DPBioY2 - 2020 - 9.3 Plant Growth
DPBioY2 - 9.3 Plant Growth
2 marks for your questions
3 marks for your reply
2 marks for submitting by July 16th, 2020
DPBioY2 - 2020 - 5.3 & 5.4 Classification and Biodiversity & Cladistics
DPBioY2 - 2020 - 5.3 & 5.4 Classification and Biodiversity & Cladistics 2 marks for your questions 3 marks for your reply 2 marks for submitting by
1. What is the simplified biochemical process of how the Auxin hormone promotes shoot growth and inhibited root growth.
ReplyDelete2. How do the PIN3 move auxin to the shaded side of the leaf? Having trouble visualizing it.
3. How do the additional meristems form from the initial apical meristem
For your third question, The way I visualize the addition of meristems is in pruning. If you dont know pruning is trimming a plant so, it grows in the way you want. the more pruning the more bushier a plant becomes. Plants have dormant buds in case a meristem goes out, when the primary meristem is growing there is no need to grow out because the plant encouraged to put all of its resources in rightfully growing towards the sun. Agriculturist cut the tips of fruiting trees to make them become wind sturdy and focus in growing mass instead of height. By cutting the primary meristem four buds may come out of dormancy to take the place of primary stem thus becoming four individually new meristems. I encourage you to watch this video on pruning it shows the natural plant response of loosing a primary meristem as well as the benefits.
Deletehttps://www.youtube.com/watch?v=ERfrZw9HFrA
For your second question, auxin is moved to the other side of the leaf through sap via the phloem or through the surface of a cell.https://dev.biologists.org/content/136/16/2675
Delete1. What would happen if meristems were located in leaves or flower petals rather than at the tips of shoots and roots?
ReplyDelete2. Has synthetic auxin been made? If it has, are they able to change the efficiency in them?
3. How do auxin move through the plant?
To answer your third question there are 2 ways for auxin to move throughout the plant, it passes in the sap and moves through the phloem where it is made and goes to a sink. The second is from cell to cell, it can enter a cell through diffusion or influx transporters and leaves the cell through efflux transporters (PIN proteins).
DeleteFor more info:
https://www.biology-pages.info/A/Auxin.html#:~:text=Auxin%20moves%20through%20the%20plant,(e.g.%2C%20the%20root).&text=at%20the%20lateral%20surface%20of,to%20mediate%20phototropism%20and%20gravitropism).
In regards to your first question, Most if not all plants have meristems this stem is just the dominant stem from creation. If a meristem was "misplaced" it wouldn't have the hormone availability to out compete higher sites of grow because a plants goal is to produce food to eventually reproduce. The main method of obtaining food in plants is photosynthesis so, a plant will likely produce hormones/supply a viable bud or other meristem that have a higher availability of sun light. By the way plants have multiple meristems so if it looses/hypothetically misplaced one it will pull lateral buds out of dormancy or rely on other branches. I think it impossible due to the growth progress but I hope this helps.
DeleteFor your second question,
DeleteYes, synthetic auxin had been made and is used in herbicides to kill and control weeds. Because of this, they had to make the auxin more efficient to kill the plant instead of helping it grow by, "It seems, however, that the primary action of these herbicides is likely to affect cell wall plasticity and nucleic acid metabolism. Synthetic auxins also affect protein synthesis, cell division and growth, and stimulate ethylene evolution, which may in some cases produce the characteristic epinastic symptoms associated with exposure to these herbicides".
http://herbicidesymptoms.ipm.ucanr.edu/MOA/Synthetic_Auxins/
1. How many types of Auxin are there?
ReplyDelete2. How does a high concentration of IAA inhibit growth if it also promotes elongation in the stem?
