Bio 1500 Exam One

First Homo sapiens

200,000 years ago

First dinosaurs

240 mya

Oldest fossils

3.5 billion years ago

One area in a cell has a higher density of a certain type of molecule compared to a neighboring area. This situation describes:

a concentration gradient

The highest rates of diffusion are associated with

high temperatures large diffusion surface area steep concentration gradient

How does facilitated transport differ from diffusion?

in facilitated transport, the substance passes through a pore, or tunnel, inside other molecules in the membrane

What does it mean if a channel is gated?

sometimes the channel allows molecules to pass through, and sometimes it doesn't

What is diffusion?

the spontaneous movement of molecules away from areas of highest density

What is the difference (or relationship) between the terms diffusion and osmosis?

they both function in the same way, but osmosis refers specifically to the diffusion of water molecules

After molecules have moved around until there is no longer a concentration gradient, how do the molecules behave?

they continue moving, but their density remains relatively even throughout the space

Bacterial Photosynthesis

2,700,000,000 years ago

Earth formed

4.6 billion years ago

First Insects

480 mya

Cretaceous Extinction

66 million years ago;

What benefit do cells obtain by using facilitated transport instead of simple (=unfacilitated) diffusion to move material across a membrane?

Some molecules have positive and negative regions (i.e. polarity) that prevent them from moving easily through the membrane; facilitated transport overcomes this problem

Which three of the following are types of transport proteins?

channel proteins aquaporins carrier proteins