Concept explainers
Test your Understanding
Know and Comprehend
A radially symmetrical animal such as Hydra is likely to have (a) a forebrain (b) a nerve net (c) cerebral ganglia (d) a ventral nerve cord (e) cerebral ganglia and a nerve net
Introduction: Hydra is a freshwater organism of the phylum Cnidaria. They have very high regenerative ability. They are radially symmetrical invertebrates and have tentacles to capture their food.
Answer to Problem 1TYU
Correct answer: Radially symmetrical organisms such as Hydra have simple nervous systems like the nerve net. Hence, the correct answer is option (b).
Explanation of Solution
Reason for the correct answer:
Radial symmetry is generally present in simpler organisms such as Hydra. Organisms belonging to simpler classes in the animal kingdom have less complexed nervous systems. They usually have interconnected networks of neurons, and no central control system is present in such simpler neural systems. Such connection of neurons forms the nerve net.
Option (b) is given as “a nerve net”.
Radially symmetrical organisms such as Hydra have simpler body organization and simpler nervous systems such as the nerve nets. Hence, the correct answer is option (b).
Reasons for incorrect answers:
Option (a) is given as “a forebrain”.
A forebrain is a part of a complex nervous system that is found in higher organisms with a complex body organization. The forebrain is not found in simpler organisms such as Hydra. Hence, option (a) is incorrect.
Option (c) is given as “cerebral ganglia”.
Radially symmetrical organisms have simple nervous systems that do not have any control center. Cerebral ganglia act as a control center in the nervous systems. Hence, option (c) is incorrect.
Option (d) is given as “a ventral nerve cord”.
Ventral and dorsal sides can be defined only in organisms with bilateral symmetry. In organisms with simple body organization, there is no nerve cord present. Thus, radially symmetrical organisms cannot have a ventral nerve cord. Hence, option (d) is incorrect.
Option (e) is given as “cerebral ganglia and a nerve net”.
Simpler organisms do not have cerebral ganglia in their nervous systems. Hence, option (e) is incorrect.
Hence, options (a), (c), (d), and (e) are incorrect.
Organisms with radial symmetry in their body organization, such as Hydra, have a nervous system consisting only of nerve nets.
Want to see more full solutions like this?
Chapter 42 Solutions
Biology (MindTap Course List)
- Other than oil and alcohol, are there other liquids you could compare to water (that are liquid at room temperature)? How is water unique compared to these other liquids? What follow-up experiment would you like to do, and how would you relate it to your life?arrow_forwardSelection of Traits What adaptations do scavengers have for locating and feeding on prey? What adaptations do predators have for capturing and consuming prey?arrow_forwardCompetition Between Species What natural processes limit populations from growing too large? What are some resources organisms can compete over in their natural habitat?arrow_forward
- Species Interactions Explain how predators, prey and scavengers interact. Explain whether predators and scavengers are necessary or beneficial for an ecosystem.arrow_forwardmagine that you are conducting research on fruit type and seed dispersal. You submitted a paper to a peer-reviewed journal that addresses the factors that impact fruit type and seed dispersal mechanisms in plants of Central America. The editor of the journal communicates that your paper may be published if you make ‘minor revisions’ to the document. Describe two characteristics that you would expect in seeds that are dispersed by the wind. Contrast this with what you would expect for seeds that are gathered, buried or eaten by animals, and explain why they are different. (Editor’s note: Providing this information in your discussion will help readers to consider the significance of the research).arrow_forwardWhat is the difference between Uniporters, Symporters and Antiporters? Which of these are examples of active transport?arrow_forward
- What are Amyloid Fibrils? What biological functions are these known to perform?arrow_forwardHow do histamine and prostaglandins help in the mobilization of leukocytes to an injury site? What are chemotactic factors? How do they affect inflammation process?arrow_forwardCompare and contrast neutrophils and macrophages. Describe two ways they are different and two ways they are similar.arrow_forward
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage LearningBiology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning
- Biology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxBiology: The Unity and Diversity of Life (MindTap...BiologyISBN:9781305073951Author:Cecie Starr, Ralph Taggart, Christine Evers, Lisa StarrPublisher:Cengage Learning