Biological Science
Biological Science
5th Edition
ISBN: 9780321743671
Author: Scott Freeman
Publisher: PEARSON
bartleby

Concept explainers

Question
Book Icon
Chapter 43, Problem 2TYK
Summary Introduction

Introduction:

The epithelial cells in the gills of freshwater have a higher concentration of solutes than the surrounding water where fishes live, that is they are hyper-osmotic to the surrounding water.

Expert Solution & Answer
Check Mark

Answer to Problem 2TYK

Correct answer:

In freshwater fishes, water enters epithelial cells in their gills via osmosis. Whereas, the electrolytes leave the same cells via diffusion.

Explanation of Solution

Explanation/justification for the correct answer:

Option (c) is given that water enters epithelial cells in the gills of freshwater fishes via osmosis and electrolytes leaves the same cells via diffusion. The freshwater fishes maintain the electrolyte balance (osmoregulation) with their external environment. This osmoregulation is maintained by the entry of freshwater into the epithelial cells of the gills through the process of osmosis.

In this, the transfer of solvent (water) from the region of less solute concentration (water body, for example, a freshwater river) to the region of higher solute concentration (epithelial cells in the gills) takes place. In order to maintain homeostasis, the excess water intake is excreted in the urine.

The excess solute (electrolytes) present in the epithelial cells leaves the cells via the process of diffusion. The level of lost electrolytes is maintained by food intake or through their active transport from the freshwater present outside. Hence, option (c) is correct.

Explanation for incorrect answer:

Option (a) is given that water surrounding the fish is iso-osmotic. As a result, no special organ is required to maintain water and electrolyte balance. So, it is a wrong answer.

Option (b) is given that freshwater fishes lose water to their environment primarily through the gills, and replace this water by drinking. The epithelial cells of freshwater fishes have less amount of water and they possess a higher solute concentration; therefore, they take in water by osmosis instead of losing it via gills. So, it is a wrong answer.

Option (d) is given that freshwater fishes have specialized epithelia that actively pump Na+ (sodium ions) and Cl- (chloride ions) from the blood into their environment. The specialized epithelia in the gills help to actively pump in the electrolytes (sodium ions and chloride ions) from the outside environment to maintain the levels of electrolyte, which were lost due to diffusion. So, it is a wrong answer.

Hence, options (a), (b), and (d) are incorrect.

Conclusion

Therefore, it can be concluded that the concentration of solute in the epithelial cells of the gills of freshwater fishes is higher than in the water outside. The osmoregulation is maintained by osmosis (water enters the epithelial cells) and diffusion (water leaves the cells). Thus, the water enters epithelial cells in the gills of freshwater fishes via osmosis and the electrolytes leave those cells through diffusion.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
You aim to test the hypothesis that the Tbx4 and Tbx5 genes inhibit each other's expression during limb development. With access to chicken embryos and viruses capable of overexpressing Tbx4 and Tbx5, describe an experiment to investigate whether these genes suppress each other's expression in the limb buds. What results would you expect if they do repress each other? What results would you expect if they do not repress each other?
You decide to delete Fgf4 and Fgf8 specifically in the limb bud. Explain why you would not knock out these genes in the entire embryo instead.
You implant an FGF10-coated bead into the anterior flank of a chicken embryo, directly below the level of the wing bud. What is the phenotype of the resulting ectopic limb?  Briefly describe the expected expression domains of 1) Shh, 2) Tbx4, and 3) Tbx5 in the resulting ectopic limb bud.
Knowledge Booster
Background pattern image
Biology
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
BIOLOGY:CONCEPTS+APPL.(LOOSELEAF)
Biology
ISBN:9781305967359
Author:STARR
Publisher:CENGAGE L
Text book image
Biology Today and Tomorrow without Physiology (Mi...
Biology
ISBN:9781305117396
Author:Cecie Starr, Christine Evers, Lisa Starr
Publisher:Cengage Learning
Text book image
Aquaculture Science
Biology
ISBN:9781133558347
Author:Parker
Publisher:Cengage
Text book image
Biology (MindTap Course List)
Biology
ISBN:9781337392938
Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg
Publisher:Cengage Learning
Text book image
Anatomy & Physiology
Biology
ISBN:9781938168130
Author:Kelly A. Young, James A. Wise, Peter DeSaix, Dean H. Kruse, Brandon Poe, Eddie Johnson, Jody E. Johnson, Oksana Korol, J. Gordon Betts, Mark Womble
Publisher:OpenStax College
Text book image
Human Physiology: From Cells to Systems (MindTap ...
Biology
ISBN:9781285866932
Author:Lauralee Sherwood
Publisher:Cengage Learning