describe the Function of the Cell wall
Made of cellulose and gives rigidity. It supports and strengthens the cells
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Describe Cell membrane
Controls which substances enter and exit the cell
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Location of chemical reactions
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Location where aerobic respiration occurs
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Where photosynthesis occurs and where sugar is made, contains green chlorophyll for photosynthesis
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Large and permanent, contains cell sap, stores water
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Produce proteins that carry out important functions in the cells
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Circular DNA molecules, controls the activities and can aid antibiotic resistance.
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what do plant cells have that animal cells do have?
a rigid cell wall made of cellulose, a large permanent vacuole and chloroplasts
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what types of cell are prokaryotes?
Bacteria, because they are single-celled and small
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are algae plants
no they are protists
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name two differences in the structure prokaryotic and Eukaryoctic cells
prokaryotes may have flagella and ribosomes whereas eukaryotes do not
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what is a flagella
flagellum are long protein strands
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why are some bacteria dangerous
they can be pathogenic and they can also destroy food
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how do you show orders of magnitude?
you show it using powers of 10, if somethings is 10 times bigger than something it is 1 order of magnitude larger.
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why is cell differentiation important?
this allows cells to change and become specialized for its job
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when do cells differenciate
animal cells differenciate at an early stage but many plant cells keep this ability
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why do mature animal cells differenciate
for repairing and replacing skin and blood cells
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what is a cell called once it has differenciated
it is called specialized and this means that it has different sub-cellular structures in order to carry out a specific job
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what are the three main animal cells that specialise
sperm cells; for reproduction, nerve cells; rapid signalling and muscle cells; for contraction
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what are the three main plant cells that specialise
xylem; water transportation, phloem; sugars transportation and root hair cell for absorption of water and minerals.
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how are nerve cells specialised?
the function is to carry electrical signals, axons to carry nerve impulses and synapses with many mitochondria to provide energy needed to make transmitter signals.
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how are muscle cells specialised?
they can store gylcogen and contain many mitochondria for the chemical reations to occur
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how are sperm cells specialised?
a long tail helps for movement, the middle section is full of mitochondria for energy and a large nucleus for genetic information to be passed on
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how are root hair cells specialised?
large surface area for the absorption of water, a large permanent vacuole that speeds up osmosis
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How are xylem cells specialised?
spirals of lignin help the cell to be rigid and withstand pressure, cells die and form hollow tubes which allow water and mineral ions to be taken up
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How are phloem cells specialized?
the cell walls break down to form sieve plates that carry nutrients up and down the plant. they are also supported by companion cells that transfer energy by their mitochondria
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what are the advantages of using a light microscope
light microscopes are cheap, can be used anywhere and can magnify live specimens
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what are the disadvantages of using a light microscope?
they have a low resolution
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Advantages of using an electron microscope
they let us see smaller things in more detail such as ribosomes and plasmids
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negatives of electron microscopes?
they have to be kept in special conditions,, they are large, expensive and the specimen has to be dead.
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how to calculate magnification
I AM triangle. image size =magnification x size of object
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what is resolution?
the ability to distinguish between two points
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what is diffusion?
diffusion is the spreading out of partilces from an area of high concentration to a lower concentration, down a concentration gradient.
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what factors affect the rate of diffusion?
temperature, the bigger the concentration gradient and the surface area
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how do dissolved substances move in and out of cells?
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What are partially permeable membranes
membranes that only allow substances of a certain size to diffuse through
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what is osmosis?
osmosis is the net movement of water molecules across a partially permeable membrane from a region of high concentration to low concentration down a concentration gradient
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what is a dilute solution?
a solution that contains a high concentration of solvent and a low concentration of solute
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What is a concentrated solution?
a solution that contains a low concentration of solvent and a high concentration of solute
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what is an isotonic solution?
When the concentration of solutes in the cells is the same as the surroundings
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what is a hypertonic solution?
when the concentration of solvent in a cell is lower than the outside this causes water to diffuse out of the cell by osmosis
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What is a hypotonic solution?
When the solvent concentration inside is higher than the outside, this causes water to diffuse in by osmosis
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what happens to hypotonic animal cells
Because there is no cell wall the cell will burst
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what happens to hypertonic animal cells?
the water from the cell will go out to bring it to equilibrium and the cells will die
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what happens to hypotonic plant cells
water will rush into the cell but due to the cell wall the cell with become tugid
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What happens to hypertonic plant cells
water will diffuse out by osmosis causing the cell to become plasmolysed
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what is surface area to volume ratio
in small objects the sa:v ratio is large and this means that diffusion distances are short.
