Basic Characteristics of all Living Things
1. Living things contain nucleic acids, proteins, carbohydrates, and lipids.
2. Living things are composed of cells.
3. Living things grow and reproduce.
4. Living things use energy and raw materials.
a. Metabolism: All chemical reactions that occur within the cells of living things.
5. Living things respond to their environment.
6. Living things maintain homeostasis.
7. Populations of living things evolve and have adaptive traits.
a. Adaptive traits help reproduce and survive in a natural environment.
1. Make careful observations and ask a question about the observations.
2. Develop a testable hypothesis (possible explanation) as a possible answer to your
3. Make a prediction based on your hypothesis and test it with a controlled
a. Controlled experiment: Involves a control group and an experimental group.
4. Draw a conclusion based on the results of the experiment.
Inductive Reasoning: Facts are accumulated through observation until the sheer weight of
the evidence allows some logical general statement to be made.
(From Psyc: Reasoning from the bottom up starting with specific facts and trying to
develop a general principle)
Deductive Reasoning: Begins with a general statement that leads logically to one or more
deductions, or conclusions.
(From Psyc: Reasoning from the top down from general principles to a conclusion
about a specific case.)
Epidemiological Studies: Researchers look at patterns that occur within large
1. Is the information consistent with information from other sources?
2. How reliable is the source of the information?
3. Was the information obtained through proper scientific procedures?
4. Were experimental results interpreted correctly?
5. Are there other possible explanations for the results?
A group of cells of similar type that work together to serve a common function.
- Epithelial tissue
o Covers body surfaces, lines body cavities and organs, and forms glands.
- Connective tissue
o Serves as storage site for fat, plays an important in immunity, and provides the
body and its organs with protection and support.
- Muscle tissue
o Responsible for the body movement and for movement of substances through the
- Nervous tissue
o Conducts nerve impulses from one of the body to another.
- Free surface
o Specialized in protection, secretion or absorption
- Basement membrane
o Noncellular layer that binds the epithelial cells to underlying connective tissue
and helps the epithelial tissue resist stretching.
3 basic shapes
- Squamous epithelium
o Made up of flattened, or scale-like, cells.
Form lining in the blood vessels or lungs, where O or 2O diffu2e easily.
Reduces friction also.
- Cuboidal epithelium
o Made up of cube-shaped cells
Found in many glands and in the lining of kidneys Provide protection and
are specialized in secretion and absorption.
- Columnar epithelium
o Consists of elongated, column-shaped cells Specialized for absorption and
o Have numerous small, fingerlike folds Increasing the surface area for
absorption & eases the passage of food
Found in the small intestine
Simple epithelium (Squamous, Cuboidal or Columnar) (Single layer of cells)
Stratified epithelium (Squamous, Cuboidal or Columnar) (Multiple layers of cells)
o Protective role many layers provide additional thickness making it more
difficult for molecules to pass through.
Gland: Epithelial tissue that secretes a product.
2 Exocrine Gland: Secretes their products into ducts leading to body surfaces, cavities, or
Endocrine Gland: Lack ducts and secrete their products, hormones, into spaces just
outside the cells, into the bloodstream.
Common role to bind (tendons and ligaments) and support (cartilage and bones)
Also specialized in transport (blood) and energy storage (adipose tissue)
Connective tissue made up of
- Matrix: Consists of protein fibers and noncellular material called ground substance.
o Ground Substance: May be solid (bone), fluid (blood), or gelatinous (cartilage).
Matrix contains 3 types of protein fibers
- Collagen fibers
o Strong and ropelike and can withstand pulling because of great tensile strength.
- Elastic fibers
o Contains random coils and can stretch and recoil like a spring.
o Great elasticity (skin, lungs, blood vessels)
- Reticular fibers
o Thin strands of collagen that branch extensively, forming interconnecting
networks suitable for supporting soft tissue. (Liver and spleen)
All protein fibers produced by fibroblasts.
- Repair tears in body tissues
- Connective tissue proper (loose and dense)
o Loose connective tissue: Contains many cells but has fewer and more lossely
woven fibers than matrix of dense connective tissue.
Areolar connective tissue: Functions as a universal packing material between
other tissue. (Ex. Between muscles)
Adipose tissue: Contains cells that are specialized in fat storage. (Fat acts as
insulation and shock absorber for certain organs)
o Dense connective tissue: Forms strong bands because of its large amounts of
tightly woven fibers. (Found in ligaments join bone to bone; tendons join
muscle to bone, and dermis layer of skin below the epidermis)
- Specialized connective tissue (cartilage, bone and blood)
Tough but flexible Cushioning between certain bones, and helps maintain
structure of body parts. (Ears and nose)
Hyaline cartilage: Most abundant; provides support and flexibility.
(Found at the end of long bones, where it allows one bone to slide easily
over another nose, ribs, larynx and trachea)
Elastic cartilage: More flexible than hyaline cartilage because of the large
amounts of wavy elastic fibers in its matrix. (Found in the external ear)