3. What are cytokinins and what is their role in the roots?
Regarding your first question, The short answer is that there are 5 types of natural occurring auxins found in plants. The names are as follows: indole-3-acetic acid, 4-chloroindole-3-acetic acid, phenylacetic acid, indole-3-butyric acid, and indole-3-propionic acid keep in mind the chemical structures are diverse as seen in the names. There are also synthetic auxin variants that are still being created in addition the synthetic molecules induce auxin present effects so their "auxin like" not formally auxin because auxin is natural. The most influental auxin variant in consideration of our studies in plant phototropism is indole-3-acetic acid which is natural occurring. My second link goes more in-depth with the structures and identification of auxin compounds.
DeleteMy sources:
https://www.britannica.com/science/auxin
https://irrecenvhort.ifas.ufl.edu/plant-prop-glossary/01-biology/01-hormones/02-hormones-auxin.html
To answer your third question, cytokinins are a family of plant hormones. They are produced in the apical meristem and travel upwards through the xylem. Cytokinins have a vital role when it comes to plant growth and development. They help with embryogenesis, maintenance of root and shoot meristems, and vascular development. They also modulate root elongation, lateral root number, etc.
DeleteHere is a good article which details ample information about cytokinins.
https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-015-0214-5
For your second question, it seems as though high concentrations of auxin stimulate ethylene production which is the main factor of inhibiting the growth. Ethylene is harmful to plants as it accelerates the aging process of the plant.
Deleteresearch:
https://www.researchgate.net/post/Why_does_too_much_auxin_content_inhibit_leaf_expansion#:~:text=Most%20recent%20answer&text=High%20concentration%20of%20auxin%20above,and%20consequently%20ethylene%20inhibits%20growth.
https://www.catalyticgenerators.com/ethylene-c2h4/#:~:text=While%20ethylene%20is%20invaluable%20due,product%20quality%20and%20shelf%20life.
1.Can plants receive stem cell treatment via totipotent cells? If so in what circumstances?
ReplyDelete2.In what ways does phototropism or the amount of light impact gene expression in plants?
3.If auxin is produced in the apical meristems of plants, what would happen if the apical meristem was cut off, Would a plant be able to orient its self towards the light by other means or would the lateral buds take over?
For your second question, a light absorbing pigment called chromophore can lead to an impact on gene expression. When it receives light, it can change the shape of the protein which chromophore is linked to, and the shape change results in an alteration of activity and starts a signaling pathway. The signaling pathway then responds to the light it receives, and one of the responses includes a change in gene expression.
DeleteHere is the source:
https://www.khanacademy.org/science/biology/plant-biology/plant-responses-to-light-cues/a/phototropism-photoperiodism
For your third question, if the apical meristem was cut off, the plant would cease growth with the exception of the lateral bud growth. It would cause the plant to grow in more of a bush-like manner.
Deletehttps://www.topperlearning.com/answer/what-will-happen-if-apical-meristem-is-damaged-or-cut/z7njbeqff
https://www.quora.com/What-happens-if-the-apical-meristem-is-destroyed-or-cut-in-a-plant
For your first question, through my research it seems as though plants cannot receive stem cell treatment, however plant cells can be used as a stem cell therapy in humans. As far as the need for plants to receive stem cells goes, other processes such as micropropagation have the ability to remove things such as viruses.
DeleteHere's more info on the stem cell treatment in humans:
http://stemcell101.com/how-plant-stem-cells-work-when-used-as-stem-cell-therapy-in-humans/#:~:text=(1)%20plants%20have%20stem%20cells,healing%20and%20wellness%20in%20humans.
- Is micropropogation basically just cloning? What are the differences between both?
ReplyDelete- How can the concentration of auxins inhibit or promote growth?
- What is meant by indeterminate growth?
- What are the differences in differentiation in plant cells as opposed to animal cells?
- Do plants have an immune system?
- How do viruses impact plants?
- Explanation as to how auxin efflux pumps work?
To answer your third question indeterminate growth is when the plant stem will grow indefinitely without being stopped by a terminal inflorescence (flower/bud) or some other reproductive structure. Determinate growth is when the main stem ends with a bud or reproductive structure.
