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 LL VERSION + MINDTAP V2.0(2 TER
- Draft a science fair project for a 11 year old based on the human body, specifically the liverarrow_forwardYou generate a transgenic mouse line with a lox-stop-lox sequence upstream of a dominant-negative Notch fused to GFP. Upon crossing this mouse with another mouse line expressing ectoderm-specific Cre, what would you expect for the phenotype of neuronal differentiation in the resulting embryos?arrow_forwardHair follicle formation is thought to result from a reaction-diffusion mechanism with Wnt and its antagonist Dkk1. How is Dkk1 regulated by Wnt? Describe specific cis-regulatory elements and the net effect on Dkk1 expression.arrow_forward
- Limetown S1E4 Transcript: E n 2025SP-BIO-111-PSNT1: Natu X Natural Selection in insects X + newconnect.mheducation.com/student/todo CA NATURAL SELECTION NATURAL SELECTION IN INSECTS (HARDY-WEINBERG LAW) INTRODUCTION LABORATORY SIMULATION A Lab Data Is this the correct allele frequency? Is this the correct genotype frequency? Is this the correct phenotype frequency? Total 1000 Phenotype Frequency Typica Carbonaria Allele Frequency 9 P 635 823 968 1118 1435 Color Initial Frequency Light 0.25 Dark 0.75 Frequency Gs 0.02 Allele Initial Allele Frequency Gs Allele Frequency d 0.50 0 D 0.50 0 Genotype Frequency Moths Genotype Color Moths Released Initial Frequency Frequency G5 Number of Moths Gs NC - Xarrow_forwardWhich of the following is not a sequence-specific DNA binding protein? 1. the catabolite-activated protein 2. the trp repressor protein 3. the flowering locus C protein 4. the flowering locus D protein 5. GAL4 6. all of the above are sequence-specific DNA binding proteinsarrow_forwardWhich of the following is not a DNA binding protein? 1. the lac repressor protein 2. the catabolite activated protein 3. the trp repressor protein 4. the flowering locus C protein 5. the flowering locus D protein 6. GAL4 7. all of the above are DNA binding proteinsarrow_forward
- What symbolic and cultural behaviors are evident in the archaeological record and associated with Neandertals and anatomically modern humans in Europe beginning around 35,000 yBP (during the Upper Paleolithic)?arrow_forwardDescribe three cranial and postcranial features of Neanderthals skeletons that are likely adaptation to the cold climates of Upper Pleistocene Europe and explain how they are adaptations to a cold climate.arrow_forwardBiology Questionarrow_forward
- ✓ Details Draw a protein that is embedded in a membrane (a transmembrane protein), label the lipid bilayer and the protein. Identify the areas of the lipid bilayer that are hydrophobic and hydrophilic. Draw a membrane with two transporters: a proton pump transporter that uses ATP to generate a proton gradient, and a second transporter that moves glucose by secondary active transport (cartoon-like is ok). It will be important to show protons moving in the correct direction, and that the transporter that is powered by secondary active transport is logically related to the proton pump.arrow_forwarddrawing chemical structure of ATP. please draw in and label whats asked. Thank you.arrow_forwardOutline the negative feedback loop that allows us to maintain a healthy water concentration in our blood. You may use diagram if you wisharrow_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




