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"

Communicate results

Test the hypothesis

Develop one or more testable hypotheses

Ask Questions about what you see

Observe the Natural World

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 re-evaluate 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

Tissues

Organs

Systems

Muscle cell

Muscle tissue

Heart

Circulatory system

Parenchyma cell

Dermal tissue

Leaves

Shoot system

Three organs: Roots, stems, leaves

1. Roots–

• Covered with root hairs – increased surface area for absorption

Modified Roots –

Prop roots

Sweet Potato – storage root

Aerial strangler roots

Pneumatophores

Buttress roots

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 buds1. Terminal bud –

2. Axillary buds – in angle (axil) between leaf & branch, contain meristem with potential to become a vegetative shoot. Mostly dormant.

Apical dominance =

-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_Info.htm

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