Download Chapter One: What is Plant Biology?

Chapter One: What is
Plant Biology?
Introduction
 Plants make up more than 98% of total
biomass on Earth
 They produce oxygen, produce food for all
living things, and remove large amounts of
CO2 from atmosphere
 Life would not exist without plants
 If all plants on Earth were wiped out, the
oxygen in our atmosphere would run out
within 11 years
Introduction
 Plants belong to Kingdom Plantae
 Multicellular eukaryotes
 Cell walls made of cellulose
 Carry out photosynthesis using green
pigments chlorophyll a and b
 Include trees, shrubs, grasses, mosses, and
ferns
 Most are autotrophs
Plant Survival Needs
 Because plants are stationary, living on land
can be challenging
 Plants must have:
 Sunlight (photosynthesis)
 Water and Minerals (photosynthesis and
growth)
 Gas exchange (bring in oxygen, dispose of
CO2)
 Transport of water and nutrients
Early Plants
 The first plants evolved from an organism
much like the multicellular green algae
living today.
 Green algae are protists not plants
 DNA sequences show that plants came from
these green algaes
 Oldest plant fossils ~ 450 mya
 Similar to today’s mosses
 Simple and grew in damp places
Divisions
 Four main groups:
 Bryophytes (mosses and relatives)
 Seedless Vascular Plants (ferns and relatives)
 Cone-bearing plants (gymnosperms)
 Flowering plants (angiosperms)
 Groups based on three important features:
 Water-conducting tissues?
 Seeds?
 Flowers?
Relationship of Humans
with their Environment
 Human and Animal Dependence on Plants
Oxygen production
Food products
Lumber, paper, clothing
Coal, oil
Methane gas from decomposed plants and
animal manures
Gasohol
Plants and the Future
 Cultivation of food plants
 Use of plants in cleaning polluted water
 Algae and space exploration
 Identification and preservation of medicinal
plants
Botany as a Science
 Botany: the study of plants
 Science: “a search for knowledge of the
natural world”
 Botanists: scientists who study plants
 Scientific Method:
 Observations and testing hypotheses
 Principles and theories
Botany as a Science
 Hypothesis: tentative, unproven explanation
for something that has been observed
 Controlled experiment: an experiment in
which only one variable is changed
 Variable: specific aspect of an experiment
 Independent: variable that you control
 Dependent: variable that changes in response to
independent (what you measure)
Microscopes
 Anton van Leeuwenhoek (1632-1723)
Development of primitive microscopes
First to describe bacteria, sperm, and
other microbes
 Primitive microscopes
Led to the discovery of plant cells (1665)
Botanical Disciplines
 Plant Anatomy: internal structure of plants
Marcello Malpighi (1628-1694)
Discovered various tissues in stems
and roots
Nehemiah Grew (1628-1711)
Structure of wood
Botanical Disciplines
 Plant Physiology: plant function
J. B. van Helmont (1577-1644)
Flemish physician and chemist
Famous willow branch experiment
Botanical Disciplines
 Plant Taxonomy: identifying, naming, and
classifying plants
 Oldest branch of plant study
 Carolus Linnaeus (1707-1778)
Wrote Species Plantarum (1753)
 Pteridologists: study ferns
 Bryologists: study mosses and other similar
plants
Botanical Disciplines
 Plant Geography: how and why plants are
distributed, 19th century
Sir Joseph Hooker
Charles Darwin
Botanical Disciplines
 Plant Ecology: interactions of plants with
one another and with their environments
Rachel Carson
Wrote Silent Spring (1962)
Increased public awareness of ecology
with her publication
Botanical Disciplines
 Plant Morphology: form and structure of
plants, 19th century
Botanical Disciplines
 Other related sciences:
Genetics: heredity studied with plants,
plant breeding for crops, genetic
engineering for food, medicine, etc.
Cell biology: study of cell structure and
function
Electron microscopy
Economic botany and ethnobotany:
practical uses of plants and plant
products (herbal medicine)