Notes: Set No. 1
INTERNET LINKS TO USEFUL INFORMATION
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Biology of Plants and the Study of Botany
The following web page
represents a copy of my notes that formed the basis of lectures given during
the first portion of the Biology of Plants (BOT 1103) lecture course.
Please refer to your own notes, handouts, and to the textbook (Stern,
K., R., J. E. Bidlack, and S. H. Jansky. 2008. Introductory Plant Biology,
McGraw-Hill. 616 pp. - reading
assignments are in the syllabus) for additional information.
This web page does not include information found in various handouts and
related materials (e.g., films, charts, overhead projections, etc.) that
you will receive during the course of the semester. You will be evaluated
over this information as well. If you note any errors in the following
document, I'd appreciate it if you would bring this to my attention.
Email address: firstname.lastname@example.org.
Introduction to Course
- Day 1
Instructor of Record: Dr. Martin
Handed out syllabus/course policy to
Reviewed course policy, emphasis on
grade evaluation, examination format, testing dates, make-up policy, etc.
Reviewed general information found in
syllabus (e.g., reading assignments, office phone number, office hours,
to be successful in this botany course!
Read book (reading assignments listed
in the syllabus), exams will cover both lecture and reading assignments.
Beginning of chapters have an outline
and a chapter overview: review these!
Bold-faced headings and terms - know
these terms or concepts.
Read chapter summaries.
Review Questions - some test and quiz
questions will be based on review questions at the end of the chapter.
Look at diagrams and figures given in
each chapter that is covered.
Re-write your lecture notes the same
day these are given.
Cross-reference your notes with the
ones posted on the internet.
The Department of Biological Sciences also offers free tutoring for students
who are enrolled in this and other 1000 to 2000 level undergraduate biology
courses. Contact LSE 202 for more information.
and Topic Outline
Plants - common
examples (e.g., duckweed, redwood tree, etc.) and biodiversity.
Role of plants
in the biosphere.
Effects of Plants
Botany or Plant Biology and the Nature of Science.
associated with plant life and life in general.
Plants - Common examples and biodiversity
Name a plant! (Duckweed,
geranium, apple tree, oak tree, dandelion, algae, redwood
tree, carrot, etc.). Lots
of biodiversity! Plants come in different shapes, sizes. Some
are short-lived, others live for hundreds
of years. Plants have adapted to a wide variety of habitats, and
methods of reproducing and dispersing
According to E. O. Wilson in his
book, "The Diversity of Life" there are about 248,400 species of higher
plants (i.e., ferns, gymnosperms, bryophytes, flowering plants).
There are about 26,900 species of algae.
TAKE HOME MESSAGE - Many species;
biodiversity is high!
Characteristics of Plants
Autotrophs - obtain energy/building
materials by process known as photosynthesis.
Sedentary (Plants don't move about).
Modular construction - repeating units
due to localized areas of growth (meristems); plants grow at their tips
and outward in girth.
Different modules perform specific functions
Roots - anchorage and absorption of
water and dissolved nutrients.
Leaves - absorption of light energy
and atmospheric gases (carbon dioxide).
Reproductive structures; male, female,
or both sexes (e.g., flowers, cones).
Structures that hold spores or seeds
as they mature (e.g., sporangia, cones, fruits).
Stem - support leaves and reproductive
structures, and the link between these modules and the root system.
Upper/lower surfaces of plants are highly
branched. Maximize surface area for absorption of gas, light, nutrients
Cellular level (i.e., eukaryotes/multicellular,
chloroplasts, cell walls, and large vacuoles).
Role of plants in the biosphere
Energy flow from sun to producers; yellow
arrow = sunlight. Energy and material flow from producers
to other organisms; green arrows; material
flow from environment = gray arrow
(e.g., carbon dioxide, water, and nutrients); material flow from consumers
and decomposers back to producers = red arrow
(e.g., carbon dioxide, water, and nutrients). Of the three (producers,
decomposers, and consumers), which two are essential to life on earth?
(Answer: producers and decomposers). Least significant are
the consumers, although these can be important ecologically for specific
plants (e.g., pollination and seed dispersal).
Beneficial Effects of Plants
2. Resupply oxygen to
atmosphere (11 year supply on earth).
3. Maintain the climate
(deforestation is of concern).
CONSIDER DOING THIS:
Make a list of plants and plant products that you have come in contact
over the course of a single day. List the plant and how it was used
by yourself. List a particular usage only once. For example,
don't list tomato if you eat the fruit in a salad or on a hamburger twice.
But if you eat ketchup then list it again. How does this list relate
to the quality of your everyday life?
