An Introduction to Plants and Their Study

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Chapter 1

• An Introduction to Plants and Their Study

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Importance of Plants

• Producers of food and O2 for other organisms
• Also produce medicines used in the treatment of
  various diseases, especially cancer treatments
• Produce things from limber to rope to oil to
  spices to coffee to tea and beer
• All are influenced directly or indirectly by
  plants
• beneficial
• detrimental poison ivy, allergies, illegal drugs

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Balanced Nutrients

• Cereals provide most of the calories in the form
  of carbohydrates
• basis for civilization grains allowed people to
  stop moving, rather grow crops
• Legumes (seeds) provide protein
• Different types of building blocks in these
  molecules

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Agriculture

• 13,000 years ago we were hunter-gatherers
• move or starve
• 12,000 years ago begin to grow cereal crops
• 10,000 years ago become herders of animals and
  improved farmers

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Development of Ecology

• Birth of agriculture lead to ecology
• Ecology is effects of environment on plants and
  start to see artificial selection
• farmers started to choose seeds from useful
  plants for next years crops
• eventually found ways to preserve food

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Agriculture

• Started in the Fertile Crescent then to Europe
  and the America
• Many plants were domesticated by Native Americans
  
• Incan Indians of Peru used techniques for soil
  erosion prevention

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Plantae Kingdom

• Drugs can be made from plants that are useful to
  humans and can protect the plant from predators
• birth control from yams
• cocaine from poppy stimulant and hunger
  depressant
• resperine from evergreen sedative and blood
  pressure, schizophrenia treatment
• digitoxin from foxglove heart medication
• hemp marjuiana relieves side effects of chemo
• pyrethrum from chrysanthemum treat head and
  body lice, pesticide
• Table 1.1

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Study of Plants

• Ethnobotany study of the use of plants by
  ethnic populations
• Understanding of economically important plants
  will help us improve them and protect them

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What is a plant?

• Share things in common with other organisms
• take in and use energy
• single to multi-cellular
• reproduce
• respond to environment
• share common ancestry and co-evolve with others

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What is a plant? continued

• Unique characteristics
• autotrophic make their own food sugar,
  protein, vitamins and amino acids humans are
  heterotrophic which means they get food from
  other organisms
• have special pigments called chlorophyll to make
  sugars and cellulose as structural carbohydrate
• non-motile cant move but some plants have
  adaptations that allow them to rotate to get the
  most advantage of the suns energy
• open or indeterminate growth no restriction on
  size
• reproduce asexually (no egg and sperm fusion,
  vegetative) or sexually

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Typical Plant

• Leaves, stem and roots
• 2 types of plants that produce seeds to make new
  plants
• Angiosperm flowering plants
• Gymnosperm - evergreens

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Seeds

• Contains the embryo young plant
• Seed provides protection and nourishment until
  can do on own
• Seed coat outer protective layer thin and
  papery like a peanut the shell of the peanut is
  the fruit wall
• Flowering plant seeds have fruit coverings, even
  pine trees cover seeds in the cone

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2 Types of Seeds

• Monocots - monocotyledons
• Produce seeds with 1 cotyledons seed leaf
  modified leaf for food/energy storage
• Grains wheat, oats and grasses

• Dicots dicotyledons
• Produce seeds with 2 cotyledons
• 2 cots with the embryo in between
• Oaks, roses, beans

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Seed Structure

• Epicotyl above the cotyledon attachment and
  gives rise to the shoot
• Hypocotyl is below the attachment
• Radicle is the embryonic root and is usually at
  the tip
• Some seeds such as corn and grass have a partial
  protective sheath

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Growth of a Plant

• First root provides H2O and nourishment
• Shoot pushes up thru dirt
• hypocotyl elongates (fastest growing part) and
  forces the apical meristem above the surface
• Cotyledon supplies energy from the endosperm
  found in the seed
• Depending on seed, cotyledon may come above the
  soil or stay below

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Grasses

• More complex
• Seed stays in the ovary wall, germinates when
  coleoptile sheathes the shoot and coleorhiza
  sheathes the radicle then we see growth
• Radicle breaks thru coleorhiza and becomes 1st or
  primary root which stops growing
• Leaf pushes out and becomes photosynthetic
• Cotyledon provides sugars from endosperm until it
  makes enough of its own

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Roots

• Used to collect H2O and minerals for the plant
• Few to many per plant
• 1 or several primary roots and the rest are
  secondary
• Tip is covered by root cap that produces mucilage
  helps root move thru soil
• Root hairs increase the surface area of the root
  and therefore can gather more H2O and nutrients

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Functions of Roots

• Anchorage holds plant in place
• Storage holds energy reserves concentrated in
  the roots of a biennial (2 year life cycle)
  sugar beet an carrot, used by humans/animals as
  food source before plant can use for growth and
  reproduction
• Conduction transport of H2O and nutrients, some
  even move CO2
• Absorption picks up H2O and nutrients from soil

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Root Systems

• Can cover many m2 of ground area (2º) and as deep
  as 30 m (1º)
• Grasses have very shallow root systems and that
  is why they are used for soil erosion control

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Shoots

• Stems and leaves
• Node leaves and axillary buds attach to stem
• Axillary bud is above the upper junction between
  leaf and stem and is an immature leaf and stem
• Internode is the area between nodes

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Functions of the Stem

• Support for
• leaves to collect sunshine for photosynthesis,
  herbaceous plants (non-woody) also function in
  photosynthesis
• flowers to get pollinated
• fruits for distribution
• Storage starch and water large amounts
• Conduction transport of H2O and minerals
  between roots and leaves

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Hypothesis Driven Science

• Scientific Method
• Series of steps that start with observations and
  questions that then form a hypothesis which is a
  tentative answer to some question
• Use deductive logic to test the hypothesis
• reasoning moves from general to specific
• Perform experiments to see whether results are as
  predicted and then you generate conclusions
• must be objective when developing conclusions

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Scientific Method
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Biotechnology

• Use organisms to make commercial products
• Manipulate plant and animal genomes
• Use biotechnology to make plants resistant to
  drought, disease and insects
• Bacillus thuringiensis used in cotton to
  protect from boll weevil and corn from the corn
  bore worm