Fish and insects don't have lungs like humans and other mammals do. Instead, they have clever alternative gas exchange systems in order to deliver oxygen to their cells. Let's look at each organism individually. Gas Exchange in Fish I'm sure it's fairly obvious that fish don't breath air because they live underwater. Instead, they must... Continue Reading →
We've now looked at three ways in which substances can be transported across cell membranes: diffusion, osmosis, and active transport. Today's topic is example of where diffusion takes place in the human body, all with the purpose of taking in oxygen for respiration and removing carbon dioxide. There's quite a lot of information today so... Continue Reading →
So far we have looked at the passive movement of substances across cell membranes by diffusion and osmosis. Sometimes substances need to move against a concentration gradient, which is when active transport comes into action. Active transport Active transport uses energy from ATP to transport substances from an area of low concentration to an area... Continue Reading →
Osmosis is all about the movement of water. Specifically, it is the diffusion of free water molecules from an area of high water potential to an area of low water potential across a partially permeable membrane. As we saw in diffusion, the water molecules move both ways, but the overall net movement is down the... Continue Reading →
Diffusion is one of those topics that pops up at all levels of biology, and each time gets a little more complicated. But it is still the basic process of substances evenly distributing themselves. It is just a little more complex when it happens across a cell membrane. Simple diffusion Firstly, lets recap the basics... Continue Reading →
Today we are starting a new series looking at how substances are exchanged across cell membranes and transported around organisms. These processes are really important for getting essential resources such as oxygen and glucose to all the cells in an organism. We will start by taking a closer look at the structure of the cell... Continue Reading →
