AP Biology class blog for discussing current research in Biology

Tag: organisms

Heat Waves in U.S Rivers Rise

Heat Waves in U.S Rivers have been rising. Why have they been rising and what are the effects of this? According to research in the article, heat waves in rivers have been occurring more recently and more frequently due to the warm weather. Scientists studied different Rivers in the U.S and found that rivers that are upstream from reservoirs cause extreme heat while rivers downstream from reservoirs don’t cause heat because the dam is able to cool off the water. They also said that where these rivers are located there are warmer winters then usual. Another key thing that they also found is that less precipitation will also have an effect because there is less water in the river therefore making it warmer. Another bad thing about this is that it is affecting the organisms that live in the rivers. In the research, they said that animals like salmon and trout like cold water and need it in order to obtain oxygen and regulate their body temperature. Scientists say that dams are looking promising in order to stop this rise in heat.


According to another article, a similarity between the two articles is the worry about wildlife and how this heat will affect them going forward.


According to a third article, another worry that relates to all of this is that a rise in heat will cause more evaporation meaning there will be less water. If there is also less precipitation that means that there will be little water in the river and everything will get worse.


This ties into what we have learned so far in class because of the way organisms need certain things in order to survive. During our pill bug lab we were able to understand where pills bug lived and how we would find them in order to bring to class. They live under rocks usually and like damp soil. Without this they can die quickly. In the research from the articles we see how the organisms need certain things in order for them to live too. The fish need cold water so they can retrieve oxygen and regulate their internal temperature. So we see how organisms need certain necessities in order to live.

Riviere river




Bacteria may be more complex than we think

Photo by Wikimedia Commons

A common public misconception is that bacteria live alone and act as solitary organisms. This misconception, however, is far from reality.

Bacteria always live in very dense communities. Most bacteria prefer to live in a biofilm, a name for a group of organisms that stick together on a surface in an aqueous environment. The cells that stick together form an extracellular matrix which provides structural and biochemical support to the surrounding cells. In these biofilms, bacteria increase efficiency by dividing labor. The exterior cells in the biofilm defend the group from threats while the interior cells produce food for the rest.

While it has long been known that bacteria can communicate through the group with chemical signals, also known as quorum sensing, new studies show that bacteria can also communicate with one another electrically. Ned Wingreen, a biophysicist at Princeton describes the significance of the discovery; “I think these are arguably the most important developments in microbiology in the last couple years, We’re learning about an entirely new mode of communication.”

An entirely new mode of communication it is! Heres how it works:

Ion channels in a bacteria cell’s outer membrane allow electrically charged molecules to pass in and out, just like a neuron or nerve cell. Neurons pump out Sodium ions and let in Potassium ions until the threshold is reached and depolarization occurs. This is known as an action potential. Gurol Suel, a biophysicist at UCSD emphasizes that while the bacteria’s electrical impulse is similar to a neuron’s, it is much slower, a few millimeters per hour compared to a neuron’s 100 meters per second.

Photo by Chris 73 Wikimedia Commons

So what does this research mean?

Scientists agree that this revelation could open new doors to discovery. Suel says that electrical signaling has been shown to be stronger than traditional chemical signaling. In his research, Suel found that potassium signals could travel at constant strength for 1000 times the width of a bacteria cell, much longer and stronger than any chemical signal. Electrical signaling could also mean more communication between different bacteria. Traditional chemical signaling relies on receptors to receive messages, while bacteria, plant cells, and animal neurons all use potassium to send and receive signals. If these findings are correct, there’s potential in the future for the development of new antibiotics.

Learning about electrical signaling in bacteria has complicated our understanding of these previously thought to be simple organisms. El Naggar, another biophysicist at USC says, “Now we’re thinking of [bacteria] as masters of manipulating electrons and ions in their environment. It’s a very, very far cry from the way we thought of them as very simplistic organisms.”



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