BISC 102 Chapter Notes - Chapter 1: Organism, Archaea, Carl Linnaeus

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Chapter 1: Biology and the Tree of Life
1.1 - What does it mean to say that something is alive?
Organism: a lifeform; a living entity made up of one or more cells; most biologists agree that
organisms share five fundamental characteristics:
Cells: membrane-bound units; make up organisms
Information - encoded information (genes) and responding to information coming in
from the environment
Energy - acquire and use energy
Theory: an explanation for a very general class of phenomena or observations that is
supported by a wide body of evidence
1.2 - Life is Cellular
Early discoveries:
Robert Hooke devised the first crude microscope and noticed compartments that he
named “cells” in bark tissue
Leeuwenhoek then developed more powerful microscopes that added evidence of
All organisms are made of cells, from the smallest organisms (bacteria) to some of the largest
(e.g. sequoia trees)
Cell theory: all organisms are made of cells, and all cells come from preexisting cells
That is, cells are produced from the growth and division of preexisting cells
Shown by Pasteur in his experiment involving nutrient broths and either swan-
neck flasks (prevented cells from entering the flask) and straight-necked flasks
(allowed cells to enter the flask from the air)
The first cells arose from nonlife through chemical evolution
1.3 - Life Evolves
Darwin and Wallace proposed that all species are connected by common ancestry
This is paralleled in human biology in the way all cells in the body are the result of
division and are linked by common lineage
Darwin and Wallace’s theory:
1. Species are related by common ancestry
2. A species’ characteristics can be modified from generation to generation
(i.e. species are related to one another and can change through time)
Natural selection: explains how evolution occurs; two conditions of natural selection:
1. Characteristics that are heritable: meaning trains that can be passed on to offspring
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