B1 Flashcards
How many meters in a km?
1000m
How many cm in a m?
100cm
How many mm in a cm?
10mm
How many μm (micrometers) in a mm?
1000μm
How many nm (nanometers) in a μm (micrometer)
1000nm
What is the average size of a plant cell?
10-100μm
What is the average size of an animal cell?
10-30μm
List parts of a microscope?
Eyepiece
Arm
Clips
Course Focusing Wheel
Fine Focusing Wheel
Nose Piece
Objective Lens
Stage
Condenser
Light
Base
How to focus a microscope?
Turn course focusing wheel until cells come into focus, then turn fine focusing wheel until you can clearly see the cells
What is the Image?
What you see when you look down the microscope
What is the Object?
The real sample you’re looking at
What is Magnification?
Enlarging the apparent size of the object, not its physical size
What magnification does the eyepiece already have?
x10
How to find the magnification?
Whichever magnification the objective lens has (x4, x10 or x40) times by 10 as the eyepiece already has a x10 magnification.
The IAM triangle
I A Image = Actual Size ÷ Magnification
M
What is Resolution?
The ability to distinguish 2 points/objects that are very close to each other
What does a high resolution mean?
You can see more detail
What does low resolution mean?
You can see less detail
How do light microscopes work?
What are their magnification?
Resolution?
Image?
Samples?
Light passes through cells then reflects through lens. Lens bends light towards your eye which magnifies it.
3 lenses: x4, x10, x40. Eyepiece has magnification of x10
Low, details are blurry
In colour
Dead or alive
How do electron microscopes work?
Magnification?
Resolution?
Image?
Samples?
Beam of light replaced by ray of electrons. Lenses replaced by coil shaped electromagnets.
x1000000
High, details are clear
Shows as a micrograph (photo.) In black and white
Have to be held in a vacuum for electrons to pass through easier so samples are dead
List plant cell organelles and their functions?
Vacuole: Chemical store, keeps cell rigid and stores cell sap
Cell Membrane: Regulates the transport of materials entering and exiting the cell
Cellulose Cell Wall: Gives strength and structure to the cell
Nucleus: Stores genetic information and controls the cell
Ribosomes: Where proteinsynthesis occurs
Chloroplasts: Absorbs light so photosynthesis can happen. Contains chlorophyll
Mitochondria: Releases energy through respiration
Cytoplasm: Where other organelles are held and where chemical reactions occur
List of animal cell organelles and their functions?
Cell Membrane: Regulates the transport of materials entering and exiting the cell
Nucleus: Stores genetic information and controls the cell
Ribosomes: Where proteinsynthesis occurs
Mitochondria: Releases energy through respiration
Cytoplasm: Where other organelles are held and where chemical reactions occur
Why don’t animal cells have a vacuole?
Animals don’t need to store water and can move around to obtain their food
Why don’t animal cells have chloroplasts?
Animals don’t photosynthesise
Why don’t animal cells have a cell wall?
It would make it very difficult for them to move
Characteristics of a Prokaryotic Cell
Cell wall NOT made of cellulose
NEVER have mitochondria or chloroplasts
Some have a protective slime capsule around outside of the cell wall
Some have a flagellum to propel themselves
Have plasmids (extra genes) for antibiotic resistance
NO NUCLEUS
DNA floats in cytoplasm
Can efficiently reproduce
No membrane bound organelles
Around 0.2-2.0 μm
Bacteria are examples of Prokaryotic Cells
Characteristics of a Eukaryotic Cell
Has a nucleus
Has a cell membrane
Has cytoplasm
Has DNA organised in chromosomes
Has membrane bound organelles
Around 10-100 μm
Examples are animal cells, plant cells and fungi
As an organism develops…
Cells differentiate to form specialised cells
Some specialised cells work individually, but some…
Are adapted to work as part of a tissue, organ or organism
Examples of specialised cells
Nerve Cells
Muscle Cells
Sperm Cells
Root Hair Cells
Photosynthetic Cells
Xylem Cells
Phloem Cells
Nerve Cells
And Adaptions
Specialised to carry electrical impulses around the body
Provide a rapid communication system between body parts
Lots of dendrites to make connections to other nerve cells
An axon carries the nerve impulse from one place to another
Synapses pass impulses to another cell or in between a nerve cell and muscle using transmitter chemicals
Lots of mitochondria to provide the energy needed to make the transmitter chemicals
Muscle Cells
And Adaptions
Specialised cells that can contract and relax in pairs to move the bones of the skeletons so vertebrates can move.
Smooth muscle cells form one of the tissue layers in the digestive system to contract and squeeze through your oesophagus
Contains special proteins that slide over each other making the fibres contract
Lots of mitochondria to transfer energy needed for the chemical reactions that take place as the muscle contracts and relaxes.
Can store glycogen (a chemical that can be broken down and used in respiration to transfer energy needed for the fibres to contract.)
Sperm Cells
And Adaptions
Contain the genetic energy from the male parent and need to travel through the female reproductive system
Long tail to help it move
Middle section full of mitochondria which transfers the energy needed for tail to move
Streamline to move faster
Acrosome stores digestive enzymes to breakdown outer layers of the egg
Large nucleus containing the genetic info
Root Hair Cells
And Adaptions
Helps the plant take up water and mineral ions efficiently. Close to xylem tissue which carries water and mineral ions up into the rest of the plant. Mineral ions moved into the cell via active transport. Found close to the tips of growing roots
High SA available for water to move into cell via osmosis
Large permanent vacuole which speeds up movement of water by osmosis from the soil to the root hair cell
Has mitochondria to transfer energy needed for active transport of mineral ions into the cell.