Deletehttps://www.merriam-webster.com/dictionary/indeterminate%20growth
To answer your first question,
DeleteCloning regarding animals and humans have been done with adverse effects. Almost all of this type of cloning occurs by fusing the nucleus of a mammary-gland cell into an enucleated egg cell. With totipotent cells, they can only form a new organism when implanted in a utero. If not, it leads to unorganized growth that results in tumors and eventually death. In this instance with micropropagation, I think it would be more comparable to stem cell research and not cloning per say.. In the case of the plants, tissue made of undifferentiated cells are isolated and put into a median to continue replicating. A unique feature of plants is that most plant cells, even including fully differentiated types, have the capacity to generate whole plants due to their cells being totipotent. Plants also do not require a utero to be present and can continue to differentiate to form a whole new plant. This is a feature not seen in humans or animals regarding cloning.
Sources: https://www.sciencedirect.com/topics/medicine-and-dentistry/totipotent-stem-cell
^ Sorry that was me.
DeleteFor the fifth question no plants dont have immune systems as they mainly rely on the immunity of each cell and signals that emit from infection sites.
DeleteMore info: https://www.nature.com/articles/nature05286#:~:text=Plants%2C%20unlike%20mammals%2C%20lack%20mobile,sites1%2C2%2C3.
For your sixth question, depending on what virus, most plant viruses are transmitted by insects. when an insect causes damage to a plant,a virus can get in to then ruin a plants defences and ultimately make them weak enough to end up dying.
DeleteTo add onto your sixth question,
DeleteAfter the insects transmit the virus, the virus takes over the nucleus like it does in animal cells, and creates a bunch of copies of itself until it takes over the entire plant and dies.
This website breaks it down well:
https://www.the-scientist.com/infographics/how-viruses-attack-plants-30340#:~:text=Most%20plant%20viruses%20are,while%20evading%20the%20plant's%20defenses.
In regards to your seventh question, auxin efflux pumps are distributed to the shaded sides of the plant. When this happens, a high auxin concentration is built up on that side. This build up causes the cells on that side to swell from the water being accumulated inside the vacuoles of the cells on that side. The swelling causes elongation on that side, which bends the shoot in the direction of the light. This website provides a better explanation of this process if you'd like more information:
Deletehttps://www.mrgscience.com/topic-93-growth-in-plants.html
For your second question, the auxin is mostly used as a promoter hormone in plants because it elongates cells. However, anything can be harmful in high concentrations, so with high concentrations of auxin, it can stimulate ethylene production. Ethylene can be harmful to plants because it speeds up the aging process of plants.
Deleteresearch:
https://www.researchgate.net/post/Why_does_too_much_auxin_content_inhibit_leaf_expansion#:~:text=Most%20recent%20answer&text=High%20concentration%20of%20auxin%20above,and%20consequently%20ethylene%20inhibits%20growth.
https://www.catalyticgenerators.com/ethylene-c2h4/#:~:text=While%20ethylene%20is%20invaluable%20due,product%20quality%20and%20shelf%20life.
Are the different stages of undifferentiated cells the same as in animals?
ReplyDeleteTo clarify, the shoot grows because more water fills up the vacuole, making it larger and stretching out the cell wall?
What is the purpose of auxin in cell elongation?
How does lateral meristem growth occur?
How can too much auxin concentration cause it to inhibit growth instead of promote it?
What makes intermediate growth possible?
To answer your third question auxins are a type of hormone that is made in the stems, buds, and root tips. This type of hormone promotes stem elongation and inhibits the growth of buds, auxin will move to the darkest side of the plant and make those cells grow larger than the cells on the lighter side. Which causes for the plant to curve towards the sunlight (phototropism).
Deletehttps://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookPLANTHORM.html#:~:text=Auxins%20promote%20stem%20elongation%2C%20inhibit,buds%20(maintains%20apical%20dominance).&text=Auxin%20is%20a%20plant%20hormone,lighter%20side%20of%20the%20plant.
