B1 Flashcards
draw the graph from metre to nanometre
m–>x1000–>mmx1000–>micrometrex1000–>nm
differences between light and electron microscope
Light-4
electron-6
Uses electrons
More expnsive
Higher resolution
Not mobile
Two types:
Scanning EM
Transmission EM
Scanning - 3D images but lower magnification
Transmission = 2D but higher resolution and magnification
Uses light
Cheaper
Lower resolution
Mobile
Definition of resolution
Resolution = the ability to distinguish between two points
write microscope formula
I=AM
Image Size = Actual Size x Magnification
The unit for I and A MUST be the same when using this equation
draw and label an animal and plant cell
check google-lablled animal and plant cell GCSE
function of nucleus
Nucleus - controls the chemical reactions in the cell and contains genetic information
cytoplasm’s function
Cytoplasm - a jelly-like substance where organelles are suspended in, and the site of chemical reactions in the cell
function of mitochondria
Mitochondria - the site of aerobic respiration
function of ribosome
Ribosome - the site of protein synthesis
function of cell membrane
Cell Membrane - controls what enters and leaves the cell
function of cell wall
Cell Wall - made of cellulose. Supports the cell.
function of vacuole
Vacuole - Filled with cell sap. Stores water and keeps cell rigid to support the plant
definition of prokaryotic cells
Prokaryote = (before the nucleus) - the genetic material is NOT enclosed in a nuclear membrane - so the genetic material is loose
definition of eukaryotic cells
Eukaryote = (true nucleus) - the genetic material in the cell is enclosed in a nuclear membrane
example of prokayotic cells-1
bacteria
examples of eukaryotic cells
all other type of cells, eg animal cell, plant cell, fungi, protisits
Definition of Plasmoids
circular rings of DNA.
Definition of Flagella
a long protein strand that lashes around
Definition of Differentiating
when a cell changes to gain adaptation that help it carry out its function
Draw a nerve cell diagram
Search google for labelled nerve cell diagram
what do nerve cells do?
Nerve cells/Neuron carry electrical impulses around the body
what are dendrites and what do they do?
Nerve cells/Neuron carry electrical impulses around the body
where is the axon and what does it do?
Axon carries the impulse from one place to another
longest axon in the body
spine to big toe
function of myelin sheath
Myelin sheath for insulation
function of synapses
Synapses to pass the impulses to another nerve or muscle using chemical transmitters
function of mitochondria in nerve cell
A lot of mitochondria to respire aerobically in order to release energy to be used to make chemicals (neurotransmitters)
how do muscle cells work?
Muscle cells contract and relax in pairs to move the bones in the skeleton
describe the process of peristalsis(digestion of food)
Muscle cells in the digestive system contracts to squeeze the food through the gut - peristalsis
why do muscle cells have lots of mitochondria
many mitochondria to release energy via aerobic respiration to be used in muscle contraction
what is glycogen and its function
muscle cells can store glycogen - used in respiration by mitochondria - Glycogen is a type of storage for glucose
Draw a sperm cell
google search- labelled sperm cell GCSE
adaptations of a sperm cell
4 points
A long tail - helps it swim long distances to the egg to fertilise–
Middle section full of mitochondria - to release energy via aerobic respiration to be used for the tail to move–
Acrosome stores the digestive enzymes which break down the outer layer of the egg–
Large nucleus containing genetic information
state function of root hair cell
3 points
1)Used to take in water and mineral ions from the soil
2)Root hair cells are located relatively close to the xylem which moves water and mineral ions into the plant
3)Ions, and sometimes water, are taken in via active transport
state adaptations of root hair cells
1)Root hair - greatly increases SA:V for water to move into cells
2)Vacuole to speed up osmosis of water into the cell
3)Many mitochondria - for lots of aerobic respiration to release lots of energy to be used for active transport
what is a photosynthetic cell
literally a fancy way of saying plant cell
what is the function of photosynthetic cells
to carry out the process of photosynthesis to make glucose for the plant
name 3 adaptations of root hair cells
1)Contains chloroplasts made of chlorophyll - chlorophyll is a green pigment which absorbs light energy to be used in photosynthesis
2)Positioned in continuous layers in leaves and outer layers of stem - absorbs the maximum light energy
3)Large vacuole - keeps cells rigid as a result of osmosis - this supports the stem (gets leaves closer to the source of light - the sun), and helps the leaves remain spread out - this allows it to absorb as much light as possible
what is the function of xylem
Function: Xylem is a transport tissue in plants for water and mineral ions from roots to shoots, and is important in supporting plants
How is xylem formed:
Cells that are alive lign up end to end to form a tower. The membranes and cell walls between these cells dissolve, and the cells die, leaving behind a hollow tube. Then, lignin spirals form within the cell wall.