What kinds of plants/plant products
have you come in contact with today? Examples:
Food, medicine, spices, fibers, paper, clothing, lumber, oxygen,
fuel (coal and wood), toothpicks, toilet paper, paper money, soft
drinks, drugs, and so on.
HOME MESSAGE - Plants are necessary for our continued existence and quality
Brief history of botany.
Early human cultures were hunter/gatherers.
One of the first professions was botany
(plant taxonomy), because it was
important knowledge to be able and distinguish poisonous from
About 8,000 -12,000 years ago something
happened that changed the heart of human
society. What was it?
Agriculture - fossilized plant remains
(e.g., seeds, charred plant remains, pollen) in
archaeological digs of human encampments
place the discovery of agriculture about 8,000 to
12,000 years ago.
Most ancient civilizations (e.g.,
Chinese, Egyptians, Assyrian, Inca, Mayan, etc.) practiced agriculture
regardless of their geographical location in the world. Indigenous
plants (and animals) were domesticated by each respective society.
Two hypotheses about origin of
1. Independent discovery in
different parts of world.
2. Diffusionist hypothesis
- discovery originated in one part of the world and spread from
Plants for food/medicine:
In preliterate societies, knowledge
of what was good or bad was passed on in oral traditions, usually through religious leaders
- the 'medicine man' or shaman among certain North American Indians and their counterparts in
other societies (e.g. priests, rabbis, teachers).
In literate societies, this information was transmitted by means of the written word. Early
Shen Nung, born 2737 B. C., founder of Chinese agriculture, wrote books on drugs and medicines from plants.
|About 300 B. C., the Greek Theophrastus collected information about plants into books including the "History of Plants" and "Causes of Plants". Carolus Linnaeus in the 18th century A. D. referred to Theophrastus as the "Father of Botany".
Dioscorides wrote the "Materia Medica" in the 2nd century A.D., which contained illustrations of plants, just as many modern field guides of wild plants (and other organisms) do today.
|Botany or biology did not progress much during the "dark ages" until the 16th and 17th century. Anton van Leeuwenhoek (1632-1723) was the first to adapt
lenses to the study of living organisms. He discovered microorganisms.
In 1665, Robert
Hooke discovered that plant tissues were composed of cells (in fact he
coined the word "cell").
|The study of plants intensified, with plants being organized into groups and named by taxonomists,
especially by people like Carolus Linnaeus. |
||From the 17th century on to the present day, many different disciplines have developed in the field of botany. Some examples include:
plant taxonomy and biogeography
- plant physiology
- plant ecology
- plant morphology, anatomy, and developmental
- plant cytology (cell structure and function)
- plant genetics
- ethnobotany and economic botany
- genetic engineering - for crop improvement,
insect repulsion, soil reclamation, longer shelf-life of fruits, disease
plant taxonomy and biogeography
plant morphology, anatomy, and developmental
plant cytology (cell structure and function)
ethnobotany and economic botany
genetic engineering - for crop improvement,
insect repulsion, soil reclamation, longer shelf-life of fruits, disease
The field of botany is a culmination of many historical events and consists
of many different scientific disciplines.
Botany or Plant Biology and the Nature of
WHAT IS SCIENCE?
Science is an
organized system of knowledgea obtained by a special methodb,
the "scientific method", of research and aimed at explaining the causes and
behavior of the natural universec.
aThere are different kinds of
knowledgea: e.g., knowledge of a language, literature, automotive
mechanics, cooking, law, philosophy, the meaning of words.
Science is not about proof or absolute
truth. Science is more about reducing uncertainty then stating things as hard
1. Problem or question based on
2. Hypothesis - "education guess" to answer
or explain the question.
3. Experimentation (to determine if the
hypothesis is valid or not).
B. The test
cNatural universe - Science can
say how a guitar string creates sound when plucked, but it can say little about
the aesthetic value of music. Science can say nothing outside it's realm of
expertise, in regard to ethics, morality, and the supernatural.
scientists engage in scientific research, most of them don't sit down and think,
"Gee, I think I'll make an observation. What kinds of questions come to mind?
Perhaps I should write down some potential hypotheses. 1,2,3, 4 etc. Ah, now
let's see, I will do an experiment to test one of my hypotheses. I will engage
in inductive and deductive reasoning". Scientists don't act like the
stereotypic characters on television shows (e.g., Mr. Spock from Star Trek or
the Professor from Gilligan's Island). Creativity, personal biases, hard work,
hit and miss speculation, experimentation, availability of funds and resources,
existence of appropriate technology, and dumb luck all come into play. The
reason for outlining the "scientific method" is to try to dissect the essential
elements of the process. Also scientists aren't like Bill Nye - the science
guy, Mr. Wizard, or Beakman from Beakman's World. These are science educators,
but when they do experiments they already know what the outcome of the
experiment will be. Not so with scientists.