To answer your first question,
DeleteThe totipotent stem cells seen in plants are analogous to totipotent stem cells in animals. There is an exception in which plants have a confined region of growth and development. The totipotent stem cells in plants found in the meristem also have the capability to grow an entirely new plant if isolated due to their property of confined region and growth. Although they are the same in totipotent nature, human cells must be implanted in a utero due to there being proper conditions and timing. When human totipotent stem cells are implanted at sites other than the utero, cells can differentiate in an unorganized fassion leading to teratocarinomas (big tumors).
https://ib.bioninja.com.au/higher-level/topic-9-plant-biology/untitled-2/meristems.html
For your fifth question,
DeleteThe exact workings of auxin or if there are other hormones in play have not been entirely satisfactorily explained. In fact, there are 9 theories on how inhibition could occur revolving around the talking point whether the inhibition is due to the auxin itself or to some effect of auxin on the production or movement of other substances. Generally speaking, The application of very high concentrations of auxin inhibits the growth of shoots directly. High concentrations slow the rate of protoplasmic streaming are at a range where the substances are deemed toxic.
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4246732/
For your last question, indeterminate growth is possible just because there is no predetermined structure like there is with determinate growth. With no set structure to stop growing at, it just continues to grow until its killed by an external factor.
DeleteTo Answer the fourth question Lateral Meristem works by having two possible ways it can grow through the vascular cambium and the cork cambium. The vascular cambium produces secondary xylem and phloem for the plant. It also has its own set of hormones that control growth, regulation, and maintenance activities in the tissue. The Cork give rise to the periderm, periderm is a corky outer layer of a plant stem formed in secondary thickening or as a response to injury or infection, the periderm replaces that epidermis to produce bark. The bark acts like a shield for the plant. This is typically made of three layers, The phelloderm is the innermost layer, on top of that layer is the cork cambium lastly is the bark.
Deletehttps://biologydictionary.net/lateral-meristem/
https://biologydictionary.net/meristem/
This comment has been removed by the author.
DeleteFor your second question,
DeleteThe shoot grows because when auxin binds to the receptor, a proton pump in the plasma membrane of the plant cell secretes hydrogen ions into the cell wall. The pH of the cell wall decreases, resulting in cellulose fibres to break bonds between them, creating more elasticity of the cell wall. It allows cellular expansion as water fills up the vacuole, because the cell is more flexible.
https://ib.bioninja.com.au/higher-level/topic-9-plant-biology/untitled-2/auxin.html
1. What are all the differences between protoderm, procambium and ground meristem in regards to structure as well as function?
ReplyDelete2. Why can a high concentration of IAA inhibit growth? What is the molecular explanation for this?
3. What are all the different types of tropisms and in what way do each of them affect the growth of the plant?
4. Can somebody help clarify exactly how auxin concentration in certain areas of the plant inhibits or promotes elongation?
5. Can micropropagation be used for any plants or are there some that cannot be used for this purpose? What are the requirements, if any, for the plant in order for it to be able to undergo this process?
6. What other things can cryopreservation be used for?
To Answer the third question, Forms of tropism include phototropism; response to light Growth toward light. Geotropism; response to gravity, it directs root growth toward the pull of gravity (positive gravitropism) and stem growth in the opposite direction (negative gravitropism). chemotropism; response to particular substances. With this one plant roots may exhibit positive thermotropism in one temperature range and negative thermotropism in another temperature range. hydrotropism; response to water, this works through protection against drought conditions through positive hydrotropism and against water over-saturation through negative hydrotropism. thigmotropism; response to mechanical stimulation Positive thigmostropism is demonstrated by climbing plants or vines, which have specialized structures called tendrils. A tendril is a thread-like appendage used for twinning around solid structures
Deleteand
. I may have missed one
For your last question,
DeleteCyropreservation can be used for any type cell whether it be plant or animal. This means that it can be used for human stem cells, organ transplants, embryo storage, etc.
For more info. here's the website I used:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5395684/#:~:text=Cryopreservation%20is%20a%20process%20that%20maintains%20biological%20samples%20in%20a,the%20fine%20structure%20of%20cells.
