Transcript Biol 100: Lecture 1 - Tacoma Community College

Lecture 1: Intro to Plants, Intro
to Science
Why do we love plants? What makes them so special?
Plants are:
People and Plants

We affect each other. – how?
»We can’t live without them!
».
».
»They can destroy habitat, harming our economy –
invasive plants!!
»We can alter the course of their evolution, through:
–Gm crops, conservation genetics, selective
breeding
Plants are sources of
food
 paper
 fibers
 Medicine
 Chocolate
 Sugar
 vanilla
 cinnamon

•pepper
•wood
•cotton
•linen
•roses
•paper
•oxygen
THE PROCESS OF SCIENCE

The word science is derived from a Latin verb
meaning “to know”
» Science is a way of knowing
».
The Process of Science:
"The Scientific Method"
Observe the Natural
World
Ask Questions about what you see
Develop on e or more testable hypotheses
Test the hypothesis
Communicate results
What’s a Scientific Question?
 Scientific
Questions are….
What’s a Hypothesis?

Tentative, but untested explanations
» Ex.

Make predictions that can be tested
» Predictions written as “If [hypothesis], then……”
statements
» .tree to grow taller
How do you test a Hypothesis?


Via controlled experiments or pertinent observations
» All variables must be controlled
Kinds of variables:
» Independent variable –
» Dependent variable –
» Controlled Variables - All other things
(variables) that you try to hold constant
Experiments of classical design

Individuals studied divided into two groups
» Experimental group
» Control group
– exposed to the identical conditions as the
experimental group, but not be exposed to the
independent variable
What happens if all of our experiments fail to
disprove our hypothesis?
 What if workers in other parts of the
community, county, state, country, or world
also fail to disprove your hypothesis?

Theory

We arrive at theories by scientific method
To Prove or Not to Prove
Experimentation can either support or reject a
hypothesis.
 Experimentation can never prove a hypothesis
100% correct. – why?


After each each experiment we need to reevaluate our results and observations to either
make changes in our hypothesis or more likely
design a new experiment.
Which end of a plant is up?
Cells
Muscle cell
Tissues
Muscle tissue
Parenchyma cell
Dermal tissue
Organs
Heart
Leaves
Systems
Circulatory
system
Shoot
system
Three organs: Roots, stems, leaves
Roots–
1.
•
Covered with root hairs – increased
surface area for absorption
Sweet Potato –
storage root
Modified
Aerial strangler roots
Roots –
Prop roots
Buttress roots
Pneumatophores
2. Stems/shoots


Two types of shoots
1. Vegetative –
2. Reproductive –
Two parts of stem:
1. Node – point of leaf attachment
2. Internode – stem segments between
nodes
Two types of buds
1.
Terminal bud –
Axillary buds – in angle (axil) between leaf
& branch, contain meristem with potential to
become a vegetative shoot. Mostly
dormant.
Apical dominance =
2.
-remove or depress apical bud, axillary buds
begin to grow.
Modified Shoots (stems):

Stolons –

Rhizomes –

Bulbs – swollen
underground shoots
Tubers – swollen rhizomes

Asexual,
vegetative
propagation
Stores food
for later
growth
3. Leaves – main photosynthesis organs
http://www.knotweed.co.uk/japknot_Inf
Modified
leaves

Compound, doubly
compound – why??
Modified
leaves
Leaf types:
Simple leaf =
Compound leaf = divided into distinct units called
leaflets
Four types of leaf arrangement:
1. Acaulescent –
2. Alternate –
3. Opposite – leaves borne across from each
other at the same node
4. Whorled – 3 or more leaves arising from the
same node.
3Each male flower part is called a stamen.
The stamen is composed of:
1. Filament –
2. Anther – a collection of pollen sacs that
sits on top of the filament.
Each female part is called a pistil.
Pistil = the female reproductive organ, consisting of:
1. Stigma –
2. Style –
3. Ovary – the base of the pistil, contains the
ovules. (Mature ovules are seeds and mature ovary
is the fruit)
More terms!!!
Complete flower =
Incomplete flower = lacks one of the above
parts
Fruit types
Fruit =
*the primary function of a fruit is seed dispersal