Textbook Notes: Biol 120 – Plant Biology
“Introduction to Botany” by M. W. Nabors
Chapter 1: The World of Plants
• Many plant bi-products (alkaloids), are used commercially,
as well as narcotics.
o caffeine, ephedrine, morphine, nicotine, cocaine, etc.
• word botany, derived from Greek word meaning “plant”.
• photosynthesis: the process by which plants and certain other
organisms use solar energy to usable energy by converting
CO2 and H2O into chemical energy.
o ~ ¼ of the 1.5m known species of living organisms are
o plants, bacteria, and algae carry out most of the
photosynthesis – but mostly plants.
• biosphere: the thin layer of air, land, and water occupied by
• Photosynthesis supports life in 3 ways:
1. it produces almost all of the world’s oxygen.
2. almost all organisms attain their energy directly or
indirectly from photosynthesis: herbivores consume
plants, carnivores consume herbivores, etc.
3. The sugars produced via photosynthesis are the building
blocks of life. They are combined with minerals from the
soil to make a large variety of structural compounds.
• Humans began to cultivate crops ~12-14kybp.
o agriculture became the foundation for human
o began to select crops with specific features/benefits,
and increase yield.
o most human food focuses on corn, wheat, and rice.
o 80% of human caloric intake is provided by 6 crops:
wheat, rice, corn, potatoes, manioc/cassava, and sweet
o alcoholic drinks are also derived from fermented plant
o dried herbs and spices used for flavoring. • Plants are used for medicinal purposes.
o aspirin – similar to salicylic acid, found in tree bark.
o 1500’s - books documented practical uses for plants
and plant products.
o 1600’s – quinine powder from the bark of cinchona tree,
began to be used for malaria treatment.
o ephedrine – antihistamine produced by plant genus
o ~25% of prescribed drugs contain at least one product
derived from plants.
• Wood is used extensively in both developing and industrial
o most important use of fuel for cooking and eating, as
much of the world still does not have access to
o fossil fuels are fossilized remains of plants.
o Wood is main use for construction material.
o paper is made from mostly the pulp of woody plants.
• Conservation Biology: is the multidisciplinary field of
science that studies ways to counter the widespread
extinction of species and loss of habitats. It studies the
impact of human activity on all facets of the environment.
o ~ ½ of the world’s forests are gone.
o rainforests are cleared through “slash-and burn”
o clearings are used for agriculture until the soil is
depleted of nutrients, and then it is abandoned.
o estimates say that ~ 2700 species of organisms go
extinct each year.
o 20% of all tropical species became extinct between
Plant biotechnology: focuses on efforts to obtain improved plants
and plant products using scientific techniques.
DNA (deoxyribonucleic acid): a self-replicating material present in
nearly all living organisms as the main constituent of chromosomes. It
is the carrier of genetic information.
genes: a unit of heredity that is transferred from a parent to offspring
and is held to determine some characteristic of the offspring. genetic engineering: a new method of biotechnology; the deliberate
modification of the characteristics of an organism by manipulating its
• “Golden Rice” – engineered rice, in which the addition of two
daffodil genes and one bacterial gene enabled the rice plant
to produce carotene, a source of vitamin A.
• Pest resistant plants – the addition of Bt gene makes crops
resistant to particular insects, therefore allowing farmers to
avoid the use of excessive pesticides.
• Edible Vaccines – genes of certain bacterial diseases can be
inserted into plants that people eat; ie, E.Coli gene entered
into potatoes triggered an immune response in those that
consumed them, and produced antibodies that made them
resistant to the disease.
• Herbicide resistant plants – crops are made resistant to
herbicides that are used to kill weeds.
Questions are on pg. 11
Evolution - the process by which different kinds of living organisms
are thought to have developed and diversified from earlier forms
during the history of the earth.
Characteristics of Plants:
• Plants are multicellular eukaryotes.
o eukaryotes: organisms that have a nucleus, and
membrane bound organelles.
o prokaryotes: do not have a nucleus that encases their
DNA, or membrane bound organelles.
• Plants are photosynthetic.
o autotrophs: an organism that is able to form
nutritional organic substances from simple inorganic
substances such as carbon dioxide. – plants are
o heterotrophs: an organism deriving its nutritional
requirements from complex organic substances.
• Plants have walls composed of cellulose.
o cellulose: consists of a chain of glucose molecules.
o cellulose is distinctive of plants among the eukaryotes,
because algae and fungi normally have cell walls
composed of other materials.
• Plants have two adult forms that alternate in producing
o Gametophyte and Sporo