FACT: a confirmed or, at least, agreed-upon
empirical observation (or conclusion if referring to an "inferred" fact). For
example, a fossil is generally accepted by most biologists as evidence for life
in the distant past, even if the apparent life form no longer exist in today's
world (e.g., dinosaurs, ammonites - an extinct mollusk, etc.). That fossils are
the remnants or the products of something once alive is an inferred fact, even
though the living organism is no longer present.
HYPOTHESIS: a proposed explanation of certain "facts" that must be
empirically testable in some conceivable fashion.
THEORY: an integrated, comprehensive explanation of many "facts" and
an explanation capable of generation additional hypotheses and testable
predictions about the way the natural world looks and works. A generally
accepted scientific theory is a well-tested hypothesis supported by a great deal
of evidence. The scientific definition of theory is different then what is used
by the lay person - like a guess. "Oh well, it's only a theory". In fact a
theory is well tested, and if consistent with the data, possesses a high degree
of certainty (although not equivalent to proof).
Something Fun to Think About: Chaos, Fractals in Nature
(including Plants), and the Nature of the Universe at
Activities associated with plant life (and life in general).
In your mind consider the question
of which of the following objects you would consider to be alive and not
alive. At beginning of this section, ask the class which of the following
objects is alive. A frog, a stone, a virus, a seed, and a tree.
What did you base your answer on?
Most people have an intuitive feel or sense for determining
what is alive or not alive.
But coming up with a precise definition is difficult. In 1994, a
conference of scientists argued
whether or not viruses, which appear to have properties of both
being living and nonliving were
alive or not. One scientist, by the name of Stephen Hawking
has publicly argued that not only
are biological viruses alive, but that computer viruses constitute an artificial
Living organisms share certain characteristics
or activities that separate them from non-living
matter. What are some of these?
Structure/organization, which arise
from the basic properties of matter and energy.
Metabolism - "energy transfers".
Homeostasis - Maintain a livable internal
Response to stimuli (e.g., temperature,
injury, light, gravity, etc.).
Mutations or changes in form are possible.
Adaptation to the environment.
Interdependence among organisms (no
tree is an island unto itself!).
Blueprint of life is coded by DNA.
and Topic Outline
plant cells and the microscope.
of the plant cell.
Discovery of plant cells, the microscope and cell theory.
In 1665, Robert Hooke using
a crude light microscope saw and described cells in a piece of cork. This is a
of how certain discoveries are dependent on the development of appropriate technology. The
discovery of cells was dependent on the development of the light microscope. Can you think
of any other examples where this is true? [Laboratory
equipment and procedures
(e.g., refrigeration, electrophoresis, ultracentrifugation, etc.) required
for many types of scientific study would not be possible without a grasp
of basic technology, such as, the production and use of electricity, which
has only been around for about one century; Detailed discoveries
about our solar system were dependent on development of rocket propulsion
systems, computers, educated and technologically sophisticated support
to make visual observations:
Which is more important? Resolution,
it is useless if you magnify something a thousand times if
it appears fuzzy. Resolving
power of a light microscope is about 0.2 micrometer or microns or 200 nanometers
(nm). If distance between two objects is less than 0.2 micron,
we see them as a single object. Resolving power of
electron microscope is about 10 nm or about 20 times greater resolution
than is possible with the best light microscope.
Components of the plant cell.
Parts of the plant cell
Cell wall - cellulose forms micro- and
macrofibrils which are held together by pectin and related substances.
primary cell wall - cellulose,
secondary cell wall - inside primary
cell wall, cellulose, hemicellulose, and lignin (complex alcohol
plasmodesma (singular), plasmodesmata
(plural) - holes in the wall that act as channels for protoplasm movement
between cells middle lamella - pectin.
Plant cell shape - keep in mind that
not all plant cells are box-shaped - for example, the epidermal cells of
geranium leaf are shaped and arranged like pieces of a jig-saw puzzle.
Plasma membrane is semi-permeable (channel
and carrier proteins are responsible for active and passive transport.
