Question

the can contain viruset Unless you need to fer to stay in Protected View Erable Editing Is a plant hormone/what is the function of a plant hormone? What are the three general steps of a signal transduction pathway? They include (1) reception, (2) transduction (3) Where does each of the three steps above take place? List each one individually. What happens at each step: during which of the three steps is a receptor protein activated? Which of three relies on secondary messengers? To what types of stimuli do plants respond? • What do these three plant hormones do: auxin, cytokinins, ethylene. • What is a tropism? Example? What's the difference between a positive tropism and a negative? What is the acid growth hypothesis of cell elongation? Which hormone is involved? What are the three steps? What do the enzymes expansins do? When plants take in ions during this process... the cell elongates ... Why? What is the driving force of this elongation? What are the three responses that plants have during the Triple Response to Mechanical Stress? What plant hormone is responsible for this response? What happens when the concentration of this hormone increases? We discussed a trade-off between height and thickness... What would a plant with a low concentration of the hormone look like and how would it differ from a plant exposed to a high concentration of the hormone?

Answer 1

1. Plant hormones as signal molecules regulate cellular processes in targeted cells locally and when moved to other locations of the plant. They also determine the formation of the root, stem, leaf, and flower and facilitate the shedding of leaves and the development and ripening of fruits.There are five hormones found in plants namely auxins, gibberellins, cytokinins, abscisic acid or ABA and ethylene.

2. Response.

3. These three steps take place in the process of cell signalling or communication.

Reception: A cell detects a signaling molecule from the outside of the cell. A signal is detected when the chemical signal (also known as a ligand) binds to a receptor protein on the surface of the cell or inside the cell.

Transduction: When the signaling molecule binds the receptor it changes the receptor protein in some way. This change initiates the process of transduction. Signal transduction is usually a pathway of several steps. Each relay molecule in the signal transduction pathway changes the next molecule in the pathway.

Response: Finally, the signal triggers a specific cellular response.

Once the target cell receives the signal molecule it converts the signal to a form that can bring about a specific cellular response. This often occurs in a series of steps called a signal transduction pathway. Signal molecules bind to receptor protein, in cell membranes, and generally cause a conformational change in the proteins. This change in conformation is transmitted to the cytoplasmic domain or part of the receptor molecule. The transformed molecule interacts with the information-relaying molecules in the cytoplasm. These molecules are small molecules present in the cytoplasm known as secondary messengers.

4. Plants are known to respond to a number of external stimuli like light, gravity, touch, chemicals, etc. Plants respond to the external factors with the help of receptors and hormones. The receptors help the plants to sense the external stimulus and act accordingly. They control the growth of plant in response to light.

5. During phototropism and gravitropism, the plant hormone auxin controls cell elongation. The plant hormone cytokinin promotes cell division, controling many developmental processes in plants. Ethylene serves as a hormone in plants. It acts at trace levels throughout the life of the plant by stimulating or regulating the ripening of fruit, the opening of flowers, and the abscission (or shedding) of leaves.

6. A tropism is a biological phenomenon, indicating growth or turning movement of a biological organism, usually a plant, in response to an environmental stimulus. Some examples of tropisms include gravitropism (response to gravity), hydrotropism (response to water), thigmotropism (response to touch), and phototropism (response to light). These tropisms are vital to plants' survival. Positive tropism is movement or growth towards a stimulus, whereas negative tropism is the movement or growth away from a stimulus.

7. Acid growth hypothesis states that auxin increases the activity of the proton pumps, which lowers the pH of the cell wall. This acidification of the wall activates enzymes called expansions that break the cross-links between cellulose microfibrils and other cell wall constituents, which loosens the cell wall's fabric. Auxins promote stem elongation, inhibit growth of lateral buds (maintains apical dominance). They are produced in the stem, buds, and root tips. Example: Indole Acetic Acid (IA). Auxin is a plant hormone produced in the stem tip that promotes cell elongation.

Plant cells are surrounded by cell walls, which are dynamic structures displaying a strictly regulated balance between rigidity and flexibility. Walls are fairly rigid to provide support and protection, but also extensible, to allow cell growth, which is triggered by a high intracellular turgor pressure. Wall properties regulate the differential growth of the cell, resulting in a diversity of cell sizes and shapes. The plant hormone auxin is well known to stimulate cell elongation via increasing wall extensibility. Auxin participates in the regulation of cell wall properties by inducing wall loosening. Here, we review what is known on cell wall property regulation by auxin. We focus particularly on the auxin role during cell expansion linked directly to cell wall modifications. We also analyze downstream targets of transcriptional auxin signaling, which are related to the cell wall and could be linked to acid growth and the action of wall-loosening proteins. All together, this update elucidates the connection between hormonal signaling and cell wall synthesis and deposition.

8. Ethylene is a phytohormone which protects seedlings from getting damaged during germination. Ethylene exhibits some influence on germinating seedlings. These responses are termed to be triple response. Ethylene causes what is known as the "triple response" in plants: it causes plants to have short shoots, fat shoots, and increased lateral root growth. In seedlings, ethylene also stimulates root hair production by the radicle.

Auxins promote stem elongation, inhibit growth of lateral buds (maintains apical dominance). They are produced in the stem, buds, and root tips. Example: Indole Acetic Acid (IA). Auxin is a plant hormone produced in the stem tip that promotes cell elongation.

Plant Hormone Stem Elongation Internode Length Tall Plant Dwarf Plant root growth and inhibits shoot growth of maize seedlings at low concentration and vice versa.