Lab Practicum Review. What 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 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”?
Metabolism …….. the equation
What is a cambium and what does it do in a plant stem?
The plant cell verses animal cell…differences
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
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)
are setup around the lab. Examine each and find the features
common to stems and how they have been modified
from “normal” stems.
broadleaf dicots (lower figure)
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).
Insect pollination is responsible for producing 80% of the fruit and vegetables we consume. Wind, water and animals also help to transfer pollen.
Seed dispersal often requires “new ground” which can could be as simple as a field that has been plowed or a newly formed volcanic island
In 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.
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.
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.
Most of the earth’s 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.
Additionally, there is dispersal by animals after they eat the fruit, seeds that hitchhike by attaching to clothing or fur
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.
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.
The diagrams below show the chemistry of this conversion. Note that in alcoholic fermentation CO2 is produced, but not in lactic acid fermentation.
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:
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.
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.
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.
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.
4. Observe collenchyma cells from a section of a young plant stem under the second microscope.
Sclerenchyma cells form a variety of cell types and tissues. Note the much thicker cell walls due to secondary cell wall deposition
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 uracilreplaces thymine as one of the nucleotide bases. An animated illustration of the process is found at the following link:
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).
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
what are the possible combinations?
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