B1- Cell Structure and organisation Flashcards
Why are microscopes useful ?
-They provide magnification to observe cell strctures , see things human eye cant see.
-Enabless study of small and organsims diseases - so increases our understadning of cells and subceullar structures..
What do microscopes allow us to do ?
-Microscopes allow us to magnify .
What is the meaning of resolution?
The ability to distinguish between two sepearte points (clarity).
How do light microscopes work ?
Their advanatages
Light microscopes use a beam of light to form an object . Mangify several thousand times .
-ADV - releatively cheap
-Can be used anywhere
-Can be used to magnify live specimens .
Disadvanatges of light microscopes (1) .
Light microscopes have limited magnification (can’t view structure inside nucleus easily) as magnification is not powerful enough .
Disadvanagtage of light miroscopes (2)
Ligh microscopes have a limited resolution (images blurred even if you wer eto increase the magnification , can’t see fie detail).
Scientists realised if they wanted to view structures in detail , need an electron microscope .
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How does an electron microscope work ?
What are its advanatges ?
-Elecron microscopes use a beam of electrons to form images . Magnify objects up to around two million times
-They have a much greater magnification and resolution than light microscopes .
Disadvanatage of electron microscopes .
-Have to be large and are expensive .
-Have to kept in special temepatrue , pressure and humdiity controlled rooms .
How do you calculae magnification ?
Magnfiication =size of image /size of real object .
i over m*o
Magnficiation equation triangle .
size of image / magnification*size of real obejct .
do quesiton on sheet .
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Animals are eukaryotes , explain .
-Their Genetic maerial (DNA) is enclosed in a nucleus .
What are the structures in An animal cell ?
-Cell membrane
-Ribosomes
-Mitochondira
-Cytoplasm
-Nucleus .
What is the function of the nucleus ?
-Encloses the genetic material which controlls cells activity
Inside the cell is the cytoplasm , what is its function ?
-The cytoplasm is a water solution where chemical reactions take place (first stage of respiration )
The whole cell is enclosed in a cell membrane , what is its function ?
-The cell membrane controls the molecules that can enter and leave the cell .
What is the Mitochondria ?
-Where aerobic respiration takes place .
What are Ribosomes ?
-Very small so is mitochondira but ribosomes can be only seen with an electron microcosope.
-Site of protein synthesis .
Draw an animal cell .
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What are the strcutures in a plant cell ?
-cytoplasm
-Nucleus
-Cellmemrbane
-Cell wall
-Mitochondira
-Ribiosomes
-Chloroplast
-Vacuole
What structures do plants and animals both have in common
nucleus-
ribiosome
-mitochondria
-cell memrbane
*cyoplasm
Three structures only plants have ?
-Cell wall
-Vacuole
-Chloroplasts
-What are chloroplasts ?
Green structures that contain chlorophyll - are the sites of photosynthesis .
-What are cell walls ?
-Mde from cellulose , stengthens the cell .
-What are vacuoles ?
-Vacuoles are filled with a fluid called cell sap . Vacuole hellps to give the plant its shape .
Draw a plant cell .
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Meaning of a eukaryotic cell .
Eukarytoic cells contin their genetic materual (DNA) enclosed in a nucleus .
Example of eukaryotic cells .
Plants and animals.
Meaning of a prokaryotic cell
In prokaryoitc cells , the genetic material (DNA) is not enclosed in a nucleus .
-Prokarytoic cells are much smaller than eukaryotic cells .
Example of a prokaryotic cells and its characteristics .
-Bacteria
-Don’t have a nucleus so genetic material consists of a single loop of DNA .
-Or small rings of DNA known as Plasmids .
What functions do prokaryotic cells have .
Example bacteria
Genetic material loops
cytoplasm
cell membrane
slime capsule - bacteria have this to move and disguise in the white blood cells .
cell wall
plasmids-extra dna code for antibitoic resistance .
flagella- a long protein trand helps to move about cell .
Most animal cells are specialised , what does this mean ?
They have adaptations which help yhrm yo carry out a particular function .
When cells become specialised , what do scienitsts call them ?
differentation .
Three specialsied cells you need to know about .
-Sperm cells
-Nerve Cells
-Muscle cells
What is the job of a sperm cell ?
-The job of a sperm cell is to join with an ovum (egg cell) , We call this process fertilisation .
