B2 Flashcards
What is diffusion
Diffusion is the net movement of particles from an area of high concentraion to an area of low concentration
What is osmosis
Osmosis is the net movement of water molecules from an area of high water potential to an area of low water potential
Across a semi-permeable membrane
What is a hypertonic soloution
A hypertonic solution has a high solute concentration and a low water concentration
What is a hypotonic soloution
A hypotonic solution has a high amount of water to a low amount of solute
What happens when a plant cell is placed in a solution with a low / high solute concentration
Lower concentration - Water is taken up by the plant cell (as there is more water putside than inside), causing the turgor pressure to increase - makes the cell firm/turgid
Higher concentration - Water leaves the plant cells (as there is a lower concentration of water outside than inside), causing the turgor pressure to fall. The cell becomes flaccid and eventually the cell contents/membrane are pulled away from the plant cell wall. This is called a plasmolysed cell
What is turgor pressure.
The force within a cell which pushes the membrane against the cell wall
What happens when an animal cell is placed in a solution with a low / high solute voncentration
Low concentration - cell takes up water and swells (may burst) the cell has lysed (lysis)
High concentration - cells loose water, and become crenated
Occurs via osmosis
What is a single / double circulatory system
Single - blood passes through the heart once per full cycle of the body, the heart has 2 chambers and low pressure (can be found in fish)
Double - blood passes through the heart twice per full rotation of the body, the heart has 3-4 chambers and has high pressure (present in people)
What do arteries veins and capillaries do?
Arteries - carry blood away from the heart in high pressure
Veins -carry blood towards the heart (lower pressure)
Capillaries - semipermeable connections linking arteries and veins, in tissues and organs
What are the properties of arteries?
-Smaller lumen to maintain high pressure
-Thick layer of smooth muscle (for contractions)
-Elastic tissue which can withstand high blood pressure (allows for stretch and recoil)
- Thick outer layer for lots of strength (to withstand high blood pressure
- Smooth endothelium to ease blood flow
What are the properties of veins?
- Wide lumen as blood pressure is lower and, a wider lumen makes blood flow easier
- Valves prevent backflow
-Less muscle and tissue as less pressure
-Thin outer walls as blood pressure is lower
-Endofelium is smooth so blood flow is easier
What are the properties of capillaries
- one cell thick (responsible for blood exchanhe)
-10micrometes - more cappilaries in the arteries
What is an open circulatory system and a closed circulatory system
Closed system contains blood vessels
Open systems dont, and can be found in insects
What is mass flow?
The movement of fluid down a concentration gradient (high to low)
What is found in a circulatory system
Transport medium (e.g blood)
A pump (the heart)
Blood vessels (closed only)
What is on the left of the heart and what does it do
-Aorta - takes blood to the rest of the body (main artery)
-Pulmonary vein - takes blood from the lungs to the heart
-Left atrium- first heart chamber of the heart
-bicuspid valve - prevents backflow from the left ventrical to the left atrium
- left ventrical - second chamber
- semi lunar valve prevents backflow from the aorta to the left ventricle
What is on the right side of the heart and what does it do
Vena carva - takes blood from the body to the heart (main vein)
-Pulmonary artery- takes blood from the heart to the lungs
-Right atrium- first heart chamber of the heart
-tricuspid valve - prevents backflow from the right ventricle to the right atrium u
- right ventricle - second chamber
- semi lunar valve prevents backflow from the pulmonary artery to the right ventricle
Why is there more muscle on the left of the heart than the right
Blood needs to have a high pressure leaving the heart to the rest of the body. As the distance between the heart and the body is greater than the heart of the lungs, the left side (which takes blood to the rest of the body) has more muscle which will produce a greater force when it contracts, ensuring the pressure stays higher for longer and the blood will travel quicker.
Also the pressure cant be too high going to the lungs as the capillaries will burst
What makes up the Plant transport system?
Vascular bundle - phloem and xylem (phloem on the outside)
Cambium
Pith - stores transport nutrients
What is the purpose and structure of the xylem?
- It takes water and mineral ions to the leaves (from the roots)
- it is made of outer dead cells (organelles removed) to create a greater area to transport
- moves using mass flow
-xylem vessel elements are stacked to form xylem vessels - Lignin makes the xylem waterproof and gives it support
- no end between cells for a constant flow
What is the purpose and structure of the phloem
- It has two way movement (source (leaves) to sink (further down the plant))
- carries water but predominantly sucrose, and other organic molecules like proteins
- made of living cells (with most organelles removed) with perforated ends (sieve plates) which ease flow
- one direction at a time
- made from sieve tube elements
- has sieve played to ease flow of water
What is translocation?
Translocation is the movement of mass flow in the phloem
Sucrose will be pulled further down the plant to be stored (e.g in the roots)
What is transpiration?
Transpiration is the loss of water from a plant through evaporation
What is the transpiration flow/stream?