To answer your 4th question,
DeleteA higher concentration of auxin leads to a promotion of elongation because as the auxin binds to the cell's auxin receptor, hydrogen ions are secreted into the cell walls which loosen connections between cellulose fibers, allowing cell expansion.
1. Can someone clarify what the process of Micropropagation is and how that can be applied to science or even the medical field if possible?
ReplyDelete2. Can a plant live without Auxin?
3. Can Auxin be synthetically produced? If so can we use that on farms and other crops? what are the side effects if any?
4. Can the method of coral transplantation be applied to other plants?
For your first question,
DeleteMicropropagation has four stages. Initiation stage: First, a part of the plant(explant) is cut off of the plant then its surface is decontaminated to create an aseptic culture which allows only microorganisms that are not harmful to the plant to survive. Then the plant is put in agar. Multiplication stage: Second, cytokinin is placed in the agar because it induces the growth of shoots and plant cells.
Preplant Stage: Third, to further induce shoot growth they may also add an auxin to the agar.
Acclimatization stage: Fourth, once the shoot has developed roots it is removed from the culture and planted in the soil. It also says that humidity affects if the micro propagated plants wilt because they are susceptible to it. The humidity will have to be gradually reduced in its in vitro environment in the soil.
It can be applied to sciences like Conservation Biotechnology. Scientists use micropropagation to preserve threatened plant species, restore damaged environments by planting more plants.
Micropropagation applies to the medical field as it conserves the genotypes for critical medicinal plants and maintain the plants efficiency of active ingredients. It also allows the mass production of medicine because many of the cloned explants can be produced from one plant. Some medicinal plants that are mass produced by micropropagation are "Catharanthus roseus (Apocynaceae), Chlorophytum borivilianum (Liliaceae), Datura metel (Solanaceae), and Bacopa monnieri (Scrophulariaceae)".
http://www.biotech.iastate.edu/publications/lab_protocols/AV_Micropropagation.html#:~:text=Micropropagation%20is%20the%20aseptic%20culture,pieces%20of%20tissue%2C%20or%20organs.&text=The%20process%20of%20micropropagation%20can,c)%20placed%20on%20a%20medium.
http://www.omahazoo.com/rare-plant-research
https://pubmed.ncbi.nlm.nih.gov/16472132/
For your second question, it seems that all plants have auxin. Since it plays a crucial role in cell elongation, cell division, as well as inhibiting growth when necessary, plants without auxin would probably not be able to live.
DeleteHere is a website that explains the importance of auxin:
https://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookPLANTHORM.html
For your 3rd question,
DeleteWe can synthetically create auxins. Synthetic auxins have similar properties to natural auxins.
https://link.springer.com/article/10.1007/s10725-013-9867-7
1. Why does auxin take effect on plant cells away from the light source?
ReplyDelete2. Do leaves and shoots grow at the same rate?
3. How do plants grow in response to artificial gravity?
4. Does a plant have a system similar in function to the central nervous system, in which plant parts can communicate with each other?
5. Is micropropagation used to create biomes in zoos?
For your 5th question,
DeleteAt OmahaZoo, researchers use micropropagation in restoration projects.
http://www.omahazoo.com/rare-plant-research
In regards to your fourth question: yes! It is necessary for plant parts to communicate with one another for the survival of the whole plant. Here is an article I found to explain further: https://phys.org/news/2016-02-benefit.html
DeleteTo answer your first question,
DeleteI think that the auxins moves to the shady side of the stem so it can grow torwards the sun. Here is the source I used: https://journeynorth.org/tm/tulips/AuxinsGrowth.html#:~:text=Under%20normal%20light%20conditions%20auxins,it%20bends%20toward%20the%20light.
