Weber State University       Department of Botany

BTNY LS1203 - Plant  Biology

Attributes of Life

1.  The Cellular Basis of Life

“The key attribute of life is a boundary, a container that separates inside from outside and prevents desirable molecules from floating away, while keeping undesirable ones at bay.” – Julius Rebek

Cell Theory 
the cell is the smallest living unit
all organisms are composed of one or more cells
cells come from pre-existing cells
==> cells are fundamentally alike in their basic chemistry and processes

two types of cells:  prokaryotic and eukaryotic

2.  Metabolism

includes all of the chemical reactions of an organism  
most focus is on energy conversion reactions (respiration, photosynthesis), digestion, and assimilation

3.  Growth

irreversible increase in size:  increase in cell number, increase in cell volume 
limited by an organism's genetic heritage and environmental factors

4.  Reproduction

produce descendants:  sexual or asexual reproduction 
genetic variation in offspring from mutations, genetic mixing

5.  Response to Stimuli

on microscopic and macroscopic scales 
rapid and slow responses

6.  Movement

cellular level to whole organism 
plant movements in response to stimuli or part of developmental processes

7.  Adaptation to the Environment

organisms have features (structural, physiological, etc.) that enable a particular organism to do 2-6 in a particular environment at a particular time 
    variation in a population of organisms 
    at least some of that variation is inherited 
    differential survival and reproduction 
    → over time, evolution by natural selection occurs as the population changes and becomes adapted to the environment of a specific place at a specific time 
    example:  Saguaro cactus.  This cactus does fine in the hot desert biome of Tucson, but it is not well adapted for our cold desert biome.

Return to Botany 1203 Home Page.

Return to Botany 1203 Syllabus.

Return to Harley Home.

8 January 2011