Plant Physiology is a subdiscipline of Science

Science: a methodical approach to the acquisition of knowledge

What is the methodical approach that makes it science?

Observation - measure in the metric system
Question - be curious!
Hypothesis - convert question to a falsifiable educated guess to be tested
Prediction - if hypothesis is true then certain event should take place
      if hypothesis is false then that event should not take place
      [then the dependent variable will respond]
      when I manipulate some factor [the independent variable]
Experiment - a manipulated condition (treatment) is observed
      next to unmanipulated condition (control)
      with replication in each condition!
Analysis - mean, standard deviation, other statistical testing...
      allow 5% for error due to chance alone
Decision - hypothesis is rejected or not (note: not ever proven)

Theory: a hypothesis never rejected in spite of thorough testing from every perspective

A quick review of the Metric System

MetricEnglish (many base units omitted!)
lengthmeterinch foot yard mile nautical mile furlong fathom
weightgramounce pound ton long ton
volumelitert T C pt qt gal bbl (which one?)
temp°C 0-100°F 32-212
many others in plant physiology!


prefixesmultiplierdescriptorsci notation
kilo-1000one thousand103
centi-1/100one hundredth10-2
milli-1/1,000one thousandth10-3
micro-1/1,000,000one millionth10-6
nano-1/1,000,000,000one billionth10-9
some others in plant physiology!

Plant Physiology is a subdiscipline of Biology

Biology - the study of life

What is Life?

Notice how these properties of life involve organismal functions.
Physiology is the study of function.
So what is a plant in biology?

Plant Physiology is a subdiscipline of Botany

Botany = Plant Biology = Plant Science

the study of plant life

Biological Classification

Kingdom Plantae (not Bacteria, Archaea, Protista, Chromista, Rhodophyta, Fungi, or Animalia)

Division Anthophyta (historically less focus on: Chlorophyta, Bryophyta, Pteridophyta, Coniferophyta, etc.)

Class Dicotyledonae (less focus on Monocotyledonae)



Genus----------------------------> Latin

Species epithet--------------> Binomial

Variety (cultivar)           Lactuca sativa 'Tango'

Biological Phylogeny

Plants are a clade

Plant Physiology: the study of normal functions of plants