
Introduction: Plant hormones are chemical molecules produced by plants in extremely low concentration for regulating the growth and development. There are five major hormones involved in the growth process. They are auxin, gibberellin, ethylene, abscisic acid, and cytokinin. Each of these hormones has its own functions at specific locations. The presence of these hormones in a definite amount is very essential for the normal growth and development of the plant.

Answer to Problem 1TYU
Correct answer: In the signal transduction process for the hormone auxin, the molecule ubiquitin tags certain proteins for destruction.
Hence, the correct answer is option (c).
Explanation of Solution
Reason for the correct answer:
General mechanism of action of auxin hormone:
Auxins are a group of related hormones responsible for a wide range of consequences on the growth and development of plants. Within a certain concentration, Auxin stimulates cell elongation in stems and coleoptiles. Auxin inhibits elongation growth by increasing the cell wall extensibility, according to the acid growth hypothesis. The main effects of auxin are to promote cell elongation according to the concentration.
Many plant hormones bind to the receptors which trigger the enzymatic reaction and results in the changes for cell growth and development of the plants. Both external and internal signal triggers the auxin hormone synthesis. The cytosol or the nucleus of the cell contains one receptor with three-dimensional shape (TIR1 receptor) that binds to auxin molecule. As the auxin binds to its receptor, ubiquitin molecule attaches to the repressor molecule and inhibits the auxin response genes. Thereafter, the ubiquitinylated protein is targeted and degraded into peptide fragments in a proteasome. This causes transcription of auxin response gene which acidifies the cell wall of target cells. The acidified target cell walls become more plastic which enables it to expand due to increased force of the cell’s turgor pressure. Thus, the action of auxin hormone causes cell expansion without cell division.
Option (c) is given as “tags certain proteins for destruction”.
The small regulatory protein called ubiquitin attaches to other proteins and are used to tag certain proteins for destruction. This process of tagging is referred to as ubiquitination and it is a post-translational modification. Ubiquitin-mediated proteolysis normally takes place during auxin signaling in plants.
Hence, the correct answer is option (c).
Reasons for the incorrect answers:
Option (a) is given as “absorbs blue light”.
Phototropins are the proteins that absorb blue light and they help to control the photosynthetic efficacy of plants, not auxins.
Hence, option (a) is incorrect.
Option (b) is given as “becomes phosphorylated”.
Phototropins are the blue-light receptors that control the photosynthetic efficacy of plants located at the shoot tips. These proteins become phosphorylated in response to blue light.
Hence, option (b) is incorrect.
Option (d) is given as “interacts antagonistically with gibberellins”.
Gibberellin is a growth-regulating hormone that enhances the elongation of stems and leaves and in the development of fruits. During auxin signaling in plants, the ubiquitin molecule does not antagonistically interact with gibberellins. Instead, ubiquitin-mediated proteolysis takes place in the signal transduction process in auxin.
Hence, option (d) is incorrect.
Option (e) is given as “binds to a receptor in the plant cell’s plasma membrane”.
During auxin signaling in plants, the ubiquitin molecule does not bind to a receptor in the plasma membrane of the plant cell. Instead, ubiquitin-mediated proteolysis takes place in the signal transduction process in auxin.
Hence, option (e) is incorrect.
Hence, options (a), (b), (d), and (e) are incorrect.
As the auxin binds to its receptor, ubiquitin molecule attaches to the repressor molecule in order to target it for destruction.
Want to see more full solutions like this?
Chapter 38 Solutions
Biology (MindTap Course List)
- Participants will be asked to create a meme regarding a topic relevant to the department of Geography, Geomatics, and Environmental Studies. Prompt: Using an online art style of your choice, please make a meme related to the study of Geography, Environment, or Geomatics.arrow_forwardPlekhg5 functions in bottle cell formation, and Shroom3 functions in neural plate closure, yet the phenotype of injecting mRNA of each into the animal pole of a fertilized egg is very similar. What is the phenotype, and why is the phenotype so similar? Is the phenotype going to be that there is a disruption of the formation of the neural tube for both of these because bottle cell formation is necessary for the neural plate to fold in forming the neural tube and Shroom3 is further needed to close the neural plate? So since both Plekhg5 and Shroom3 are used in forming the neural tube, injecting the mRNA will just lead to neural tube deformity?arrow_forwardWhat are some medical issues or health trends that may have a direct link to the idea of keeping fat out of diets?arrow_forward
- Can I please get this answered with the colors and how the R group is suppose to be set up. Thanksarrow_forwardfa How many different gametes, f₂ phenotypes and f₂ genotypes can potentially be produced from individuals of the following genotypes? 1) AaBb i) AaBB 11) AABSC- AA Bb Cc Dd EE Cal bsm nortubaarrow_forwardC MasteringHealth MasteringNu × session.healthandnutrition-mastering.pearson.com/myct/itemView?assignment ProblemID=17396416&attemptNo=1&offset=prevarrow_forward10. Your instructor will give you 2 amino acids during the activity session (video 2-7. A. First color all the polar and non-polar covalent bonds in the R groups of your 2 amino acids using the same colors as in #7. Do not color the bonds in the backbone of each amino acid. B. Next, color where all the hydrogen bonds, hydrophobic interactions and ionic bonds could occur in the R group of each amino acid. Use the same colors as in #7. Do not color the bonds in the backbone of each amino acid. C. Position the two amino acids on the page below in an orientation where the two R groups could bond together. Once you are satisfied, staple or tape the amino acids in place and label the bond that you formed between the two R groups. - Polar covalent Bond - Red - Non polar Covalent boND- yellow - Ionic BonD - PINK Hydrogen Bonn - Purple Hydrophobic interaction-green O=C-N H I. H HO H =O CH2 C-C-N HICK H HO H CH2 OH H₂N C = Oarrow_forwardFind the dental formula and enter it in the following format: I3/3 C1/1 P4/4 M2/3 = 42 (this is not the correct number, just the correct format) Please be aware: the upper jaw is intact (all teeth are present). The bottom jaw/mandible is not intact. The front teeth should include 6 total rectangular teeth (3 on each side) and 2 total large triangular teeth (1 on each side).arrow_forward12. Calculate the area of a circle which has a radius of 1200 μm. Give your answer in mm² in scientific notation with the correct number of significant figures.arrow_forwardarrow_back_iosSEE MORE QUESTIONSarrow_forward_ios
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage LearningBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxBiology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning
- Biology: The Unity and Diversity of Life (MindTap...BiologyISBN:9781337408332Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa StarrPublisher:Cengage Learning