-During fertiisation , the genetic information of the voum and sperm combine ,
sperm cells contain their geentic information in the nucleus , sperm contint only half the genetic info of adult cells .
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Give one adaptaiton of a sperm cell .
Sperm cells have a long tail , which allows them to swim to the ovum . They are also streamlined , making this easier .
Give another adaptation of a sperm cell .
Sperm cells are packed full of mitochodri a , these provide the energy needed for swimming .
Give the last adaptation of a sperm cell .
Sperm cells containe enzymes which allow them to digest their way thorugh the outer layer of the ovaries .
What is the job of a nerve cell ?
The job of a nerve cell is to send electrical impulses around the body .
Give one adaptation of the nerve cell .
The nerve cell has a long axon , the axon carries electrical impulses from one part of the body to another .
Give another adaptation of the nerve cell .
The axon is covered in mgelin . Mgelin insualtes the axon and speeds up the transmission of the nerve impulse .
Give anotherr adaptation of the nerve cell .
The end of the axon has synapses . Synapses are junction which allow the impluse to pass from one nerve to another .
Give the final adaptation of a nerve cell .
The cell body of the enrve cell containts dendrites , these increase the surface area so that the nerve cells can connect more easily .
Draw a nerve cell with all adaptations.
question asked is how is nerve , muscle and sperm cell specialised .
What can a muscle cell do ?
Muscle cells can contract (get shoretr) .
How do muscle cells contract
To do this muscle cells contain protein fibres , which can change their length .
Give one adaptation of a muscle cell.
When a msucle cell contracts , these protein fibres shorten , decreasing the length of the cell .
Give another adaptation of a muscle cell .
Muscle cells are packed with mitochondria , to provide energy for muscle contraction .
-Muscle cells work together to form muscle tissue .
Give one adaptation of root hair cells .
Root hair cells have hairs , these increase the surface area of the root , so it can absorb water and dissolved minerals more effectively .
Root hair cells do not contain chloroplasts as they are underground .
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Draw a root hair cell .
need a root hair
cell wall
nucleus
vacuole .
Where are xylem cells found ?
Xylem cells are found in the plant stem .
What do xylem cells do ?
- They form long tubes .
-These long tubes carry water and dissolved minerals from the roots to the leaves .
Give one adaptation of a xylem cell .
Xylem cells have very thick walls containign ligngin .
-This provides support to the plant .
-However as the cell wass are sealed with lignign this scauses zyelm cells to die .
Give another adaptation of xyelm cells .
-So xylem cells don’t die , the end walls between cells have broken down . This means that the cells now form a long tube so water and dissolved minerals can flow easily .
Give the final adaptaion of xylem cells .
Xylem cells contain no nucleus , vacuole cytoplasm or cholorplast , hey have no intenral structure , making it easier for water and minerals to flow .
What do pholem cells do ?
Phloem tubes carry dissolved sugars up and down the plant .
Phloem containts phloem vessels what are they ?
Phloem vessel cell - thse have no nucleus and are limited to cytoplasm ,
Phloem conyaints two types of cceells what are they
pores and sieve plaates .
-The end walls of the vessels have pores called sieve plates . Both these features allow dissolved sugars to move through the cell interior .
Whhat is a companion cell , how does it work ?
Phloem
-Due to limited cytoplasm and mitochondria , each phloem vessel has a companion cell connected by pores .
-Mitochondira in the companion cells , provide energy to the phloem vessel cells .
Where can diffusion take place ?
Through the cell membrAane .
-One way molecules move in out of the cell is diffusion .
What is the meaning of diffusion ?
Diffusion is the spreading out of particles resulting in an overal movement from an area of high concentration to an area of low concentraition .
Why do cells need oxygen ?
Cells need oxygen for respiration which is carried out in the mitochondria .
Diffusion of oxygen into cells .
-Cells are surrounded by a high concentration of oxyegn
-. Oxygen is transported in the bloodstream from the lungs .
-Oxygen moves into the cell from a area of high concentration to an area of low concentration .
-The waste of product of oxygen is a waste gas Carondixodie .
Diffusion of carbondioxide .
-As carbondioxide is a waste porduc of oxygen , we have a higher concentration of carbondioxide inside cells than outisde .
-So carbondioxide moves out th cell by diffusion .
How does urea diffuse out of the cell ?