name 1 adaptation of xylem
Lignin spirals - very strong and helps the xylem withstand the high water pressure. This also helps the xylem support the plant
what is the function of phloem
Function: carries glucose made by photosynthesis
how are phloem cells formed
Made of phloem cells that also line up end to end like in xylem, however these don’t die
definition of diffusion
Diffusion = the net, passive movement of gas/solid particles down a concentration gradient
define net movements
Net movement = the overall movement. Particles move in both directions, but OVERALL there is movement from one area to another
how does size affect SA:V ratio
The bigger an object, the smaller the SA:V ratio - a mouse has a very large SA:V but an elephant has a very small SA:V - this is the reason that elephants’ ears are so big but so thin.
to help remember:
Think of a rich tea biscuit - it has a big circular SA but as it is thin it has a very low volume. So when you dip it in tea, a lot of tea is entering at the same point in time, because of the high surface area. However a shortbread finger is very narrow and also very wide. So it has a lower SA and a higher volume. This means at the same point in time, only a bit of the tea can enter the biscuit at once. Also as it has a high volume, the tea will take a lot longer to travel through the biscuit and soak it through as well.
What happens when there is a steeper concentration gradient
When there is a steeper concentration gradient (there is a very big difference in concentration between the two areas) diffusion occurs at a higher rate (it happens faster)
examples of diffusion
O2 and CO2 in gas exchange
glucose diffusing in and out of cells
Urea diffusing from liver cells into blood plasma
define Osmosis
Osmosis = net, passive movement of water particles down a concentration gradient, through a partially permeable membrane
define dilute
Dilute = lots of water
define concentrated
Concentrated = only a little bit of water
what is meant by isotonic
When the solution is isotonic to the cell, the concentration is equal in both (iso=equal)
what is meant by hypertonic
When the solutiotn is hypertonic to the cell, the concentration of the solutes outside the cell is higher than inside
what is meant by hypotonic
When the solution is hypotonic to the cell, the concentration of solutes outside the cell is lower than inside.
what is meant by a cell being turgid
When a plant cell is turgid = water has moved in, causing the vacuole to swell, and making the cytoplasm press against the cell wall
what is Active transport
Active transport = the movement of particles against the concentration gradient, requiring energy
what are some examples of active transport
Examples of active transport:
actively tranporting salt
(human body)actively transporting glucose INTO the bloodstream from the end of the small intestine
Plants actively transport water and mineral ions from the soil into the roots
(human body)Glucose is actively transported into the blood from the kidney tubules
Crocodiles have special salt glands that remove excess salt
how is cystic fibrosis caused
Cystic fibrosis a genetic condition caused by a recessive allele
what does cystic fibrosis do?
In cystic fibrosis, the cells cannot actively transport salt and water. This means that the person with the disease makes very thick and sticky mucus in the lungs, the gut and the reproductive system
what do cells that do alot of active transport have a lot of
mitochondria
Which factors affect diffusion
1 cell thick allowing shorter distances for diffusion
-Having a steep concentration gradient
-increasing temperature
increasing the SA:V
what are Villi
Villi = finger-like folds in our small intestine wall which create a larger SA:V for a faster rate of diffusion
