Biology Notes Paper 1
B1 - CELL STRUCTURE AND TRANSPORT
Includes The world of the microscope, animal and plant cells, eukaryotic and prokaryotic cells,
specialisation in animal cells, specialisation in plant cells, diffusion, osmosis, osmosis in plants,
active transport, exchanging materials
Microscopes
● Magnification is the enlargement of an image
● Resolution is the ability to tell 2 objects apart
● Light microscopes have colour lenses, cheap, can move but do not have good
resolution or magnifications
● Electron microscopes have better resolution, are 3D and have better magnification.
But they are very expensive, only black and white and are not portable
● Magnified Image size = actual size x magnification
● 1m = 100cm
● 1cm = 10mm
● 1mm = 1000 um (micrometre)
● 1um = 1000nm (nanometre)
○ Nucleus - controls all activities of the cell and contains the genetic material
○ Cytoplasm - A jelly-like substance where most of the chemical reactions take
place
○ Cell membrane - Controls what goes in and out of the cell
○ Mitochondria - structures in the cytoplasm where aerobic respiration takes
place, releasing energy for the cell
○ Ribosomes - where protein synthesis takes place making all the proteins
needed in the cell
Plants animal and Plant Cells
● Animal cells contain:
○ Plants have everything that animal cells have as well as a few more
○ Cell Wall - Rigid structure that strengthens the cell
○ Chloroplasts - Contain chlorophyll which absorbs light for photosynthesis
○ Vacuole - A space in the cytoplasm filled with cell sap keeping the cell rigid
Prokaryotes and Eukaryotes
● In eukaryotic cells, DNA is in a clear nucleus
● It also has membrane-bound organelles
● It has a cell membrane, cytoplasm, and nucleus
● All animals, plants, fungi and protists are eukaryotes
● Prokaryotes are much smaller
● In prokaryotic cells, the DNA is free in the cytoplasm ( no clear nucleus )
● They consist of cytoplasm, ribosomes and a cell membrane surrounded by a cell wall
● They contain plasmids which code for very specific features such as antibiotic
resistance
● Bacteria are single-celled organisms which is a prokaryotic cell
Specialist cells
● Specialised cells have particular jobs and special features that help them perform
these jobs.
, ● Red blood cells have no nucleus as they need to make room for the oxygen that they
need to carry around the body
● Nerve cells are specialised to carry electrical impulses around the body
● In plants, root hair cells are specialised to take in water
● Firstly they have a large surface area to allow water to move into the cell
● They have a large permanent vacuole which speeds up the movement of water by
osmosis
Diffusion
● Diffusion - the movement of particles from an area of high concentration to an area of
low concentration
● Diffusion does not require energy
● It doesn’t require a membrane
● Rates of diffusion = particles moving in - particles moving out.
● The rate of diffusion is affected by the concentration, temperature, and available
surface area.
Osmosis
● When water moves across a partially permeable membrane from a dilute solution to
a concentrated solution is called osmosis.
● Osmosis transfers only water molecules through a partially permeable membrane
● This membrane does not let all types of particles move through and only lets water
● It requires no energy
● If the concentration of solutes in the solution outside the cell is the same as the
internal concentration, the solution is isotonic to the cell
● If the concentration is higher than the internal concentration, the solution is
hypertonic to the cell. The cells will shrivel up and die due to the lack of water
● If the concentration is lower than the internal concentration, the solution is hypotonic
to the cell . The cells would swell and burst
● Osmosis is important to maintain turgor in plant cells
Active transport
● Particles move from a low concentration to a high concentration. This is against the
concentration gradient
● It needs energy to carry a molecule across the membrane and then return to its
original position. This energy is produced during the cell’s respiration..
● In humans active transport occurs in the small intestine so it can absorb glucose from
digested food.