Phospholipid bilayer membrane - follows 'fluid mosaic model of cell membrane
Cytoplasm or protoplasm - fluid matrix
that organelles are embedded in, largely made of water and dissolved substances
(proteins, sugars, salts, etc...). Also contains the cytoskeleton (network
of protein fibers) that help to anchor organelles and help give the cell
Nucleus - chromatin or chromosomes (DNA
and protein) + nucleolus (nucleolus organizer region - NOR on some chromosomes)
which produces rRNA which is found complexed with protein in the ribosomes
(protein synthesis). Bound by membrane - nuclear envelope which contains
Endoplasmic reticulum - rough (with
ribosomes) and smooth (without ribosomes) - channels of membranes involved
as site of protein and lipid synthesis and movement of protein products.
Golgi apparatus or body = Dictyosomes
- storage of proteins, lipids, and carbohydrates.
Flagella and Cilia are made up of microtubules
in a 9 + 2 arrangement - movement.
Lysosomes and peroxiosome - membranebound
vesicles which contain enzymes for the breakdown of organic compounds (the
latter uses oxygen and produces hydrogen peroxide).
Mitochondrion - power house of the cell
- aerobic respiration.
(e.g., chloroplasts - associated with photosynthesis, leucoplasts - starch
amyloplasts) or oil storage (elaioplasts), chromoplasts - carotenoid-containing).
- bounded by a membrane, the tonoplast,
and often containing crystals and soluble pigments, such as anthocyanin,
in the cell sap.
Plant cells lack centrioles, which occur
in pairs, composed of microtubules.
Cell Division: Mitosis and cytokinesis
Cytokinesis - cytoplasmic division|
Mitosis - nuclear division|
Both processes occur in specific parts
of plant called meristems.|
primary growth - usually found at the
tips of stems and roots
secondary growth - vascular cambium,
cork cambium = phellogen (found in some herbaceous and woody plants but
lies between vascular cambium and bark).
is composed of G1, S, and the G2 phase. The cell cycle follows:
G1 (gap 1 - interval before DNA replication and protein synthesis) ===>
S (synthesis - replication of DNA and protein synthesis) ===> G2 (gap 2
- interval before onset of mitosis) ===> MITOSIS
CYTOKINESIS===> G1 ......
Prior to and after mitosis (i.e., during
interphase), the material in the nucleus (chromatin) is uncondensed.
Chromatin is made of about 60 % protein
and 40 nucleic acid.
Chromatin = uncondensed chromosomes.
Chromosome size, morphology, and number
various from one species to the next:
- Broad bean - Vicia faba (haploid,
n=6; diploid, 2n=12)
- Corn - Zea mays (haploid, n=10;
- Cotton - Gossypium hirsutum (haploid,
n=26; diploid, 2n=52)
- Evening primrose - Oenothera biennis
(haploid, n=7; diploid, 2n=14)
- Garden onion - Allium cepa
(haploid, n=8; diploid, 2n=16)
- Garden pea - Pisum sativum (haploid,
n=7; diploid, 2n=14)
- Green alga - Chlamydomonas reinhardi
(haploid, n=16; diploid, 2n=32)
- Jimson weed - Datura stramonium
(haploid, n=12; diploid, 2n=24)
- Snapdragon - Antirrhinum majus
(haploid, n=8; diploid, 2n=16)
- Tobacco - Nicotiana tabacum (haploid,
n=24; diploid, 2n=48)
- Tomato - Lycopersicon esculentum
(haploid, n=12; diploid, 2n=24)
- Water lily - Nymphaea alba (haploid,
n=80; diploid, 2n=160)
- Wheat - Triticum aestivum (haploid,
n=21; diploid, 2n=42)
chromosomes vs. duplicated chromosomes.
- nuclear division
- cytoplasmic division and cell plate formation. Both mitosis and
cytokinesis need to take place for cell division to occur.
Prophase - chromosomes begin to condense/nuclear
membrane breaks down, nucleolus disappears.
Movement is coordinated by organized
arrays of microtubules called the spindle apparatus.
In animals and fungi these fibers radiate
from centrioles - plant cells do not produce centrioles, although the spindle
apparatus still forms.
Metaphase - chromosomes move to the
center or equator of the cell.
Anaphase - sister chromatids are pulled
apart toward the poles.
Telophase - chromosomes decondense,
nucleoli reform, nuclear membrane reforms, spindle fibers disappears, cell
some very helpful information visit the following Web Site:
Biology I Animations,
Movies & Interactive Tutorial Links. Visit the categories: Cell Structure
& Function, Cell Transport, and Mitosis/Meiosis. You may find it quite
informative, though some links are better than others.
and Topic Outline
Types of tissues.
TYPES OF TISSUES
Plant cells form the basis for plant
tissues (i.e., meristematic, simple, or complex), which in
turn form the basis for various
organs (e.g., leaves, roots, reproductive organs, etc.). Tissue patterns in roots and stems vary
among woody dicots, herbaceous dicots, and monocots.
