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Theories explain observations ("facts"). Scientists "normally" make observations and use their background of knowledge (existing theories) to explain those observations. Such science is technically defined as "normal science". I will challenge you to perform such tasks from time to time this semester. Note here that I will not accept descriptions of what happened as an answer for such exercises. You must apply explanations from this course. You will know such exercises when they come along, as I will identify them as such. Their purpose is to provide a simple mechanism for understanding scientific thinking, which has great value in almost any area of human endeavor.
I will present complete explanations in this course at the level of the textbook, which is designed to be used as a textbook for non-biology majors. The explanations I will present are scientific explanations. They build on basic information. While I will not expect the high degree of detail expected of a biology major seeking a career in biological or biomedical sciences, I will not sell non-majors short, as people in many different fields, from art to business have profited greatly form a good working knowledge of biology, and I hope to provide all students with the opportunity to develop an understanding of basic biology.
Plants have many basic uses in human society, and we will look at most of them during this course. The focus of this course will be, however, the use of plants as food. While we use plants as a source of building materials, clothing and medicines, our survival is completely dependent upon the ability of plants to synthesize high energy molecules that we use as food. Our economic prosperity is completely dependent upon our ability to provide food at very low cost. Since food is absolutely essential, the greater the expense of time and money food, the lesser the time and money available for all other things, particularly luxuries like a college education.
Traditionally, plants have been considered to be a pure food (we will see more evidence of this in The Harvest of Fear). Ancient references, such as The Bible indicate the traditional consideration of plants as the more wholesome, pure food for humans. In the paradise of Eden, Adam and Eve were sustained by food from plants. Humans are permitted to eat only plants early in Genesis, with the eating of meat permitted by God following the flood.
The first plants cultivated (about 10,000 years ago) were GRAINS, like rice and wheat, as well as LEGUMES such as beans. Other plants, such as those producing fruits and vegetables were cultivated later. Obviously fruits and vegetables were collected from the wild prior to cultivation. Grains in particular have been subjected to selective breeding from times of earliest cultivation. We will look at the origins of wheat in particular later in the course. Even today, grains form staples in our diet, while fruits and vegetables are usually served as side dishes. HERBS and SPICES have come to be used as flavoring for foods. Two common definitions of herbs and spices can be found. One has herb as common plants and spices as tropical plants. The other, which we will use, defines herbs as leaves and stems and spices and roots, seeds and nuts.
Two other basic botanical terms are FRUIT and VEGETABLE. In reality, a fruit is a flowering plant reproductive structure. The defining part of a flowering plant is, of course, the flower:
The structure called the CARPEL is where the seeds develop. Fruits are structures that develop from a carpel, and range from coconuts to tomatoes to apples to walnuts. We will discuss the flower in more detail later in this course. A vegetable is any plant or any plant part. Technically all fruits are vegetables but not all vegetables are fruits. Plant life in general is called VEGETATION. As foods, we have historically referred to sweet tasting plant parts as fruits and unsweet tasting plant parts as vegetables. In this sense, grains are not considered fruits, although technically they are fruits!
The cultivation of plants is the most important activity in civilized cultures. Large scale cultivation of plants for foods by a small number of people in society allows all others to engage in other pursuits. If we each had to grow and/or find our own food, we could not maintain the diverse society we all enjoy. All of the civilized cultures in the world developed around areas that allowed for large scale cultivation of plants. The regions where large scale cultivation of plants has proven most reliable have developed into the most powerful civilizations. Our western European culture developed in the middle east, where wheat has been the basis of agriculture. In the far east, rice has been the basis of agriculture. Central and south American are regions where cultures have developed based on the cultivation of plants like potatoes and corn. As each culture developed, a greater number of plants came under cultivation, like vegetables and spices. The "discovery" of the "new world" by Columbus was driven by a desire to gain easier access to spice producing regions in the far east.
In addition to wheat, the staple, we find most of the fruits, vegetables, herbs and spices that we use today used by ancient Greeks and Romans. Plants such as figs, dates, mustard, basil, marjoram, cumin, lettuce, cherries, cucumbers and many more were commonly used in the ancient Mediterranean cultures. By the middle ages, there were records of the use of plants such as spinach, celery, and broccoli. The first plants imported into the European diet from the far east were plants such as apricots, peaches, cinnamon and ginger. Later plants like orange, eggplant, clove and tarragon were "discovered" and imported in the western European diet. Upon the "discovery" of the "new world", plants like potatoes, sweet potatoes, pineapples, vanilla, and kidney beans were added to the western European diet, resulting in the sort of cuisine that we enjoy in the United States today. Improved techniques of cultivation, shipping, and storage make an array of plants products available to us as food that is unmatched at any time in history, or anywhere else in the world even in the present. One of the most amazing things about our culture is the selection of food products available in supermarkets, as well as the affordability of those products. We all take this for granted, which is one of the riskiest features of our civilization. If there were no food in the supermarket, or if we were limited in both selection and price to what most others live with, what happens to our culture?
We will study the major food plants of the world, their places of origin, the places they are now grown and how they are grown. We must start with the basics, however, which is always the most difficult part of biology to teach. All matter consists of the same basic components, and we must first review those basic components of matter (next lecture!).
What are plants made of? How do plants work? These two basic questions are the focus of the next few lectures of this course. To understand what plants are made of, we need to understand a little of scientific theories about CELLS, which is what we will study in our next lecture.