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what happpens when organisms get bigger in relation the surface area to volume ratio
the surface area to volume ratio falls and this means that simple diffusion is not sufficient so active transport in necessary
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what are adaptations that animals have gone through for exchanging materials
having a large surface area, a thin membrane, an efficient blood supply to maintain a steep concentration gradient
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how do calculate surface area to volume ratio?
length x width ( surface area) : length x width x height ( volume)
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how are the lungs adapted for gas exchange
alveoli have a large surface area, a moist line for dissolving gases, very thin walls and a good blood supply which maintains a high concentration gradient.
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how are the small intestines adapted for exchange
villi are there to increase the surface area so that food is absorbed quickly into the blood, they have a single layer of cells and a good blood suppy.
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what are the variabl in the effect of sugar solution on plant tissue
dependent- the mass of the patato chip. independant - the difference in mass. controll- volume of solution, time and temperature
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how are fish adapted for gas exchange
gills have a large surface area with a rich blood supply
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how are leaves adapted for gas exchange
stomata allow for water vapor to diffuse in and out. plant roots have a large surface area which is useful for the uptake of water and mineral ions, the water constantly moves away from the roots which keeps a steep concentration graident.
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what is active transport
active transport is the movement of mineral ions from an area of low concentration to an area of high concentration against a concentration gradient. Active transport needs energy for respiration to make it work. this energy is called atp
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how does active transport stop us from starving?
when there is a lower concentration of nutrients in the gut than in the blood this means that the concentration gradient is in the wrong way.
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what are chromosomes?
chromosomes are the genetic material
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What do chromosomes carry
they control your personal characteristics such as hair colour
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how many chromosomes do we have
23 pairs- 46 chromatid
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name the stages of Mitosis
Prophase, Metaphase, Anaphase, Telophase
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what is prophase
chromosomes become visible and nuclear envelope disappears
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what is metaphase
chromosomes arrange themselves at centre of the cell, spindle fibres form
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what is anaphase
chromatide migrate to opposite poles and they are oulled apart by spindle fibres
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what is telophase
chromatide reach poles and are now chromosomes . no longer visible . the nuclear envelope reforms and spindle fibres disintergrate
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what is interphase
this is the stage before cell division and this is the time where the cells increase in mass and continue normal cell activies. this is when they increase sub-cellular structures such as mitochondria and ribosomes
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do all plant cells undergo mitosis
no bacterial cells repoduce by binary fission
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what are the three stages of a cell cycle
interphase, mitosis and cytokynesis( true cell division)
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what is binary fission?
a type of simple cell divison that only bacteria undergo
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what are the four steps of binary fission
1. the circular DNA and plasmids replicate 2. the cell gets bigger and the DNA strands move to opposite poles 3. the cytoplasm divides and new cell wall form 4, the cytoplasm divides and two diploid daughter cells are produced. each cell has one copy
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what are the four steps of binary fission pt2
of the circular dna but a variable number of plamids
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what causes bacteria to divide quicky
warm temperature and lots of nutrients, but if those diminish the cell will die as it will stop dividing
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what are stem cells?
They are cells that are undifferenciated that can make more cells depending on what instructions they have been given
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where are stem cells found
human embryos and in bone marrow
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What can stem cells be used for
they can be used to create clones and for medicine or research
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how can stem cells be used to treat disease?
Paralyzed people can have nerve cells and diabetics can have insulin producing cells
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what are the risks with using stem cells?
Stem cells grown in a lab could be contaminated with a virus that when given to a patient could make them sicker.
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Why are people against stem cell research?
they feel that embryos shouldnt be used for research as it is a potential life
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why are people for stem cell research?
The embryos used a re often unwanted and from fertility clinics which mean that they were going ot go into the bin anyways
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how are plant stem cells useful for plants
the meristems can differentiate throughout their lives and produce clones cheaply an quickly.
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how are stem cells useful for farmers
this can help to grow disease resistant plants that are identical
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how do you find the area of a colony
area = πr²
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what is sterile technique
the pratical should be carried out near a safety flame to avoid unwanted microorganisms. Also cleaning the inoculating loop is important to kill any bacteria
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how does the structure of leaves allow gases to diffuse in and out of cells
Carbon dioxide diffuses into the air spaces where it then diffuses into the cells. Water vapour and oxygen also diffuse out thorugh the stomata. the flat leaf increases surface area .
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Other cards in this set
Describe Cell membrane
Controls which substances enter and exit the cell