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Lab Practicum ReviewWhat does iodine test for?
What are adventitious roots?
Why does fresh potato cause bubbling when in peroxide?
Can you identify a X.S. of a leaf, stem or root under the
microscope?
What are simple or compound leaves? Can you identify leaves as
such?
What are the types of germination?
Stem structure, both external and internal.
What are the differences between a monocot verses a dicot
leaf?
Leaf anatomy epidermis, mesophyll, stomata, etc.
What cells/tissue in plants make up what is termed wood?
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Photosynthesis ..the equationMetabolism .. the equation
What is a cambium and what does it do in a plant stem?
The plant cell verses animal celldifferences
Plant flowers external features like sepals, petals, pistil and
anthers
Functions of plant ovary or anthers
Anabolic verses catabolic metabolism (photosynthesis verses
respiration)
DNA transcription, translation
Mitosis verses meiosis
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Seed dispersal mechanisms
Dehiscent vs nondehiscent fruit
Genetics/monohybrid and dihybrid crosses ..Mendel
Adaptation to the environment .anatomical changes: sunken
stomates, reduced leaf size, hairs, thickened cuticle and external
morphology such as lost leaves, thickened water storage stems,
etc
Nucleotide bases of DNA and RNA (G,C,T,A and G,C,U,A)
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Modified Stems - Several examples of modified stems are setup
around the lab. Examine each and find the features common to stems
and how they have been modified from normal stems.
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Guard cells of stomates in monocot grasses (upper figure) and
broadleaf dicots (lower figure)
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Leaf Modification - Plants have adapted their leaves to survive
environmental extremes, as protective structures, to aid in support
and even to catch and provide nutrition (insectivorous plants).
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Below is a cross section of an ovary.
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Plants undergo double fertilization
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Insect pollination is responsible for producing 80% of the fruit
and vegetables we consume. Wind, water and animals also help to
transfer pollen.
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Dicot seed on the left; monocot seed on right
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Seed dispersal often requires new ground which can could be as
simple as a field that has been plowed or a newly formed volcanic
islandIn all these scenarios plants will eventually appear and
grow. Seed dispersal is what allows for this to happen and occurs
through a variety of mechanisms that have evolved over thousands of
years.
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Seed dispersal starts first with the fruit and whether it stays
on the mother plant and releases the seed (dehiscent fruit) or
where the seed stay within the fruit (nondehiscent fruit) which
then falls or is released from the plant. Examples of dehiscent
fruit are follicles, pods and capsules.
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Wind Do you remember as a child taking dandelions and blowing
their fuzz around? Of course the fuzz was seed that had feathery
plumes or parachutes. The seed was so light that your breath could
carry them quite some distance across a lawn. Your actions were
mimicking what would happen naturally with a strong wind in the
dispersal of these seed.
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Water Most of the earths surface is covered with water. Water
tends to move either through gravity or wind forces. Consequently,
water provides an excellent method for dispersal for some plants.
Plants such as Mangrove and Coconut have seed with entrapped air
that makes them buoyant. These seed can drift literally thousands
of miles before washing up on a shore where they can take root and
grow.
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Additionally, there is dispersal by animals after they eat the
fruit, seeds that hitchhike by attaching to clothing or fur
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At the heart of this collection system is chlorophyll, a
chemical substance capable of capturing photons of light and
generating a high energy electron that can be used for the
synthesis of food.
Photosynthesis
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3-D Illustrations of the chloroplast
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There are basically two major steps in photosynthesis required
to produce the carbohydrate (sugar). The first requires light
energy (light dependant reaction). This energy is ultimately
captured in the form of high energy compounds that we have already
studied in respiration (ATP, NADH, etc). Note that the light
reaction DOES NOT in itself produce any carbohydrate. The high
energy compounds are shunted to the stroma of the chloroplast where
the second reaction (the light independent or dark reaction) occurs
to produce the carbohydrate. Like the krebs or citric acid cycle of
respiration, the dark reaction is also cyclic and is known as the
Calvin-Benson cycle.
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Glycolysis
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The diagrams below show the chemistry of this conversion. Note
that in alcoholic fermentation CO2 is produced, but not in lactic
acid fermentation.
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Krebs Cycle, TCA Cycle or Citric Acid Cycle
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Terminal Oxidation
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Desert Adaptations - With desert conditions, conservation of
water is extremely important to survival. Rainfall averages less
than 10 inches per year. Consequently, plants have evolved ways to
conserve or store water. Among these adaptations are:
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Water storage tissues in stems or leaves Leaves absent, reduced
in size or short lived only when there is rain Deep root systems to
reach water or very wide root systems that efficiently capture
water after a rainfall Plants may produce a heavy thick cuticle of
wax on leaves and stems to reduce water lossAnatomically those
plants that retain their leaves may show anatomical changes such as
reduced number of stomates, sunken stomates or hairy stomates
(protective trichomes that reduce water evaporation) Leaves may
develop numerous trichomes (hairs) that shade the leaf and reduce
water lossPhotosynthesis desert and arid land plants may use C4
photosynthesis rather than C3 photosynthesis. Consequently C4 plant
will show a different anatomy (Krans anatomy) in the leaves where
the mesophyll is arranged around the bundle sheath cells of the
veins. Additionally, the bundles sheaths will contain chloroplast
in the C4 leaf whereas chloroplast are absent in the C3 leaf.