-Urea is a waste produc produced by cells .
-I diffuses out of the cells into the blood plasma and is excreeted by the kidneys .
Where can diffusion take place ?
Through the cell membrAane .
-One way molecules move in out of the cell is diffusion .
What is the meaning of diffusion ?
Diffusion is the spreading out of particles resulting in an overal movement from an area of high concentration to an area of low concentraition .
What is another factor that effects diffusion ?
Temperature : The higher the temperature , the greater the rate of diffusio. As the paricles have more kinetic energy and are moving faster .
Diffusion of oxygen into cells .
-Cells are surrounded by a high concentration of oxyegn
-. Oxygen is transported in the bloodstream from the lungs .
-Oxygen moves into the cell from a area of high concentration to an area of low concentration .
-The waste of product of oxygen is a waste gas Carondixodie .
Diffusion of carbondioxide .
-As carbondioxide is a waste porduc of oxygen , we have a higher concentration of carbondioxide inside cells than outisde .
-So carbondioxide moves out th cell by diffusion .
How does urea diffuse out of the cell ?
-Urea is a waste produc produced by cells .
-It diffuses out of the cells into the blood plasma and is excreeted by the kidneys .
What is one factor that effects the rate of diffusion ?
-Difference in concentration - known as concenrtation gradient .
-The greater the concentration gradient , the faster the diffusion that takes place .
If the concentration gradient is smaller …
The diffusion will be slower .
What is the final factor that effects diffusion ?
Surface area of membrane . The larger the surface area of the cell membrane , the greater the rate of diffusion .
What is osmosis ?
Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane .
What is a dilute solution ?
A dilute solution contains a high concentration of water .
What is a concentrated solution ?
A concentrated soulution contains a low concentration of water .
What is a partially permeable membrane ?
It allows some molecules to pss through but not all molecules .
What are the water concentrations in the cytoplasm ?
The cytoplasm of cells is a relatively concentrated solution . Contins relatively low concentrations of water .
What will happen if an animla cell was put into water ?
Osmosis will take place and water from outside the cell will come inside . This will cause the cell to expand even burst .
What will happen if we put an animal cell in a very concentrated solution ?
-If we put an animal cell in a very concentrated solution , the water will move out the cell by osmosis and the cell will shrink .
What will happen if we place a plant cell into water ?
-The water will move into the cell by osmosis and the cell will expand .
What prevents the plant cell from bursting in osmsosis .
In low concenrations , plant cell expands ,
-The cell wall prevents the plant cell from bursting . Instead the cell wall becomes swollen . Scientists call this TURGID .
What will happen if we put a plant cell into a concentrated solution ?
-Water moves OUT of the plant cell by osmosis , causing the cell to shink , scientists say the cell has become flaccid .
What is the first stage of the osmosis RP ?
-First we peel the potato . That is because the potato skin can affect osmosis .
What is the second stage of the osmosis RP ?
Use a cork borer to produce three cylinders of potato ..
-Uising a cork borer makes all the cyliinders the same diameter .
What is the third stage of the osmosis RP ?
-Use a scalpel to trim the cylinders to the same lengh . (around 3cm)
-Any shorter lengths may not be able to measure the efect of osmosis .
What is the fourth stage of the osmosis RP ?
-Measure the length of each cylinder using a ruler and the mass of each cylidner using a blance .
What is the fifth stage of the osmosis RP ?
Now place each cylidner into a test tiube . Add cmcubed of a 0.5 molar sugar solution to the first test tube .
What is the sixth stage of the osmosis RP ?
We then add 10 cm cubed of 0.25 sugar solution into the second test tube and 10 cm cubed of disitlled water to the third test tbe .
Why do we use distilled water ?
-We use distilled wayer , as it contains no dissolved substances that could effect the rate of osmosis .
What is the seventh stage of the osmosis RP ?
-Now leave the potato cylidners overnight to alllow osmosis to take place .
What is the eigth stage of the osmosis RP ?
-Next remove the potato cylidners gently and roll them on a paper towl to remove ay surface mositure .
(Don’t press ahrd , don’t wanna remove any water out of the cells ).
What is the ninth stage of the osmosis RP ?
-Measure the length and mass of the cylidners again
-Now we need to calculate the percentage change , how do we do that ?
Percentage change = change in value / the oirginal value times byb 100
Using the percentage change now a plot a graph .
