
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
EBK BIOLOGY
- Linkage in common bean Alleles at the P locus control seed color. Plants which are pp have white seeds, white flowers and no pigment in vegetative parts. Plants which are P_ have black seeds, purple flowers and may have varying degrees of pigment on stems and leaves. Seed color can be assessed, visually, based on if the seed is white or not white A gene for mold resistance has been reported and we want to determine its inheritance and whether it is linked to P. For the purposes of this exercise, we will assume that resistance is controlled by a single locus M, and M_ plants are resistant and mm plants are susceptible. Resistance can be measured, under greenhouse conditions, 2 weeks after planting, by injecting each seedling with a spore suspension. After two weeks, the seedlings can be rated as resistant or susceptible, based on whether or not tissue is actively sporulating. For this exercise we will use seed and data from the F10 generation of a recombinant inbred population…arrow_forwardAlleles at the P locus control seed color. Plants which are pp have white seeds, white flowers and no pigment in vegetative parts. Plants which are P_ have black seeds, purple flowers and may have varying degrees of pigment on stems and leaves. Seed color can be assessed, visually, based on if the seed is white or not white A gene for mold resistance has been reported and we want to determine its inheritance and whether it is linked to P. For the purposes of this exercise, we will assume that resistance is controlled by a single locus M, and M_ plants are resistant and mm plants are susceptible. Resistance can be measured, under greenhouse conditions, 2 weeks after planting, by injecting each seedling with a spore suspension. After two weeks, the seedlings can be rated as resistant or susceptible, based on whether or not tissue is actively sporulating. For this exercise we will use seed and data from the F10 generation of a recombinant inbred population produced using single seed…arrow_forwardcan you help? I think its B but not surearrow_forward
- Skip to main content close Homework Help is Here – Start Your Trial Now! arrow_forward search SEARCH ASK Human Anatomy & Physiology (11th Edition)BUY Human Anatomy & Physiology (11th Edition) 11th Edition ISBN: 9780134580999 Author: Elaine N. Marieb, Katja N. Hoehn Publisher: PEARSON 1 The Human Body: An Orientation expand_moreChapter 1 : The Human Body: An Orientation Chapter Questions expand_moreSection: Chapter Questions Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,... format_list_bulletedProblem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,... See similar textbooks Bartleby Related Questions Icon Related questions Bartleby Expand Icon bartleby Concept explainers bartleby Question Draw a replication bubble with two replication forks.blue lines are DNA single strands and red lines are RNA single strands.indicate all 3' and 5’ ends on all DNA single…arrow_forwardProvide an answerarrow_forwardQuestion 4 1 pts Which of the following would be most helpful for demonstrating alternative splicing for a new organism? ○ its proteome and its transcriptome only its transcriptome only its genome its proteome and its genomearrow_forward
- What did the Cre-lox system used in the Kikuchi et al. 2010 heart regeneration experiment allow researchers to investigate? What was the purpose of the cmlc2 promoter? What is CreER and why was it used in this experiment? If constitutively active Cre was driven by the cmlc2 promoter, rather than an inducible CreER system, what color would you expect new cardiomyocytes in the regenerated area to be no matter what? Why?arrow_forwardWhat kind of organ size regulation is occurring when you graft multiple organs into a mouse and the graft weight stays the same?arrow_forwardWhat is the concept "calories consumed must equal calories burned" in regrads to nutrition?arrow_forward
- 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




