B1 Flashcards
(It’s in the name)
How do electron microscopes form an image?
Using a beam of electrons
By how much do light and electron microscopes magnify an image?
light- up to 2000x
electron- up to 2000000x
What substance does the permanent vacuole contain?
Cell sap
What is the role of the cell membrane?
It controls the movement of substances in and out of the cell
What are plasmids in prokaryotic cells?
Circular rings of genetic material
How are nerve cells specialised to perform a specific function?
They have:
-Multiple dendrites to form connections to other nerve cells
-An axon which carries the impulse
-Synapses which pass impulses via transmitter chemicals
-Many mitochondria in synapses to transfer energy needed to make transmitter chemicals
Why do muscle cells need a lot of mitochondria?
To transfer energy needed for movement
Name two factors that affect the rate at which diffusion occurs:
-Steepness of the concentration gradient
-Temperature
-Surface area
What term is used to refer to two solutions with identical concentrations?
Isotonic
Which two words refer to (1) a solution that is more concentrated and (2) a solution that is less concentrated?
1) hypertonic
2) hypotonic
What happens to an animal cell if it is placed in a hypotonic solution?
It will swell as water enters the cell via osmosis.
A bag made of a partially permeable membrane containing a concentrated sugar solution is placed into a beaker of water. What do we expect will happen to the bag?
It will start to swell, as water enters through osmosis.
When does turgor pressure occur in a plant cell?
When no more water can enter a cell due to the internal pressure (+it causes the cell to become rigid/turgid)
What happens when plant cells are placed in a hypertonic solution?
The plant cells lose water and become flaccid in a process known as plasmolysis
How do root hair cells absorb mineral ions?
Active transport
