Key visualizations: Biology

In high school biology, students build on their knowledge of cells by examining cell processes that maintain homeostasis. Students develop an understanding of how the cell membrane controls substances that enter and leave the cell. They examine passive transport systems as cells exchange materials with their environment. This provides a foundation for continued exploration of organization and interactions of systems in organisms and the role of internal feedback mechanisms in the maintenance of homeostasis.

Connections to the TEKS []

This animation addresses the following Biology TEKS:

(4)  Science concepts. The student knows that cells are the basic structures of all living things with specialized parts that perform specific functions and that viruses are different from cells. The student is expected to:

(B)  investigate and explain cellular processes, including homeostasis, energy conversions, transport of molecules, and synthesis of new molecules.
Students access this content through these process standards.

(3)  Scientific processes. The student uses critical thinking, scientific reasoning, and problem solving to make informed decisions within and outside the classroom. The student is expected to:

(E) evaluate models according to their limitations in representing biological objects or events.


About this animation []

In this animation, students examine how cells maintain relatively constant internal conditions to adjust to changing conditions. They look at the process of osmosis to discover that water molecules pass through the cell membrane in response to the amount of solutes present in passive transport. A strong foundation in these ideas will support students in future learning about how systems function and interact in organisms.


The cells of a marine fish have a lower concentration of salts than the surrounding water. Will osmosis move water into or out of the fish’s cells? What strategies the fish use to maintain a overall balance of water and salt throughout its body? Select one strategy from each box, then click the Check button.
Correct! Osmosis causes water to leave the fish's body. The fish responds by drinking water to replace what is lost. The fish also uses special mechanisms to excrete salt from its body.
Try again. Your fish has too much salt.
Try again. Remember, because of osmosis, water tends to flow out of the fish’s body. Your fish is losing too much water and has too much salt.
Try again. Remember, because of osmosis, water tends to flow out of the fish’s body. Your fish is losing too much water.
The cells of a freshwater fish have a higher concentration of salts than the surrounding water. Will osmosis move water molecules into or out of the fish’s cells? What strategies can the fish use to maintain an overall balance of water and salt throughout its body? Select one strategy from each box, then click the Check button.
Try again. Remember, because of osmosis, water tends to flow into the fish’s body. Your fish has too much water and not enough salt.
Try again. Remember, because of osmosis, water tends to flow into the fish’s body. Your fish has too much water inside it.
Correct! Osmosis moves water into the fish's body. The fish responds by excreting dilute urine. It also replaces any lost salt by taking in salt with its food.
Try again. Your fish is losing too much salt.
Click on a fish to explore how it maintains its internal conditions. Make sure to explore both the freshwater fishes and marine fishes. Press Reset to set up the other fish.