Biology paper 1 AQA
Differences between light microscope and electron microscope✔✔✔Light: are cheap to make and they
allow you to see the outline of cells
Electron: Very expensive, however you can visualise finer details (including sub-cellular structures) due
to higher resolution and greater resolving power
Equation for magnification✔✔✔Magnification = image size / real size
Differences between Eukaryotic and prokaryotic cells✔✔✔Eukaryotes have a nucleus in which their
DNA is found
(Plant and Animal cells)
Prokaryotes don't have a nucleus and their DNA is in loops call plasmids (Bacteria)
what does a cell membrane do and what is it✔✔✔semi-permeable, controls what enters and leaves
what does a cell wall do and what is it✔✔✔made of cellulose, providing rigid structure
what is cytoplasm and what happens in it✔✔✔liquid that makes up the cell, where most chemical
reactions take place
What does the mitochondria do?✔✔✔where respiration takes place, releasing energy for the cell to
function
what does chloroplasts do✔✔✔contain green pigment chlorophyll, where photosynthesis takes place
what does ribosomes do✔✔✔synthesises proteins
What does the vacuole do?✔✔✔where cell sap and minerals are stored
difference between diploid and haploid✔✔✔diploid: 23 pairs of chromosomes, 46 (human cells)
haploid: just 23 chromosomes, gametes (sperm/eggs)
what is mitosis✔✔✔division of cells for growth and repair
process of mitosis✔✔✔
, 1. nucleus dissolves, genetic material is duplicated
2. two sets of chromosomes more to different sides
3. mitochondria and other organelles are duplicated
4. the cell divides producing two genetically identical diploid cells (new nuclei are formed in each)
What can stem cells do and where are they found✔✔✔can specialise to perform specific functions.
found in human and animal embryos and plant meristems
what can stem cells in bone marrow be specialised into✔✔✔only specialise into blood cells
advantages of stem cells✔✔✔treat a wide range of diseases
disadvantages of stem cells✔✔✔rejection by the body's immune system
cells can mutate e.g can turn into cancer cells
what can embryonic stem cells do✔✔✔can develop into any type of body cell
ethical issues for embryonic stem cells✔✔✔involves the embryo being destroyed
what's diffusion✔✔✔- movement of particles from an area of high to low concentration
- down a concentration gradient
- passive: requires no energy
what's osmosis✔✔✔- diffusion of water across a semi-permeable membrane
- balances the concentrations of solution in and outside a cell
what increases the rate of diffusion and osmosis✔✔✔temperature, surface area, difference in
concentrations
osmosis practical: potatoes✔✔✔- weigh and place identical cylinders from the same potato in sugar
solutions of varying concentrations
- after a set time, remove excess water and reweigh
what's active transport✔✔✔- movement of particles through a membrane
Differences between light microscope and electron microscope✔✔✔Light: are cheap to make and they
allow you to see the outline of cells
Electron: Very expensive, however you can visualise finer details (including sub-cellular structures) due
to higher resolution and greater resolving power
Equation for magnification✔✔✔Magnification = image size / real size
Differences between Eukaryotic and prokaryotic cells✔✔✔Eukaryotes have a nucleus in which their
DNA is found
(Plant and Animal cells)
Prokaryotes don't have a nucleus and their DNA is in loops call plasmids (Bacteria)
what does a cell membrane do and what is it✔✔✔semi-permeable, controls what enters and leaves
what does a cell wall do and what is it✔✔✔made of cellulose, providing rigid structure
what is cytoplasm and what happens in it✔✔✔liquid that makes up the cell, where most chemical
reactions take place
What does the mitochondria do?✔✔✔where respiration takes place, releasing energy for the cell to
function
what does chloroplasts do✔✔✔contain green pigment chlorophyll, where photosynthesis takes place
what does ribosomes do✔✔✔synthesises proteins
What does the vacuole do?✔✔✔where cell sap and minerals are stored
difference between diploid and haploid✔✔✔diploid: 23 pairs of chromosomes, 46 (human cells)
haploid: just 23 chromosomes, gametes (sperm/eggs)
what is mitosis✔✔✔division of cells for growth and repair
process of mitosis✔✔✔
, 1. nucleus dissolves, genetic material is duplicated
2. two sets of chromosomes more to different sides
3. mitochondria and other organelles are duplicated
4. the cell divides producing two genetically identical diploid cells (new nuclei are formed in each)
What can stem cells do and where are they found✔✔✔can specialise to perform specific functions.
found in human and animal embryos and plant meristems
what can stem cells in bone marrow be specialised into✔✔✔only specialise into blood cells
advantages of stem cells✔✔✔treat a wide range of diseases
disadvantages of stem cells✔✔✔rejection by the body's immune system
cells can mutate e.g can turn into cancer cells
what can embryonic stem cells do✔✔✔can develop into any type of body cell
ethical issues for embryonic stem cells✔✔✔involves the embryo being destroyed
what's diffusion✔✔✔- movement of particles from an area of high to low concentration
- down a concentration gradient
- passive: requires no energy
what's osmosis✔✔✔- diffusion of water across a semi-permeable membrane
- balances the concentrations of solution in and outside a cell
what increases the rate of diffusion and osmosis✔✔✔temperature, surface area, difference in
concentrations
osmosis practical: potatoes✔✔✔- weigh and place identical cylinders from the same potato in sugar
solutions of varying concentrations
- after a set time, remove excess water and reweigh
what's active transport✔✔✔- movement of particles through a membrane
