Lecture 1: Intro to Plants, Intro to Science
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Transcript of Lecture 1: Intro to Plants, Intro to Science
Pyrola asarifoliahttp://www.pbase.com/rodg/western_washington_native_plants
Plants are: BeautifulUnusualComplexDiverseThey feed us!They are the lungs of the earthThey have charted the course of human settlement on earth (grasses).They put a roof over our headsMany have greatly impacted history
People and Plants
We affect each other. – how?»We can’t live without them!»They exchange CO2 for O2 – mitigates greenhouse
effect.»We destroy, pollute their habitat, causing extinction»They can destroy habitat, harming our economy –
invasive plants!!»We can alter the course of their evolution, through:
–Gm crops, conservation genetics, selective breeding
THE PROCESS OF SCIENCE
The word science is derived from a Latin verb meaning “to know”
» Science is a way of knowing» Science developed from our curiosity about
ourselves and the world around us
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 Hypothesis?
Tentative, but untested explanations» Ex. Tree height is limited by N availability
Make predictions that can be tested» Predictions written as “If [hypothesis], then……”
statements » Ex. If tree height is limited by N availability, then
adding N to the soil should cause the 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 - the thing (variable)
studied, manipulated or tested» Dependent variable - the thing(s) affected by
the independent variable. What you measure!
» Controlled Variables - All other things (variables) that you try to hold constant
Experiments of classical design
Individuals studied divided into two groups» Experimental group
–exposed to the independent variable » Control group
–exposed to the identical conditions as the experimental group, but not be exposed to the independent variable
The Process of Science in Action
• Biology in the news: From npr.org Harvard scientists found people who ate bacon at
least five times a week were 59% more likely to develop bladder cancer than those who never did. Chemicals called nitrosamines and heterocyclic amines may be to blame. The study appears in the American Journal of Clinical Nutrition. The Harvard team studied data on nearly 136,000 people. The participants were followed for up to 22 years, during which time 808 developed bladder cancer.
However, the research is far from definitive. The researchers also found people who ate bacon and other processed meats frequently were also more likely to smoke and to take in more fat and fewer vitamins. They were also less likely to exercise. Dr Emma Knight, science information manager at Cancer Research UK, said: "The link between diet and cancer is complex and difficult to unravel but we know that eating lots of red and processed meat can increase our risk of some types of cancer. "More research is needed before we can say for sure whether or not eating bacon in particular affects bladder cancer risk. "For now, our advice remains to eat a balanced diet that is low in fat, processed and red meat, and rich in vegetables, fruit and fibre." More than 10,000 people a year are diagnosed with bladder cancer in the UK
How does science really work in today’s world?
Exhaustive literature search + observations hypothesis
Prediction Write a proposal, design experiment Get money $$$$$ Revise proposal based on $$$ Experiment/collect data Statistics Write manuscript of results Publish or perish
Hypothesis vs. Theory vs. Law?
A fact leads to a law, eventually.What is a law?Phenomenon that is invariable – is
always trueBased entirely on observations, no need
for testingExample of a law?
What happens if all of our experiments fail to negate our hypothesis?
What if workers in other parts of the community, county, state, country, or world also fail to negate your hypothesis?
Theory A well-tested explanation of the observations (never been proven false.) 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.
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– • Collect water & minerals from soil• Anchor plant• Store food (carbos from photosynthesis)
to be used for flowering & fruiting• 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
Support, transport Some photosynthesis Two types of shoots
1. Vegetative – leaves only
2. Reproductive – produces flowers Two parts of stem:
1. Node – point of leaf attachment
2. Internode – stem segments between nodes
Two types of buds
1. Terminal bud – contains a shoot apical meristem; shoot growth is concentrated here
2. Axillary buds – in angle (axil) between leaf & branch, contain meristem with potential to become a vegetative shoot. Mostly dormant.
Apical dominance = the presence of an apical bud inhibits the growth of axillary buds.
-remove or depress apical bud, axillary buds begin to grow.
Modified Shoots (stems):
Stolons – above-ground runners
Rhizomes – below-ground runners
Bulbs – swollen underground shoots
Tubers – swollen rhizomes
Asexual, vegetative propagation
Stores food for later growth
Leaf types:
Simple leaf = undivided but may be lobed, serrated, cleft, etc.Compound leaf = divided into distinct units called leaflets
Four types of leaf arrangement:
1. Acaulescent – leaves arranged in a basal rosette, not attached to a stem.
2. Alternate – leaves borne single at each node along the stem
3. Opposite – leaves borne across from each other at the same node
4. Whorled – 3 or more leaves arising from the same node.