-Mass change on the y axis
-Concenration of sugar solution on the x axis . .
On the sheet , what does the top of the graph show ?
-In water , the potato cylidner gains mass , as ater moves into it by osmosis .
On the sheet , what does the bottom of the graph show ?
In concentrated sugar solution , the cylinder looses mass as water moves out by osmossis .
On the graph , what happens where the line crosses the x axis ?
-There is no change in mass of concentration of sugar solution .
-Why is there no change in mass of concenration when crossing x axis ?
-That is because the concentration outisde the same cell is the same as the concentration inside . So no overall osmosis takes place .
Carrying on from that point , where i the approximate concentration insdie the cell ?
-The approximate concentration inside the cell is where the line crosses the x axis .
What if a cell needs to bring in a molecule , that is already at a high concentration insdie the cell ?
Use active transport .
What is active transport ?
Moves substances from a more dilute solution to a more concentrated solution (against the concentration gradient )
What does active transport require ?
Energy fromrr espiration .
What is the difference between active transport and diffusion ?
-Active transport , particles move against the concentraton gradient (diffusion moves doen the concentration gradient)
-Active transport requires energy from respiration (diffusion does not ).
Give example of acitve transport in humans .
-Cvity of small intestine , where food is difesed , can find molecules produced when food digested like sugar .
Give example of acitve transport in humans . (2)
-The concentration of sugars in the lumen is lower thn the sugars inside cells . So can’t diffuse in , insetad sugars are carried in by active transport .
Give example of acitve transport in humans .(3)
-Once transported into cell , sugars can be transported into blood and carried around the body .
-These cells have lots of mitochondria -to carry out respiration , providing energy needed for active transport .
Give an example of active transport in plants .
-Root hair cells foud in plants .
-Root hair cells transport ionsl ike mgensium into the plant from soil , needed to make chlorophyl in the leaves .
Give an example of active transport in plants .(2)
The cocnentration of ions in the soil is lower than the concentration insidie the root hair cell . Active transport moves ions into the cell .
Give an example of active transport in plants . (3)
-These ions can then be tranpsorted into xylem vessels and moved to the leaf .
-Root hair cells have a lot of mitochondria -providing energy for active transport .
Having huge surafce area for its volume is known as what ?
surface area :volume ratio
How to work out
surface area of a side ?
total surface area ?
and volume ?
LW
LWnumber of sides
LW*H
surface area to volume ratio =t otal surface area : volume .
-As organsims get larger …
why is this a problem ?
… the surface area : volume ratioo falls sharply .
Huge problem for multiceullar organsims as their surface area is not large enough for their volue .
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-Cells on the surface can get enoguh oxygen simply by diffusion .
-However , not enoguh oxyegn can difuse into the cells int he center of the organism .
-They are too far away from the surface .
Animals have solved this problem how ?
-Special structures foer as exchange with high surface area , lungs .
-Animals have a transport system that carry gases around body .
How do fishes breathe ?
-Get oxyegn from water .
-The oxygen rich water passes into the mouth . It then flows over the gills , where oxygen is transported into the bloodstream .
How do fishes breahe ? (2)
-The gills are covered ina very large number of fine filaments .
-This is where gasses pass in and out of the blood .
How do fishes breathe (3)
-Deoxygenated blood passes into the filament . Oxgen diffuses from the water into the blood .
-Oxygenated blood returns to the body .
Give one adaption of filaments to increase rate of diffusion .
Filaments give gills a massive surface area .
Give another adaption of filaments to increase rate of diffusion .
Filamnets also have a thin membrane , to provide a short diffusion pathway .
Give the fnal adaption of filaments to increase rate of diffusion .
The filaments have an efficent blood supply , to take the oxygenated blood away . This ensures the concentrtion gradient is always high .
-All these adaotations make diffusion as efficent as possible .
How to use a microscope s1
-Choose an objective lens with the lowest magnification .
-Put the slide on the stage of the microscope .
How to use a microscope s2
-Usinging the coarse focusing wheel m oisutuib tge sanoke as close to the lens as possible .
How to use a microscope s3
Whilst looking throught the eye peicce , use the coarse focusing wheel to m ove the sample into focus .
How to use a microscope s4
-Change it to the next magnification .
-Use the fine focus only to fucs the image .