Apical meristems are responsible
for primary growth. Vascular and cork cambium is
responsible for secondary growth.
Secondary growth is not common to all plants, predominates in woody species.
gives rise to 3 types of primary or transitional meristems ==> protoderm
ground meristem (becomes cortex and pith, or ground
tissue), and procambium (becomes vascular tissue). Primary
growth occur at the tips of shoots and roots.
==> secondary growth
vascular cambium, increases girth of
stem, replaces dead phloem and xylem.
cork cambium = phellogen ==> cork and
parenchyma cells to replace the damaged epidermis ==> periderm.
nodes (grasses - growth at the base of nodes, responsible for
stem elongation; allows grass to replace its growth after
fires, herbivory, and mowing.
IV. COMPLEX TISSUE
- found in roots, stems and leaves, undifferentiated thin-walled, large
vacuoles, often contain secreted material (starch, oils, tannins, crystals).
- parenchyma tissue with extensive intercellular air spaces (e.g., water
lilies and spongy mesophyll of leaves).
- parenchyma with numerous chloroplasts (common in leaves).
- thick-walled but flexible and strong, usually right below the epidermis
of a leaf or stem, used for support in stems and leaves of non-woody or
- thick walls impregnated with lignin, usually dead at maturity, function
- stone cells in pear, hard part of seeds and nutshells (cells are long
as they are wide).
- much longer in length than they are wide, fibers are used in rope, textiles,
canvas, paper money (common sources are hemp, cotton, and flax).
- outermost layer of cells covering a plant. Functions for purposes
of absorption (carbon dioxide and water) and protection (from water loss
and pests). Usually one-celled thick, although some plants have a
multicellular epidermis (orchids have velamen roots to prevent water loss).
The epidermis is covered by a fatty substance called cutin (the cuticle)
to prevent dehydration and enhance pest resistance. Openings in surface
of epidermis are called stomata (pl.) or stoma (sing.). Opening created
by two guard cells which are sausage (dicots) or bone shaped (monocots).
Only the guard cells in the epidermis possess chloroplasts.
epidermal outgrowths. Examples include, glands on leaves (mint, geranium,
marijuana (tetrahydrocannabinols - THC), protective hairs of stinging nettle,
trichome fibers on seeds of cotton (95 % cellulose).
In roots, tubular extensions arise from
epidermis (root hairs). Greatly
increases the surface area for absorption of water by several thousand
tissue - made of more than type of cell. Three types include
the xylem (vascular
tissue), phloem (vascular tissue),
the periderm (part of the bark of woody plants - cork and
parenchyma cells) and secretory
transports water and dissolved substances
This tissue is composed of parenchyma,
fibers, vessels and/or tracheids, and ray cells.
Vertical movement of water and dissolved
vessels - are made up of vessel elements
joined end to end like a series of drinking straws. Dead at maturity.
tracheids - possess tapered unopened
ends. Dead at maturity.
Horizontal movement of water and dissolved
mineral nutrients through ray cells - horizontal rows of long-lived
parenchyma cells produced by ray initials in the vascular
Secondary xylem is produced by the vascular
Cone-bearing trees contain mostly tracheids,
while flowering trees contain vessels/tracheids.
Phloem is involved in the conduction
of dissolved food, sieve-tube members (no nucleus at maturity, cytoplasm
present), companion cells, fibers, parenchyma, and ray cells. Sieve-tube
members and companion cells arise from the same cell. Found in flowering
Sieve cells occur in non-flowering plants
associated with albuminous cells (parenchyma cell) which are not derived
from the same cell. Albuminous cells regulate activities of sieve
In woody plants the epidermis is sloughed
off by periderm from the cork cambium.
Cork cells are dead at maturity, cell
walls contain a fatty substance called suberin.
Lenticels - open surfaces in bark that
arise from periderm, loosely packed parenchyma cells. Lenticels are
involved in gas exchange.
nectar (flowers) from nectaries
oils (peanuts, oranges, citrus) from
accumulation of glands and elaioplasts.
resins (conifers) from resin canals
lacticifers (e.g., latex - milkweed,
rubber plants, opium poppy)
hydathodes (openings for secretion of
digestive glands of carnivorous plants
salt glands that shed salt (especial
in plants adapted to environments laden with salt).
FOR IMAGES OF PLANT CELLS AND TISSUES: CLICK ONTO LINKS LISTED AS CELLS
This page is maintained by Dr. Martin Huss. Last modified September 6,