Lecture 1: Intro to Plants, Intro to Science

Why do we love plants? What makes them so special?

Pyrola asarifolia shington_native_plants Plants are:  Beautiful  Unusual  Complex  Diverse  They feed us!  They are the lungs of the earth  They have charted the course of human settlement on earth (grasses).  They put a roof over our heads  Many have greatly impacted history

People and Plants l We affect each other. – how? »We can’t live without them! »They exchange CO 2 for O 2 – 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

Plants are sources l of food l of paper l of fibers l of medicines

Life without l chocolate l sugar l vanilla l cinnamon l pepper l wood l cotton l linen l roses l paper l oxygen

THE PROCESS OF SCIENCE l 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"

What’s a Scientific Question? l Scientific Questions are…. » Testable » Definable » Measurable

What’s a Hypothesis? l Tentative, but untested explanations »Ex. Tree height is limited by N availability l 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? l Via controlled experiments or pertinent observations »All variables must be controlled l 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 classica l design l 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.

l 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? l Exhaustive literature search + observations   hypothesis l Prediction l Write a proposal, design experiment l Get money $$$$$ l Revise proposal based on $$$ l Experiment/collect data l Statistics l Write manuscript of results l Publish or perish

Hypothesis vs. Theory vs. Law? l A fact leads to a law, eventually. l What is a law? l Phenomenon that is invariable – is always true l Based entirely on observations, no need for testing l Example of a law?

ice floats gravity

l What happens if all of our experiments fail to negate our hypothesis? l What if workers in other parts of the community, county, state, country, or world also fail to negate your hypothesis?

Theory l A well-tested explanation of the observations (never been proven false.) l We arrive at theories by scientific method

To Prove or Not to Prove l Experimentation can either support or reject a hypothesis. l Experimentation can never prove a hypothesis 100% correct. – why? l 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– 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 l Support, transport l Some photosynthesis l Two types of shoots 1.Vegetative – leaves only 2.Reproductive – produces flowers l 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): l Stolons – above-ground runners l Rhizomes – below-ground runners l Bulbs – swollen underground shoots l Tubers – swollen rhizomes Asexual, vegetative propagation Stores food for later growth

3. Leaves – main photosynthesis organs Petiole Blade

Modified leaves l Compound, doubly compound – why??

Modified leaves Tendrils Spines Succulents

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.