1-1 Understanding Life
Life on Mars?
1984 small rock found in Antarctica
a meteorite-originated from Mars
scientists found microfossils of bacterialike
was there life on Mars at one time - maybe
is there life on Mars now - no
Life on Earth,
Characteristics of Living Things
Yes - many diverse living things
Biology = study of living things
Organisms = living things
signs of life are characteristics
chemical substances
one or more cells
use energy
definite form and size
limited life span
growth
respond to changes in the environment
reproduce
groups change over time
1-2 Life Processes
Homeostasis
Nutrition
Transport
Respiration
Synthesis
Growth
Excretion
Regulation
Reproduction
Metabolism
The following slides
will explain each life process that is listed on the left of this slide.
Homeostasis
Condition of a constant internal environment
Nutrition
Materials from environment used by organisms
nutrients needed for
energy, growth, repair, maintenance
Two basic types of nutrition:
photosynthesis - organism makes own food
eating other animals
ingestion - taking in of food
digestion - breakdown of complex food to simple form
Transport
Substances enter and leave cell
Circulatory system in complex organisms
blood carries nutrients and oxygen to cells and carries wastes away from cells
Plants have a special system of roots, branches and leaves
Respiration
Process of releasing chemical energy
complex series of chemical reactions
aerobic respiration - with oxygen
anaerobic respiration - without oxygen
Synthesis
Combination of simple substances chemically to form more complex substances
In animals the products of digestion
materials become part of the organisms
assimilation - incorporation of materials into the organism’s body
Growth
Process by which organisms increase in size
single cell - growth is just increase in size
multicellular - growth is an increase in size and the number of cells
cellular specialization - different cells become specialized for different functions
plants grow indefinitely
Regulation
All activities that help homeostasis
animals - nervous and endocrine systems
nerve network and impulses
hormones - chemical into bloodstream
changes in internal and external environments
plants - do not have nerves but do have hormones
Reproduction
Process of reproduction of new organisms of their own kind
necessary for continuance of that kind of organism
Two types:
asexual - single individual reproduces offspring
sexual - two parents, offspring are not identical to either parent
Metabolism
All chemical reactions of an organism
building
breakdown
continuous release of energy
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