Surface area: Volume
● Surface area: number of faces x (length x width)
● Volume is the amount of space inside something
● Volume: length x width x height
● A large (surface area:volume ratio) means diffusion occurs more efficiently
●
B2 - CELL DIVISION
Includes Cell division, growth and differentiation, stem cells, stem cell dilemmas
Cell division
● 46 Chromosomes are found in pairs in body cells in the nucleus
B1 - CELL STRUCTURE AND TRANSPORT
Includes The world of the microscope, animal and plant cells, eukaryotic and prokaryotic cells,
specialisation in animal cells, specialisation in plant cells, diffusion, osmosis, osmosis in plants,
active transport, exchanging materials
Microscopes
● Magnification is the enlargement of an image
● Resolution is the ability to tell 2 objects apart
● Light microscopes have colour lenses, cheap, can move but do not have good
resolution or magnifications
● Electron microscopes have better resolution, are 3D and have better magnification.
But they are very expensive, only black and white and are not portable
● Magnified Image size = actual size x magnification
● 1m = 100cm
● 1cm = 10mm
● 1mm = 1000 um (micrometre)
● 1um = 1000nm (nanometre)
○ Nucleus - controls all activities of the cell and contains the genetic material
○ Cytoplasm - A jelly-like substance where most of the chemical reactions take
place
○ Cell membrane - Controls what goes in and out of the cell
○ Mitochondria - structures in the cytoplasm where aerobic respiration takes
place, releasing energy for the cell
○ Ribosomes - where protein synthesis takes place making all the proteins
needed in the cell
Plants animal and Plant Cells
● Animal cells contain:
○ Plants have everything that animal cells have as well as a few more
○ Cell Wall - Rigid structure that strengthens the cell
○ Chloroplasts - Contain chlorophyll which absorbs light for photosynthesis
○ Vacuole - A space in the cytoplasm filled with cell sap keeping the cell rigid
Prokaryotes and Eukaryotes
● In eukaryotic cells, DNA is in a clear nucleus
● It also has membrane-bound organelles
● It has a cell membrane, cytoplasm, and nucleus
● All animals, plants, fungi and protists are eukaryotes
● Prokaryotes are much smaller
● In prokaryotic cells, the DNA is free in the cytoplasm ( no clear nucleus )
● They consist of cytoplasm, ribosomes and a cell membrane surrounded by a cell wall
● They contain plasmids which code for very specific features such as antibiotic
resistance
● Bacteria are single-celled organisms which is a prokaryotic cell
Specialist cells
● Specialised cells have particular jobs and special features that help them perform
these jobs.
, ● Red blood cells have no nucleus as they need to make room for the oxygen that they
need to carry around the body
● Nerve cells are specialised to carry electrical impulses around the body
● In plants, root hair cells are specialised to take in water
● Firstly they have a large surface area to allow water to move into the cell
● They have a large permanent vacuole which speeds up the movement of water by
osmosis
Diffusion
● Diffusion - the movement of particles from an area of high concentration to an area of
low concentration
● Diffusion does not require energy
● It doesn’t require a membrane
● Rates of diffusion = particles moving in - particles moving out.
● The rate of diffusion is affected by the concentration, temperature, and available
surface area.
Osmosis
● When water moves across a partially permeable membrane from a dilute solution to
a concentrated solution is called osmosis.
● Osmosis transfers only water molecules through a partially permeable membrane
● This membrane does not let all types of particles move through and only lets water
● It requires no energy
● If the concentration of solutes in the solution outside the cell is the same as the
internal concentration, the solution is isotonic to the cell
● If the concentration is higher than the internal concentration, the solution is
hypertonic to the cell. The cells will shrivel up and die due to the lack of water
● If the concentration is lower than the internal concentration, the solution is hypotonic
to the cell . The cells would swell and burst
● Osmosis is important to maintain turgor in plant cells
Active transport
● Particles move from a low concentration to a high concentration. This is against the
concentration gradient
● It needs energy to carry a molecule across the membrane and then return to its
original position. This energy is produced during the cell’s respiration..
● In humans active transport occurs in the small intestine so it can absorb glucose from
digested food.
Surface area: Volume
● Surface area: number of faces x (length x width)
● Volume is the amount of space inside something
● Volume: length x width x height
● A large (surface area:volume ratio) means diffusion occurs more efficiently
●
B2 - CELL DIVISION
Includes Cell division, growth and differentiation, stem cells, stem cell dilemmas
Cell division
● 46 Chromosomes are found in pairs in body cells in the nucleus
