Metabolism: All chemical reactions and energy
transformations essential for growth, maintenance, and
reproduction.
. Regulation
• External environment may change, but internal
environment remains fairly constant.
5. Movement:
• Internal movement: Characteristic of all life.
• Locomotion: Self-propelled movement from point A to
point B. Not observed in all life forms.
6. Respond to environmental stimuli: Organisms respond to internal and
external changes (visual stimuli, temperature, light, sound, pressure, etc.).
7. Reproduction: Organisms come from other organisms. Reproduction
may be sexual or asexual.
8. Evolutionary adaptation: Populations, not individuals, “evolve” or
change over many generations so they can survive in a changing world.
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Lec. 1
Introduction to Human Biology
1st Grade Students MLT Dept.
Kingdom Prokaryotae:
Include Bacteria and Cyanobacteria Which they lack nucleus and
membrane bound organelles and the nuclear material are spreaded inside
the cytoplasm
Five Kingdoms of Living World:
2. Kingdom Protista:
• Eucaryotes (True nucleus):
– Have nuclear membrane around DNA.
– Have membrane bound organelles (mitochondria,
chloroplast, golgi, endoplasmic reticulum).
• Unicellular or simple multicellular.
• Most are larger and more complex than bacteria.
• Some have cell walls, others don’t.
• Some make their own food (phothosynthetic), others must
eat other organisms.
• Include: Protozoa, algae, slime molds.
Kingdom Protista: Eucaryotic Unicellular or Simple Multicellular
Organisms
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Lec. 1
Introduction to Human Biology
1st Grade Students MLT Dept.
Five Kingdoms (Continued):
3. Kingdom Fungi: The digestion is external (Outside the body)
• Most are multicellular.
• Eucaryotes:
– Have nuclear membrane around DNA.
– Have membrane bound organelles (mitochondria,
chloroplast, golgi, endoplasmic reticulum).
• Include: Mushrooms, yeasts, and molds.
Five Kingdoms (Continued):
4. Kingdom Plantae:
• Complex multicellular organisms.
• Cellulose cell walls.
• Eucaryotes: Have nuclear membrane around DNA and
membrane bound organelles.
• Autotrophs: Convert sunlight, water, and carbon dioxide
into food through photosynthesis.
• Include: Trees, flowering plants, and mosses.
Five Kingdoms (Continued):
5. Kingdom Animalia:
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Lec. 1
Introduction to Human Biology
1st Grade Students MLT Dept.
• Complex multicellular organisms.
• Lack cell walls.
• Eucaryotes: Have nuclear membrane around DNA and
membrane bound organelles.
• Heterotrophs: Obtain chemical energy from living
sources. Eat other organisms for nourishment.
• Include: Sponges, worms, insects, and vertebrates.
Classification of Biological Groups in life cycle
1. Producers or Autotrophs:
•
Self-nourishing organisms (plants, algae, etc.).
• Produce food from simple raw materials.
• Most carry out photosynthesis:
CO2 + H2O + Sunlight -----> Food + Oxygen
• Depend on nonproducers for carbon dioxide
2. Consumers
• Mainly animals.
• Heterotrophs that obtain food directly or indirectly from
producers.
• Carry out cellular respiration:
Food + Oxygen -----> CO2 + H2O + ENERGY
Gas exchange between producers and consumers helps maintain balance of
life-sustaining gases in atmosphere.
3. Decomposers:
• Some bacteria, fungi, and animals.
• Recycle nutrients by breaking down products and bodies
of dead organisms.
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Lec. 1
Introduction to Human Biology
1st Grade Students MLT Dept.
• Process is vital because makes nutrients available for use
by other organisms.
• All organisms interact with each other and the environment they live
in.
• Interactions between producers, consumers, and decomposers are
essential to maintain proper conditions for life on earth.
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