The continuous unobstructed flow of water from the roots to the leaves
Limiting factors of transpiration
Light intensity - More stomata are open so more co2 enters the cell, transpiration rate is quicker
Air movement - water molecules are pushed away from the stomata making the concentration gradient steeper, so transpiration happens at a greater rate
Humidity - More water molecules in the air surrounding the stomata, concentration gradient is decreased so rate of transpiration is lower
Temperature - water vapour has a higher kinetic energy, rate of water leaving is quicker
Purpose and special structure of a guard cell
-Guard cells control the opening and closing of stomata.
-They have thin outer walls
Its Thick inner walls join to close stoma
-stoma closes when there cell is flaccid
Stomata closes at night as photosynthesis is not taking place
What is a concentration gradient
Difference in correlation between two regions
What factors affect the rate of diffusion and how do they affect it
The distance particles need to move - the less space they must move the faster the reaction
The concentration gradient - the steeper the concentration gradient the greater of net movement of particles (in an attempt to gain equilibrium)
The surface area - a greater surface area allows more particles to diffuse at one guven time.
What is an isotonic solution
A solution where solute and solvent concentration is equal
How do you calculate percentage change
((New result - original result)÷ original result) ×100 = ∆%
What is active transport
The movement of molecules and ions against the concentration gradient (low to high) through the use of carrier proteins and ATP
What is a carrier protein
Special proteins which stretch across a cell membrane
A specific molecule required to a cell binds to a specific carrier protein
Energy is needed to rotate the carrier protein, so the molecule can be deposited into the cell
Name an example of active transport osmosis and diffusion in plants and animals
Plants:
Osmosis - absorbs water from the soil
Diffusion - absorbs Co2 and 02 through the stomata
Active transport - uptake of mineral ions from the soil into root hair cells
Animals:
Osmosis - Bringing water into any cell
Diffusion - During respiration oxygen diffuses into the blood (in the lungs)
Active transport - ions being taken out of the filtrate into the blood in the kidneys
What is mitosis
A process in which cells divide into genetically identical daughter diploid cells
Used for growth and repair
What is the cell cycle and its stages
A cycle consisting of 5 stages (although the 4th and 5th are considered as one)
G1(growth stage 1) - cell go through most of their growth + organelle replication+ protein synthesis
S (synthesis stage) - most of DNA replication occurs +
G2 (Growth stage 2)- (same as G1) cells go through further growth + preperation for mitosis
Mitosis - cell replication
Cytokinesis - cytoplasmic Division into two genetically identical daughter cells
What are the 4 main stages of mitosis
Prophase - The nucleus breaks down and chromosones condense. Spindal fibres form
Metaphase - The chromosones line up on the equatir of the cell
Anaphase - The chromatids ate pulled apart and chromosomes are pulled by the spindle fibres to opposite poles of the cell
Telophase - the chromosones at each end de-condense and the nuclei forms and the cell pinches and spindle fibers break down
Cell begins to pinch
What is interpahse
A phase of the cell cycle containing G1 S and G2
What is a stem cell
A unspecialised cell which can divide and differentiate into different specialised cells
What is a pluripotent stem cell
Can divide and differentiate into many stem cell (significantly more than multipotent)
What is a multipotent stem cell
Can divide and differentiate into more than one cell type but its more limited than pluripotent
What is a specialised cell
A cell that has divided and differentiated into a cell, giving it a specific function
They allow an organism to work more efficiently
How have fat cells adapted
These specialised cells have a small layer of cytoplasm surrounding the fat reservoir.
They can expand to 1000× their original size
How has the sperm cell adapted
Has a flagellum - propels the sperm cell to the ovum
Lots of mitochondria - more respiration so more energy transferred so movement is faster
Acrosome - stored digestible enzymes which break down the ovum outer layers - allowing the sperm to transfer its generic material
How have red blood cells adapted
They are biconcave which gives them a greater surface area to volume ratio - oxygen diffuses into the cell quicker
Packed full of haemoglobin
No nucleus so more room for haemoglobin
What are palisade cells
Specialised cell for carrying out photosynthesis
They ate packed full of chloroplasts, and have a regular shape to maximise photosynthesis
What are Ciliated cells
They can be found in your airways
Have small hairs which swipe mucus away from your lungs to the back of your throat
As bacteria and dirt is trapped by the mucus, this ensures your lungs are protected
Where are stem cells found in plants
In the meristems - the growing region of a plant
What are ASC
Adult stem cells these are multipotent stem cells
What are ESC
Embryonic stem cells - they are pulirpotent
Advantages and disadvantages of using ESCs
A:
Easy to get
Can make any specialised cell
Can save lives
D:
Only limited number
Could be a potential life (taken from embryos)
Could be rejected
Advantages and disadvantages of ASCs
A:
Unlimited number
Can save lives
Less issues with donation
D:
Hard to obtain
Only make specific stem cells
Risk of rejection
Asc’s being taken is uncomfortable
Taking cells gives a higher riks of cancer / infection
What is surface area to volume ratio
The surface area per unit of volume
Why is surface area to volume ratio important in diffusion
The larger the surface area : volume ratio the faster the rate of diffusion
The larger the organism the slower the surface area to volume ratio
Why are alveoli used in the lungs
To increase the surface area to volume ratio, so oxygen can diffuse into the blood faster
How else is diffusion in the lungs sped up
The walls between the alveoli and blood are one cell thick
Alveoli is curved = greater surface area
This means difussion is quicker
What is the point of transport mediums
Carrying materials to where they are needed
What are the two main types of circulatory systems
Closed - transport medium is transported through blood vessels
Open - transport medium can flow anywhere in the body
How does blood flow through the heart
The vena cava brings deoxygenated blood to the heart, where it first flows into the right atrium.