To answer your first question, it is not fully known exactly why auxin is unevenly distributed the way that it is, but it is known that it has something to do with the different levels of phototropin activation. Phototropin molecules absorb light on the side of the plant that is illuminated, which causes them to change shape and become active. Their activity affects the activity of other proteins in the cell, but it is unclear exactly how this affects the auxin efflux pumps exactly. If you'd like a better explanation and visualization of this, I recommend this website:
Deletehttps://www.khanacademy.org/science/biology/plant-biology/plant-responses-to-light-cues/a/phototropism-photoperiodism
In answer to your second question leaves and shoots do not grow at the same rate and the rate varies depending on the amount of resources which the plant recieves.
Delete1. Are there other hormones like auxin that cause growth in plants?
ReplyDelete2. Could someone explain the IAA protein to me?
3. Why does auxin travel down the plant? Why is the terminal bud at the top of the plant?
For your first question,
DeleteThere are four other major hormones that cause growth: gibberellins, cytokinins, ethylene, and abscisic acid.
https://www.nutrienagsolutions.ca/about-cps/news/plant-hormones#:~:text=There%20are%20five%20major%20types,and%20shoots%20and%20reduce%20stress.
In regards to your second question, the IAA protein (in my understanding) acts as an repressor to the transcription factor. When auxin binds to the IAA protein, it releases the transcription factor which then makes more auxin by transcribing the necessary gene to do so.
DeleteTo answer your second question,
DeleteThe IAA is a protein that controls the gene expression of the auxin and what it can do. The website I found describes it as a "regulator."
Here is the website I found if you would like to look at it: https://www.ebi.ac.uk/interpro/entry/InterPro/IPR003311/
1.What is an external Stimuli?
ReplyDelete2. Why does the Auxin move to the opposite sight of the growing shoot when the light stimulus is from one direction?
This was Joelle Zipp^
DeleteIn regards to your first question, an external stimuli is anything that occurs in the outside environment around the organism that causes, or stimulates, a response from the organism.
DeleteIn answer to your second question the Auxin moves from the opposite side of the growing shoot when the light is on that side in order to curve the plant in the direction of the light in order to gain more light energy for the plant.
Delete1. How was auxin discovered?
ReplyDelete2. Where does the initial auxin needed in the first cells to enable the auxin gene come from? Is there a small amount in the seed?
To answer your first question,
ReplyDeletethe auxin was discovered by Fritz W. Went and he was able to isolate the auxin that came from oat coleoptiles and put it in a gelatin block. Here is the source I used if you would like to read more.
1. Are coleoptiles produced among every axillary bud?
ReplyDelete2. Can plants only have up to two xylem and phloem or can they have a multitude of them? If so, how many is the max?
3. Could you use some aspects of micropropagation to erase a virus from a plant?
4. What's the most common use for micropropagation?
In answer to your 4th question micropropagation is most commonly used to create many progeny plants at a very rapid rate.
DeleteTo answer your third question, Although there are virtually no antiviral compounds available to cure plants with viral diseases, efficient control measures can greatly mitigate or prevent disease from occurring.
DeleteSorry about the late response
ReplyDelete1. What happens when microarrays are damaged?
2. What is the use of the meristem in the plant?
3. Can Auxins be damaged to where they dont stop initiating plant growth or fruit development.
To answer your second question, The apical meristem, is an undifferentiated meristematic tissue found in the buds and growing tips of roots in plants. Its main function is to trigger the growth of new cells in young seedlings at the tips of roots and shoots and forming buds.
DeleteTo answer your third question, the closest thing I could find is that Auxins can be produced naturally (by the plant) or synthetically (in a lab). When produced synthetically, they can be used in high concentrations as a pesticide, causing drastic growth. The herbicide, 2-4-D, is an example of an auxin-based pesticide, specifically engineered to cause dicots (plants like dandelions) to grow quickly and uncontrollably, ultimately killing the plant.
DeleteI apologize for the late response,
ReplyDelete1) What experiments have been run to test Gavitropism?
2) Where are efflux transporters located in the cell?
3) What other common plants (besides orchids) are produced using Micropropaganation? and have there been any negative side affects?