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.
how are muscle cells adapted to their function
special proteins (myosin and actin) slide over each other, causing the muscle to contract Lots of mitochondria to promide energy from respiration for conraction
They can store a chemical called glycogen ha is sed in respiration by mitochondria
how are root hair cells adapted to their function
Have a large surface area due to root hairs meaning more water can move in
The large permanent vacuole affects the speed of movement of water from the soil to the cell
Mitochondria to provide energy from respiration for the active transport of mineral ions into the
root hair cell.
how are xylem cells adapted to their function
upon formation, a chemical called lignin is depostied which causes the cells to die
They become hollow and are joined end-to-end to form a continuous tube so water and mineral ions can move through
Lignin is deposited in spirals which helps the cells withstand the pressure from the movement of water
how are phloem cells adapted to their function
Cell walls of each cell form sructures called sieve plates when they break down, allowing the movement of substances from cell to cell
Despite losing many sub-cellular structures, the energy these cells need to be alive is supplied by the mitochondria of the companion cells.
what is a prokaryotic cell
prokaryotes are simple unicellular organisms e.g. a bacterium a cell without a nucleus
what is a eukaryotic cell
Eukaryotic organisms are complex multicellular organisms e.g. a human, an oak tree.
compare prokaryotic and eukaryotic cells
the size of prokaryotic cells are extremely small (less than 2 micrometers in diameter) whereas eukaryotic cells are much larger cells (10 micrometers-100 micrometers)
in a prokaryotic cell there is no nucleus on the other hand in a eukaryotic cell there is a nucleus present
in a prokaryotic cell DNA is circular (only one loop of DNA) whereas in a eukaryotic DNA is linear (many chromosomes)
prokaryotic cells have few organelles but eukaryotic cells have many organelles
an example of a prokaryotic cell is an ecoli bacterium and an example of a eukaryotic cell is a human skin cell.
what is diffusion
diffusion is the net movement of particles from an area of high concentration to an area of low concentration diffusion is a passive process (no energy)
how does potassium permanganate diffuse in warm water compared to cold water
Potassium permanganate has diffused quicker in the warmer beaker because the particles move quicker in hotter temperatures than they do in cold temperatures.
what can affect diffusion
Temperature can affect the rate of diffusion if the temperature is hotter diffusion will happen at a quicker rate.
If the diffusion distance is longer diffusion will take longer to spread out. Whereas if the diffusion is shorter it will be quicker.
States of matter will affect how fast the particles move throughout the room. Gasses diffuse more quickly than liquids, solids do not diffuse at all.
what is osmosis
the movement of water molecules from an area of high concentration to an area of low concentration across a partially permeable membrane.
explain what would happen if bag made from semipermeable membrane is tied to a glass tube and filled with a concentrated sugar solution.
This bag is placed in a less concentrated sugar solution.
The water molecules will move from a dilute solution (the water outside the bag) through the semipermeable membrane and moves into the concentrated solution (in the visking tube). The water then moves up the capillary tube because there is more than before. This process is called osmosis.
describe and explain the process that takes place when a 30% sugar solution is then placed with an egg inside.
With the medium concentration water the egg has grown bigger there was 30% sugar. This is because the water has moved from a place of high concentration to a place a low concentration. The water has moved from the container into the semipermeable membrane. This is called osmosis. The water molecules will move from a dilute solution (the water outside the egg) through the semipermeable membrane and moves into the concentrated solution where the egg will have a lot of water inside it.
what does it mean by lysic
lysic means burst
what does it mean by crenation
crenation means shrivel
describe what happens when cells are placed in distilled water compared to when they are placed in concentrated salt solution
when cells are placed in distilled water they swell and burst whereas when cells are placed in concentrated salt solution they shrink and shrivel
describe and explain what happens when cells are placed in distilled water
the water moves from a dilute solution (inside the cell) to concentrate solution (outside the cell). The water moves through the partially-permeable into the cell and the cells swell and eventually burst (lysis).
describe and explain what happens when cells are placed in a concentrated solution
the water moves from the concentrated solution (in the cell) through the partially-permeable-membrane to the dilute solution (outside the cell). The cells shrivel and shrink (crenation).
how to investigate the effect of sugar or salt solutions on a plant tissue
Cut the potato into small pieces each different masses with a sharp knife.
Prepare 6 different solutions each with a different amount of sugar inside.
The 1st one will just be distilled water, 5% sugar, 10% sugar, 15% sugar, 20% sugar, 25% sugar and 30% sugar. Make sure to cut all the skin off.
Cut them into 3cm for each potato piece.
Weigh the potato pieces individually before they go in the water.
Leave them in the water for at least 40 mins (the longer the better).
After it has been in the water for at least 40 minutes take it out and measure it in grams (g) and record them individually.
Record your results in the table on the next page
conclusion describe and explain for investigating the effect of sugar or salt solutions on plant tissue.
With the 50% concentration water the potato has gone down in mass. This is because the water has moved from a place of low concentration (the potato) to a place of high concentration (the water). The water has moved from the potato through the semipermeable membrane. This is called osmosis. The water molecules have moved from a concentrated solution (the potato) through the semipermeable membrane and moves into the dilute solution where the boiling tube will have more water inside it than before. With the 0% the mass increased by 4%. This is because the water has moved from a dilute solution (the water) through the semi-permeable membrane into a now concentrated solution (the potato). With the 100% sugar the mass of the potato has decreased by 14.2%. This is because the water has moved out of the potato (the dilute solution) through a semi-permeable membrane into the beaker with the water (the concentrated solution) by a process of osmosis. At 0.3 mol/dm cubed there is no net movement in and out of the cell tissue, it was at equilibrium with the water.
what is active transport
the movement of substances from an area of low concentration to an area of higher concentration. Against a concentration gradient, requires ATP energy and a carrier protein in the cell membrane.
give two examples of active transport
E.g. glucose is sometimes actively transported from your small intestine into the bloodstream.
E.g. mineral ions in water are actively transported from the soil into the root hair cells.
how does a cell release energy
by respiration
where in a cells does this happen
mitochondria
what does more area mean in terms of active transport
The more area there is the more oxygen the more respiration which means energy is released which helps active transport happen more efficiently.
how to work out surface area to volume ratio
find the surface area by adding up all of the faces’s areas and find the volume by multiplying the width by the length by the height
then simplify e.g. 24:8 would simplify to 3:1
