Chapter 1-Plants in Our World Formation of earth-4.5-4.6 billion years ago Evidence of life from organic material-3.8 billion years ago Many cyanobacteria are photosynthetic, but these microscopic organisms have a much simpler structure than plants
Photosynthesis First eukaryotic organisms-1.9-2.1 billion years ago
The eukaryotic nucleus and endomembrane system are thought to have originated by infolding of the cell membrane in an ancestor of modern eukaryotic cells. Modern protist lineages, fungi,animals, and plants inherited mitochondria from early protists.
First photosynthetic eukaryotic organisms-1.5 billion years ago Because all modern eukaryotic organisms known to contain plastids also possess mitochondria, it is thought that algae acquired plastids after mitochondria through endosymbiosis
This eukaryote capable of carrying out photosynthesis via endosymbiosis with its captured partner is considered the first plant from which all plants are subsequently descended. Importance of Photosynthesis
Over millions of years, plants have radiated into several major groups. Devonian Era-evolution of the first seed plants Gymnosperms
Gymnosperms Key innovations in the evolution of land plants were pollen and seeds. Packaging the embryo into a seed enables plants to surround the embryo with nutritive tissue, providing for the early survival of the embryo. Jurassic Period-evolution of flowering plants-200 million years ago
Angiosperms Cretaceous Period-angiosperm radiation The diversification of the angiosperms over 100-200 mya was due to selection imposed by interactions with other plants, fungi bacteria and animals.
There is evidence that the increase in diversity with the origin of seed plants and then evolution of angiosperms followed events of genome duplication. The theory that Neanderthals disappeared due to a focused meat-based diet has been laid to rest by recent research by scientists from the Smithsonian and George Washington University. The evidence they collected shows that Neanderthals ate grains, seeds, and even palm fruits. http://www.mnh.si.edu/highlight/neanderth al_diet/
Different plants were available all over the world, and people developed their own unique uses for plants. Use of flowering plants for food Plants are defined as organisms that: 1)are multicellular 2)have cellulose cell walls 3)have chlorophyll and are photosynthetic (or originated from photosynthetic ancestors). 4) are adapted to in many ways to life on land (or if aquatic, are descended from land-adapted plants). Because flowering plants are the most important in terms of human goods and services, they are the focus of this course. Our definition of a plant becomes more specific to flowering plants:
All plants have growth points for shoot and root tips called apical meristems. Root apical meristems are much simpler, being primarily root tips. Shoot apical meristems occur at the tips of the shoots, buried inside the developing leaves. Plants also provide many secondary compounds: Other plant compounds are important for: Putting Order into Plant Diversity Historically, there have been two independent kinds of nomenclature. 1)Common names 2)Scientific names Through the ages, humans have given organisms common names Scientific names- (Binomial system) Carolus Linnaeus (1707-1779) (originally Carl von Linné) Carl von Linné, Alexander Roslin, 1775. Currently owned by and displayed at the Royal Swedish Academy of Sciences.
Scientific names Two-word name consisting of: 1) Generic name 2) Specific epithet Ex: Zea mays Generic Specific name epithet Generic names - Generic name (genus name) is treated as a Latin noun. - Capitalized - Underlined or written in italics. What is a genus? Genera that originate from a common ancestor and share one or more derived characters are clustered together in a plant family. https://botanistinthekitchen.wordpress.com/
Specific epithet Major plant organs There are two major types of root system: Roots play a variety of roles in plants -roots anchor plants and absorb water and minerals -some roots are useful as human food -roots are important sites of hormone production -the roots of some plants help support stems
Adventitious roots develop from the shoot system. Stems are fundamental plant organs with multiple functions. grow by activity of apical meristems -store food materials and sometimes serve as photosynthetic organs. -conduct sugars produced in leaves -transport water and materials from roots The function of phloem is primarily the movement of sugar from one part of the plant to another. Xylem is involved in the transport of water and (usually) dissolved mineral nutrients.
Modified stems Leaves are complex structures composed of 4 main types of tissues:
Modified leaves Reproductive Structures If a flower has both androecium and gynoecium (male and female) it is called a perfect flower. If only one sex is present, it is an imperfect flower.
Monoecious example Dioecious example http://www.nzdl.org The elaboration of flower shapes, sizes and colors that we see usually reflects the way in which the flowers are pollinated.
Fruits Every sexually reproducing flowering plant bears some type of fruit that serves the purpose of protecting the seeds and dispersing them to areas for germination. Seeds Within fruits, there are usually one or more seeds that contain an embryo, variable amounts of stored food and a protective coat derived from maternal tissues. Within fruits, there are usually one or more seeds that contain an embryo, variable amounts of stored food and a protective coat derived from maternal tissues.
Study outline-chapter 1-Plants in Our World Understand important major geologic events in the history of plants (Table 1.1) -formation of the earth -evidence of life -first photosynthetic prokaryotic organism -definition of photosynthesis (Figure 1.2) -first eukaryotic organism -endosymbiotic theory/eukaryotic evolution/mitochrondial evollution -first photosynthetic eukaryotic organism -plastid evolution -importance of photosynthesis in plant evolution -5 major plant groups that evolved (Figure 1.3) -bryophytes, lycophytes, ferns, gymnosperms and angiosperms -evolution of the first seed plants -gymnosperms cycads, ginkgophytes, conifers and gnetophytes -key innovations in the evolution of land plants (pollen and seeds) -evolution of flowering plants (Figure 1.3) -characteristics of angiosperms -angiosperm radiation -understand important evolutionary changes that was influenced by angiosperm radiation -morphology, secondary compounds that influenced pollinators and predators, and genome duplication -Understand how different plants available around the world influenced diet and culture -Understand general definition of plants from General Botany and the more specific definition to flowering plants in the Plants in Our World course -Understand general structure of apical meristem -shoot apical meristem (SAM) and root apical meristem (RAM) -Understand common names vs. scientific names -Understand the definitions of generic name, specific epithet (Table 1.3), genus and family -Understand characteristics of major plant organs -Roots characteristics of roots; tap vs. fibrous (Figure 1.10); modified root examples -Stems characteristics of stems; vascular bundles (Figure 1.12); monocot vs. eudicot stem; modified stem examples -Leaves characteristics of leaves (Figure 1.14); leaf examples (Figure 1.15) -Understand reproductive structures -flower structure (Figure 1.9); perfect vs. imperfect ; monoecious (Fig. 1.18) vs. dioecious; flower type and pollinator (Fig. 1.20) -general characteristics of fruits (Figures 1.23 and 1.24) -general characteristics of seeds; monocot vs. eudicot seed (Figure 1.10); features of seeds that make them good sources of food