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Temperate Grasslands Adaptation - Grasslands, also called
prairies, have hot summers and cold winters. Rain is sparse and
droughts common. Average rainfall is 10 - 30 inches a year. The
soil of grasslands is very rich in organic matter from the annual
grasses that die off and enrich the soil. Farming has claimed the
majority of original grasslands. Only small patches or pockets of
original grassland remain. Adaptations include:
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Roots survive fire and resprout
Prairie trees have thick bark for fire protectionRoot systems
are so extensive that grazing animals cannot pull the plants from
the groundShrubs resprout readily after a fire Narrow leaves of
grasses have less water loss compared to broad leaf plantsExtensive
and deep root system to obtain waterFlexible stems that can bend in
the winds typical of prairiesMost grasses use the wind for
pollenationSome grasses also utilize C4 photosynthesis
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Temperate Deciduous Forest Adaptations This climate zone is most
familiar to us here in the Ozarks. We have 4 distinct seasons;
spring, summer, fall and winter. Consequently temperatures vary
from freezing in winter to hot in summer. Rainfall is from 30-50
inches a year. Due to both the abundant rain and seasonal
temperature changes, the temperate deciduous forest plant ecosystem
is layered with plants of different heights. The canopy of the
forest may be over 100 feet tall, followed by an understory of
smaller shade tolerant trees and young trees. Finally beneath the
understory are is a shrub layer with a herb layer carpeting of
wildflowers, mosses and ferns. Leaves and fallen limbs and debris
slowly decompose and return nutrients back to the soil.
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Wildflower groundcover grows early in spring before shade from
canopy develops
Tree leaves are broad and flat for very efficient
photosynthesisTrees are deciduous and drop their leaves in
fall/winter to prevent water loss and snow damage Trees have
developed thick protective bark to insulate from winter
freezing
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Aquatic Adaptations of Plants - In some environments plants may
be partially or completely submerged in water. An aquatic
environment changes many physical and anatomical requirements that
terrestrial plants have in order to survive.
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Submerged plants lack an effective vascular transport system in
the stems. Instead water, dissolved gases and nutrients are
provided by simple absorption into the leaves. Stems and leaves of
underwater plants are flexible to move with currentsRoot system
with root hairs are much reduced. Root primary function may be for
anchorageLeaves and stems may develop aerenchyma tissue. This is
parenchyma tissue that develops many air spaces or gaps presumably
for gas exchange or for floating leaves or stems.Floating leaves
will have chlorophyll tissue in upper surface of the leaf.
Additionally, stomates may be primarily or totally on the upper
surface of the leaf
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There are three basic plant cell types that are recognizd:
parenchyma, collenchyma and sclerenchyma. For the most part the
classification is based on the extent that secondary cell wall
material has been deposited and whether the cells are living when
they reach their mature state.
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Collenchyma has secondary cell wall deposits in the corners of
the cell or along parallel walls. These thickenings provide
additional support to the young herbaceous plant stem. All
collenchyma is located near the periphery of the stem, never in the
center and usually is in patches of tissue. In comparison to
parenchyma the cells are usually much smaller. Like parenchyma
cells these cells are living at maturity.
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4. Observe collenchyma cells from a section of a young plant
stem under the second microscope.
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Sclerenchyma cells form a variety of cell types and tissues.
Note the much thicker cell walls due to secondary cell wall
deposition
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DNA Transcription - For a gene from the chromosome to be
activated the DNA that codes for it must first be transcribed from
the DNA (template) to messenger RNA (mRNA). This copy of the DNA is
then used to build proteins which direct the expression of the
gene. In RNA uracil replaces thymine as one of the nucleotide
bases. An animated illustration of the process is found at the
following link:http://www.johnkyrk.com/DNAtranscription.html
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RNA Translation - The mRNA is next used as a template from which
specific proteins will be constructed through the action of
ribosomes and transfer RNA (tRNA).
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Genetics - Earlier this semester some Rapid Cycling Brassica
plants where crossed where the parents were Non-Purple Stemmed,
Standard Height (p/p, T/T) x Purple Stem, Rosette-Dwarf (P/P, t/t)
to produce plants that had a heterozygous genotype (Pp, Tt). If
these seeds were planted what phenotype(s) would you expect the
offspring to be? Phenotype = All Purple Stem and Standard
Height
Genotype = all PpTt
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If we cross two of the F1 offspring what are the possible
combinations?
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So we need to set up our Punit square. First we determine the
possible gametes of the parents and put those in along the sides of
the square. Then we work out the possible combinations