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36 Cards in this Set

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  • Back
how much water makes up the chemical component of plants?
What is the role of water in plant physiology?
acts as a solvent, helps maintain plant form (keeps cells turgid, contibutes to cell elongaton), supllies H+5 for phtosynthesis, supplies some of the O2 needed for biosynthesis.
What happens to most of the water that enters a plant?
leaves via transpiration
what is the bulk of the dry weight of plants?
96& organic material: mostly carbohydrates some protein and nucleic acids
Are all the chemicals found in plants necessary for their survival?
no because plants absorb elemnets nonspecifically
What technique is used to determine if a particular chemical is essential?
hydrophobic culture- plants are grown in mineral solutions instead of soil and solutions must be aerated to provide roots with oxygen needed for respiration
What mineral deficiencies are the most common?
ntrogen, potassium, and phosphorous
which organisms can use N2 from the atmosphere?
anything but a eukaryote
What process converts N2 to a usable form? What enzyme does this?
What is the cost in terms of energy?
nitrogen fixation. Nitrogenase. very expensive
what is the nitrogen fixation reactoin?
N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16ADP + 16 Pi
Why is it expensive to produce fertilizer?
it requires the consumption of fossil fuels
Besides using fertilizer, how can protein yield in crops be maximized?
the incorpation of fixed nitogen into proteins by plants
why is protein yeild in crops important?
protein deficiency is the most common form of malnutrion. people in developiing countries eat most vegetarian diets.
Describe the general mechanism of signal transduction.
a stimulus is received by a specific receptor protein, the receptor is altered, sending a signal to the cell, small intracellualr molecules,second messengers, amplify and transfer the signal
What is a circulating chemical that acts on specific cells to change their function called? Is it an intercellular or intracellular messenger?
hormone, Intracellular
What is the job of an intracellular messenger?
amplify and transfer the signal
what is any growth in a plant that resulls in a curvature toward or away from a stimulus called?
what is the growth of a shoot towards light called?
Describe the first experiment published to show that plants respond to stimuli. Who did it?o If a grass seedling is illuminated from one side, what happens?
Observing the response of plant seedlings to light. darwin and his sons.cells on the dark side grow faster than cells on the brighter side, the tip of grass seedling sense light.
Describe an experiment that demonstrates the presence of a mobile chemical that responds to outside stimuli.
the signal is a light activated mobile chemical. the respinse occured only when the tip was serperated by a permeable barrier.
what is the term used to describe a group of hormones that have multiple effects on plants?
what is known abou the functions of auxins?
most prominent response- elongation of cells within young developing shoots. Inhibits growth
what is the acid growth hypothesis?
1. activates enzyems called expansions. breaks the cross links between cellulose
2. allows more water to flow in -increse turgor
3. enables the cell to elongate
What is the connection between auxins and dioxin?
agent orange is a 50/50 mix of 2 synthetic auxins and it also contains dioxin
Why can auxins be used as herbicides?
induce rapid, uncontrolled growth. Eliminiate broad leafed weeds like dandelions.
what is the selecting and breeding of individuals that possess desired traits?
artifical selection
how is artificial seletion different from genetic engineering?
artifical selection is limited to the transfer of genes between closely related species. genetic engineering allows for process to be done quickly and directly.
describe the bt toxin and its impact on modern agriculture.
it becomes toxic in the gut of insects. High acidity of vertebrates stomachs render it harmless. Greatly reduces the use of chemical insecticides in thes crops.
what is golden rice and what is its potential impact on 3rd world countries?
A trangenic variety of rice with 3 daffodil genes, it increase vitamen A levels in rice. there is a deficiency in beta carotene (vitamin a) which can lead to decreased resistance to infection and blindness whch is common in developing countries
what is an example of a risk that a GM crop might pose?
potential transfers of allergenbs from the gene source to the food crop.
how can the risks in genetic engineering be moinimized?
extensive field testing before their use as commercial crops is neccessary
what is the risk of transgene escape? what research is occuring to prevent this?
The transfer of introduced genes into related weeds. COuld produce super weed. efforts are underway to breed male sterility into transgene crops.
how can you ensure that you have accurate reliable information about a scintific topic?
consider the source, look for information in peer reviewed journals fist, reputable news publications, consider date of publication,
atmospheric nitrogen must be converted to what for plants/
ammonium NH+4 or nitrate NO-3(most readily absorbed)
the natural auxin plants, and is most poten, first plant hormone discovered
IAA indolacetic acid
acidification of the wall activates these enzymes