Photosynthetic Cells
And Adaptions
Cells that can carry out photosynthesis to make their own food
Has chloroplasts containing chlorophyll which traps the light needed
Positioned in continuous layers and outer layers of the stem of a plant to absorb as much light as possible
Large, permanent vacuole that keeps the cell rigid as a result of osmosis
Xylem Cells
And Adaptions
The transport tissue in plants that carries water and mineral ions from the roots to the leaves and shoots. Important in supporting the plant
Alive when first formed but a chemical called lignin builds up in spirals in the cell walls, causing cells to die and form long hollow tubes that allow water and mineral ions to easily move through them, from one end of the plant to the other.
The spirals and rings of lignin makes the cells very strong and helps withstand the pressure of water moving up the plant and helps to support the stem
Phloem Cells
And Adaptions
Specialised transport tissue that carries the food made by photosynthesis around the plant. Forms tubes but they DON’T become lignified and die like xylem cells. The dissolved food moves up and down the phloem tubes to where it is needed
Cell walls between cells break down to form sieve plates to allow water carrying dissolved food to move freely up and down the tubes to where it’s needed
They lose a lot of their internal structures but are supported by companion cells to keep them alive
The mitochondria of the companion cells transfer the energy needed to move dissolved food up and down the phloem
What is Diffusion?
Diffusion is the NET MOVEMENT of particles FROM an area of HIGH CONCENTRATION to an area of LOWER CONCENTRATION, down the CONCENTRATION GRADIENT until EQUILIBRIUM is reached
What factors affect diffusion?
Concentration gradient. Steeper gradient = higher rate of diffusion
Temperature. Higher temperature gives particles more energy = particles move faster = higher rate of diffusion
Surface Area. More space for particles to diffuse in and out at a time = higher rate of diffusion
Examples of diffusion in living organisms
Oxygen needed for respiration passes from the air in your lungs into the red blood cells through the cell membrane by diffusion
Oxygen diffuses from red blood cells to where it is needed
Carbon dioxide diffuses from body cells to red blood cells then into the lungs to be removed from the body.
The diffusion of oxygen and carbon dioxide happens in opposite directions. This is GAS EXCHANGE
What is Osmosis?
Osmosis is the NET MOVEMENT of WATER molecules FROM an area of HIGH WATER CONCENTRATION (dilute) to an area of LOW WATER CONCENTRATION (concentrated) through a SELECTIVELY PERMIABLE MEMBRANE, until EQUILIBRIUM is reached.
What factors affect Osmosis?
Temperature. Increased temperature = increased rate of osmosis
Particle Size. Small particles can pass through membrane quicker. Smaller particles = higher rate of osmosis
Surface Area. Higher Surface Area = higher rate of osmosis
Size of concentration gradient. Steeper gradient = higher rate of osmosis
What does Isotonic mean?
If the concentration of solutes in the solution OUTSIDE of the cell is THE SAME as the INTERNAL concentration.
What does Hypertonic mean?
If the concentration of solutes in the solution OUTSIDE of the cell is HIGHER than the INTERNAL concentration, so WATER MOVES OUT of the cell. The cell becomes PLASMOLISED.
(inside cell is more dilute than outside the cell)
What does Hypotonic mean?
If the concentration of solutes in the solution OUTSIDE of the cell is LOWER than the INTERNAL concentration, so WATER MOVES INTO the cell. The cell may burst.
(outside of cell is more dilute than inside)
What is Active Transport?
Active Transport is the movement of molecules AGAINST the CONCENTRATION GRADIENT, FROM an area of their LOW CONCENTRATION, TO an area of their HIGH CONCENTRATION. This REQUIRES ENERGY from the cell, which is transferred by mitochondria.
What does Active Transport enable cells to do?
Absorb ions from dilute solutions
Move substances (e.g. sugar and ions) from one place to another
Sugar to be absorbed out of your gut and kidney and into your blood to be used for respiration
Factors that affect Active Transport
Temperature. Higher temperature = higher rate of active transport
Concentration gradient. Steeper gradient = higher rate of active transport
How do Plants rely on Osmosis?
To support their stems and leaves
When water moves into cells, the cytoplasm is pressed into the cell wall, which causes pressure known as turgor, which makes the cells go rigid and hard.
Plants need the solution surrounding their cells to be hypotonic, so water moves into their cells
What are Exchange Surfaces?
Specialized structures that allow for the exchange of materials to happen
Features of Exchange Surfaces
Large SA: increases rate of movement
Thin Membrane: Shorter diffusion distance
Moving Blood Supply: Keeps concentration gradient high
Moist Membranes: Helps gases dissolve and diffuse faster
Method for the Potato Experiment
1) Cut 5 potato pieces to the same length using knife, tile and borer
2) Place chips onto filter paper to soak up excess water
3) Record mass of each chip
4) Place chips in different sucrose solutions
5) Place a bung on top of each tube
6) Leave the tubes overnight
7) Dry the chips and re-weigh them
8) Calculate the % change in mass
9) Plot % change in mass and sucrose solution onto a graph and where the line crosses the x axis is the concentration of potato cytoplasm
Equipment for Potato experiment
Potato
Knife
Tile
Borer
Ruler
Filter Paper
Mass Balance
Why do you use the equipment for potato experiment?
Cut chips on white tile: to not cut yourself
Same sized cork borer: so chips have same dimensions
Same potato: condition of potato are the same. same cytoplasm conc.
Remove potato skin: potato skin cells are different
Soak up excess water: so doesn’t interfere with results
Same volume of sucrose solution: fair test
Use bung: Prevents evaporation