The blood flows through into the right ventricle and the tricuspid valve prevents backflow into the right atrium
Next the blood flows into the pulmonary artery and the semi-lunar pulmonary valve prevents backflow into the right ventricle.
The pulmonary artery takes blood to the lungs where it becomes oxygenated
This oxygenated then flows into pulmonary veins, which brings it into the heart
From this vein the blood flows into the left atrium.
The bicuspid valve then prevents backflow from the left atrium to the left ventricle .
Once in the left ventricle the blood flows past the semi lunar aortic valve, and to the aorta
It is then pumped around the body
Vena cava → right atrium → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → aorta
What is blood made up of
Red blood cells - carry oxygen, fit through the lumen of capillaries one at a time
White blood cells - fight diseases by making antibodies or change shape to engulf micro organisms
Plasma - most materials are carried by the plasma (inc red and white blood cells) such as digested food (amino acids and glucose) waste products (luke carbon dioxide) hormones and antibodies
Platelets - help to clot the blood
What are vascular bundles
The xylem and the phloem
What does the cross section of a stem look like
The middle is made of pith - packing/filler
Then surrounding the pith is the thin cambium
On the Cambium are vascular bundles
The xylem is on the inside (closer to the pith) the phloem is on the outside. They both touch the cambium
What is the cohesion tension theory
It is how water is pulled up the xylem
Water molecules bond with other water molecules through hydrogen bonds (cohesion) (like for like bonding)
Water molecules then bond to the wall of the xylem (adhesion)
Water is pulled up the xylem under pressure
What is transpiration
Loss of water from the leaves of a plant
How is water lost from leaves
When the stomata are open water evaporates from cells inside the leaf to air spaces within the cell.
This creates a concentration gradient between the inside of the leaf and the surrounding air
Water vapour then diffuses out of the leaf
Loss of water reduces the pressure in the xylem vessels (in the leaf)
As pressure is reduced water will travel back up the xylem to the leaves
How is uncontrolled water loss from a plant prevented
When the stomata are open, water evaporates and fills the air spaces in the leaf, the water vapour can then diffuse out of the cell.
The stomata are open when guard cells are turgid
And to close them they must become flaccid
This is done by increasing the concentration of potassium (solute) outside of the cell, so water is transported out of the guard cell into the solution, causing it to become flaccid and closing the stomata.
(The potasium is transported from the roots to the shoots through the xylem)
How does light intensity affect the rate of transpiration
Increased Li means more stomata are open (so more co2 can enter)
More open = more water leaving the cell
How does air movement affect the rate of transpiration
Water vapour pushed away from leaves
Concentration gradient between air and leaves increase
Greater rate of diffusion
More water leaves
How does humidity affect the rate of transpiration
Increase in humidity = increase in water particles near stomata
Decreases the concentration gradient
Less water leaves the leaf
How does temperature affect the rate of transpiration
Water vapour has a higher average kinetic energy
Rate of evaporation increases
So the concentration gradient in the plant and outside the plant increses
Rate of transpiration increases
How do stem cells differenciate
They activate certain genes that are specific to their needs
E.g when stem cells differentiate into beta cells the insulin gene is activated
Why do cells have different purposes but the same dna
All cells contain the same DNA, just different genes are activated and others are deactivated
What does it mean if a gene is activated / turned on
Transcription and translation can occur at this gene
Why are stem cells important
They allow the organism to be more efficient
What muscle contracts, pushing blood around the heart
The cardiac muscle
How is the mitochondria adapted
It is folded, giving it a higher surface area to volume ratio
Why do blood vessels have elastic fibers
This allows them to maintain their shape when the smooth muscle contracts and relaxes
The fibers allow the blood vessel to stretch and recoil, without any damage
What type of reaction is aerobic respiration
It is an enzyme controlled exothermic reaction
What is the difference in function between adult stem cells and embryonic stem cells
Adult stem cells:
Are used for replacing damaged / dead stells
Embroynic stem cells
Are used for growth and development
What is used to manage carbon dioxide in photosynthesis experiments (prevent it from being a limiting factor)
You react sodium hydrogencarbonate with water
This produces excess carbon dioxide, ensuring that it will not be a limiting factor
What do you need to do before counting the bubble in the photosynthesis experiment (pondweed)
Allow the bubble to acclimatise
(Allow them to be produced at a steady rate)
