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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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