Characteristics of Life
I. Origin of the Environment
A. Lithosphere (crust) of Planets ex Earth,
1. Planets are products of star formation
2. nebula cloud of gas and dust collapsed
due to gravity
a. Sun forms at center where large
amount of H fuses to produce
energy
b. material along edges cooled and
condensed to form the planets,
moons, meteors, asteroids, comets
3. volcanic eruptions add to Earth’s crust
B. Atmosphere
1. Today’s atmosphere is nitrogen(78%) and
oxygen(21%). Early atmosphere was
methane, ammonia, and carbon dioxide.
2. Volcanoes released water vapor and
other gases from the Earth’s interior
3. Photosynthesis used CO2 and released
O2. (Ozone forms later.)
C. Hydrosphere
1. As Earth cooled, water vapor condensed to form clouds. Precipitation filled the oceans and lake basins.
2. Erosion of rock and soil added salts and minerals to the water.
II. What are living things? (Unity of Life)
A. Living things are organisms which :
1. are made of cells:
a. one celled =unicellular
b. more than one cell=multicellular
2. use energy from
a. sunlight
b. other organisms
c. chemical compounds in the
environment
3. can adapt to their surroundings due to
physical features
4. can react to changes in their
surroundings = response
5. grow and change or develop during
their lifetimes
6. can produce more organisms of their own
kind
B. All living organisms need:
1. energy
obtained from food or the environment
a. autotrophs make their own food
using solar energy or chemical
energy from the environment
b. heterotrophs obtain food energy
from other organisms
2. water
a. used by plants to make food
b. is important solvent for
chemical reactions of life
c. transports substances for organisms
3. living space
must provide all the organisms needs:
food, water, air, and safe shelter
4. proper temperature
a. cold-blooded : body temp changes
with the outside, so organism must
adjust themselves
b. warm-blooded: constant body temp
c. homeostasis: maintain constant
internal conditions. Ex: body temp,
blood sugar levels
5. Air:
a. most organisms need oxygen:
aerobic
b. there are some organism (small in
size!) which are anaerobic
III. Life Processes
A. Living organisms carry out life processes (metabolism = these life processes in an organism)
1. Nutrition = process of obtaining food
which is used for growth and energy
a. ingestion: take in food
b. digestion= breaking food down into
a usable form
c. egestion: get rid of
undigested/unusable food
2. respiration= the release of chemical energy stored in food, most organisms need oxygen to do this; a chemical process
3. excretion = removing gaseous and liquid waste resulting from life activities
4. transport = internal process of carrying nutrients and necessary products to all parts of the organism and removing wastes products
5. regulation
a. control and coordination of life
processes
b. response to stimuli = respond to
changes in the organism’s internal
or external environment
6. growth & development
a. an increase in cell size or number of cells
b. change in appearance
7. reproduction = making new organisms of the same kind, necessary for survival of the species BUT not for the individual
IV. Taxonomy (Diversity of Life)
A. Living organisms are organized into groups for easier study
1. classified by similar physical
characteristics
ex. multicellular, photosynthetic
2. details of internal and external
structures are considered
ex animals with a backbone,
insects with ten legs
3. classification system is arranged from general (Kingdom) to specific (species)
Kingdom (largest category)
Phylum
Class
Order
Family
Genus
Species (most specific
category)
B. There are SIX kingdoms of organisms
1. Archaebacteria –
a. one- celled, no nucleus
b. Primitive bacteria, found at the bottom of the ocean at or near volcanic vents
c. Chemosynthetic
2. Moneran-
a. one- celled, no nucleus,
b. some may be photosynthetic
c. Ex. bacteria, bluegreen algae
d. Used for yogurt, cheese, decompose dead organisms
3. Protista-
a. one- celled , with a nucleus,
b. plant or animal like
c. Ex. amoeba, paramecium, algae
d. Used for food for some
organisms, some produce oxygen for life
4. Fungus
a. multicelled with nucleus
b. heterotroph, non-green plant
c. absorbs food from environment
or other organisms
d. Ex. mold, yeast, mushrooms
e. Used for food production,
decompose dead organisms
5. Plantae-
a. multicelled with nucleus
b. autotroph, chlorophyll for
photosynthesis, make their own food and oxygen
c. Ex. grass, geranium, tree, moss
6. Animalia-
a. multicelled with nucleus
b. heterotroph, must obtain food from plants and other animals
c. Ex. human, cats, birds, fish,
snails, Insects, worms
*** VIRUSES ??? Where do they fit in?
a. do not have a cell structure!!
b. survive by “taking over” live cells
which enables them to reproduce
They are considered non-living because:
do not grow, take in food or produce wastes
c. a piece of nucleic acid covered
with an outer protein shell; shapes may vary
d. are NOT classified with living
organisms in the Kingdoms
C. Every living organism is assigned a:
Kingdom, Phylum, Class, Order, Family, Genus,species.
1. Living organisms are identified by
genus and species = scientific name
Ex. House cat = Felis domesticus
Lion = Felis leo
Tiger= Felis tigres
· only same species can
mate and produce offspring
2.Humans are:
Kingdom- animal large #
Phylum- chordata general
Class- mammalia
Order- primates
Family- hominidae
Genus- Homo specific
species- sapien small #
IV. Classification Schemes: dichotomous
keys
A. Series of statements
a. based on visible physical
characteristics you can observe
ex. cell structure, number of legs,
b. used to identify an organism by name
B. Classification
a. must use observable PHYSICAL
properties
b. do NOT use COLOR !
c. do NOT use what it does:
“does it fly?” “does it swim?”
d. ask a question:
“Does it have four legs?”
“ Does it have wings?”
“Does it have fins?”
“Does it have hair?”