AQA B1 chapter 1 Cell structure and transport Flashcards
what is resolution?
The ability to distinguish between two separate points in an image. A light microscope can resolve to point approx 200nm apart, but an electron microscope can resolve two points only 0.2nm apart.
what structures are in animal cell?
cell membrane, ribosomes, mitochondria, cytoplasm and a nucleus
what structures are in plant cell?
cell membrane, ribosomes, cellulose cell wall, mitochondria, cytoplasm, large permanent vacuole, chloroplasts and nucleus
functions of the cell membrane
controls what enters and leaves the cell
functions of the cytoplasm
jelly-like substance. Site of chemical reactions and contains enzymes
functions of the nucleus
contains the genetic material (DNA)
functions of ribosomes
site of protein synthesis
functions of mitochondria
site of respiration
functions of cellulose cell wall
strength and support to the plant. It is fully permeable.
functions of chloroplasts
site of photosynthesis. Contains chlorophyll (green pigment) which traps light energy.
functions of a large permanent vacuole
contains cell sap. Found in the cytoplasm.
how do you set up a microscope?
start by clipping the slide you’ve prepared onto the stage
select the lowest-powered objective lens (i.e. the one that produces the lowest magnification).
use the coarse adjustment knob to move the stage up to just below the objective lens.
look down the eyepiece use the coarse adjustment knob to move the stage downwards until the image is roughly in focus
adjust the focus with the fine adjustment knob, until you get a clear image of what’s on the slide
if you need to see the slide with greater magnification, swap to a higher-powered objective lens and refocus.
how to prepare a slide for a microscope
add a drop of water to middle of a clean slide
cut up an onion an separate it out into layers use tweezers to peel off some epidermal tissue from the bottom of one of the layers
using the tweezers, place the epidermal tissue into the water on the slide.
add a drop of iodine solution iodine solution is a stain stains are used to highlight objects in a cell by adding colour to them
when calculating magnification what formula should we use?
magnification = image size divided by actual size of specimen
for example an onion cell measures 5mm, it’s actual size is 0.05 micrometers. calculate its magnification
image size = 5 millimetres = 5000 micrometers
actual size of specimen = 0.5 micrometers
m = image size divided by actual size = 5000 divided by 5 = x1000
magnification = x1000
how are sperm cells adapted for their function
Streamlined head and long tail to aid swimming
Many mitochondria (where respiration happens) which supply the energy to allow the cell to move
The acrosome (top of the head) has digestive enzymes which break down the outer layers of membrane of the egg cell
how are nerve cells adapted for their function
specialised to transmit electrical signals quickly from one place in the body to another The axon is long enabling the impulses to be carried along long distances
Having lots of extensions from the cell body (called dendrites) means branched connections can form with other nerve cells
The nere endings have many mitochondria which supply the energy to make special ransmitter chemicals called neurotransmitters. These allow the impulse to be passed from one cell to another.