B2: Scaling Up Flashcards
describe the movement of particles
random-they move in all directions.However,more particles move from an area of high concentration to an area of low concentration than the other way round
what is going against/up the concentration gradient
the particles are moved from an area of low concentration to an area of high concentration.
what is going down/with the concentration gradient
the particles are moved from an area of high concentration to an area of low concentration.
what is diffusion
-overall movement of particles from a region of high to low concentration.
-moves down a concentration gradient and does not stop until the particles is the same everywhere
-concentration gradient at this point would be 0
what type of process is diffusion
passive-diffusion happens because of the ordinary motion of the particles,not because energy is transferred duting it
3 examples of diffusion in the body
-respiration-cells need glucose and oxygen.Blood transport these around your body.Glucose and oxygen then diffuse into the cells that need them.
-removing toxic waste products-some chem reactions that happen inside the cell make waste products and some are toxic.For example at high levels co2 is poisonous,so it diffuses out of respiring cells
-entering and leaving cells-particles pass through the cell membrane from a region of high concentration to low.
3 factors that affect the rate of which a substance diffuses
-distance
-concentration gradient
-surface area
how can you increase rate of diffusion with distance
decreasing the distance the particles need to move increases the rate of diffusion as it takes less time to travel a shorter distance
how can you increase rate of diffusion by concentration gradient
increasing the concentration gradient,hence making it steeper allows for a greater net movement of particles and allows for faster rate of diffusion
how does surface area affect rare of diffusion
increasing the surface area allows for more space for diffusion,so more particles can move in a period of time
osmosis
-diffusion of water molecules across a selectively permeable membrane and explains how water gets in and out of cells
what happens when a solute such as sugar is dissolved in water
water molecules cluster around the solute molecules and this leaves fewer water molecules free to diffuse other areas.
water potential
The concentration of free water molecules that have not clustered onto solute molecules.This means that pure water has the highest possible water potential as all of its water molecules are free to move with nothing to cluster onto
osmosis in terms of water potential
-osmosis is the movement of water molecules froma high water potential to a lower water potential down a concentration gradient.
-the greater difference in water potential,the greater rate of osmosis meaning when there are a low amount of water particles in an area, more water molecules from the region of higher concentration can enter faster and easier.
where does osmosis occur in plants
-surroundings are a less concentrated solution than water contents
-surroundings have the same concentration as cell contents
-surroundings are a more concentrated solution than cell contents.
what does it mean when the surroundings are a lesson concentrated solution than the cell contents
This means that the cell is placed in a dilute solution.It takes up water by osmosis.The pressure in the cell increases.The cell becomes firm or turgid
What does it mean by surroundings have the same concentration as cell contents
Cell placed into a solution with the sane concentration as its contents.There is no net movement of water.The cell remains the same
what dooes it mean that surroundings are a more concentrated solution than cell contents
Loses water by osmosis.The turgor pressure fails.The cell becomes flaccid(soft).Eventually the cell contents collapse away from the cell wall.This is called a plasmoylsed cell
osmosis in animal cells
cell has more wp than surroundings- takes up water,swells,and may burst.This is called lysis
same wp as surroundings with water contents-no net movement of water.The cell remains the same.
surroundings more than cell-Loses water by osmosis.Cell becomes crenated(it crinkles)
what is active transport
-allows cells to move substances from an area of low concentration to an area oh high concentration.
-As the particles are moving against their concentration gradient, energy must be transferred from an energy store.
3 key features of active transport
-particles are -transported(pumped)against a concentration gradient
-makes use of carrier proteins in the cell membrane
what does respiration have to do with active transport
-cells that carry out a lot of active transport contain many mitochondria.This means that they can respire rapidly to produce large quantities of ATP.
-The rate at which active transport can occur will depend on the rate of respiration to produce requaired ATP
what are carrier proteins
special proteins that span the width of the cell membrane.
-useful molecule binds with protein,rotates,lets molecule through and rotates back,step 2 and 3 using energy
when is active transport used.
active transport is used when a substance is moved against a concentration gradient
example of active transport
digestion-carbs turned into glucose in small intestine. Glucose actively transported across the blood stream through the villi(which increase SA of small intestine).
nerve cells-a carrier protein actively pumps sodium ions out of the cell.At the same time potassium ions are pumped back in.This potassium sodium pump plays an important role in creating nerve impulses
plants-minerals from the soil.Root hair cells use active transport to transport nitrate ions through the cell membrane and into the root cell for growth and protein.
why do body cells divide
to replace worn out cells
to repair damaged tissue,and to enable the organism to increase in size.
what is mitosis
the process by which body cells divide.Each cell divides to produce two identical daughter cells,which are genetically identical to the parent cell.Mitosis increases the number of cells in a multicellular organism
What is the process of cell growth and division and growth is called………..
cell cycle
4 stages of cell cycle
-DNA replication
-movement of chromosomes
-cytokinesis
-growth of daughter cell
DNA REPLCIATION:
1) DNA molecule ‘unzips’ forming two separate strands
2) DNA bases on each strand are exposed and free nucleotides in the nucleus line up agaisnt the strands following base pairings.
3)this forms DNA base pairs and when strand is complete,there are two identical molecules of DNA
MOVEMENT OF CHROMOSOMES
1) chromosomes line up accross centre of the cell
2) two identical copies of each chromosome are separated and moved to opposite sides of the cell via spindle fibres
3)each end now contains a set of identical chromosomes and two new nuclei then form
CYTOKINESIS
the cell membrane pinches inwards to seperate and enclose the two new nuclei,and then pinches off to split the original cell into two new,gentically indentical daughter cells.
GROWTH and why the cell cycle is a cycle
Each of the daughter cells will then grow independently.Following the growth of the daughter cells,the daughter cells will begin replicating their DNA,and cell cycle will continue.
what happens when cells differentiate
cells become specialised to perform a particular job.
-when cells become specialised,they change shape to perform its function.Makes the entire organism more efficient,as life processes are carried out more effectively
sperm cell
-transfers genetic material from male to ovum(egg)
-flagellum-whips from side to side to propel the sperm to the ovum
-lots of mitochondria-reactions of respiration transfer energy from chemical stores so that the flagellum can move
-acrosome-stores digestive enzymes,which break down the outer layers of the ovum to allow the sperm to transfer and incorporate its genetic material
fat cell
-stores fat which can be used as a store of energy,enabling an animal to survive when food is short.Also used in insulation,to from a protective barrier around some organs,such as the heart.However,too much,too much fat in humans is dangerous to health.
-adapted by having a small layer of cytoplasm surrounding a fat reservoir.They can expand up to 1000 times their original size as they fill with fat
red blood cells
-transport oxygen around the blood
-bioconcave discs-increases SA:VOL ratio,speeding up rate of disffusion into cell,and co2 out of cell.
-packed with haemoglobin-this protein binds to oxygen to form oxyhaemogloibin,which is bright red
ciliated cells
cells found in your airways that have goblet cells inbetween them-that produces a sticky mucus.
mucus traps dirt and bacteria and the villi in ciliated cells waft the bacteria towards stomach where it is burned with hydrochloric acid
palisade cell
specialised for the carrying out of photosynthsis.Found in the leaf and are packed with chloroplasts.They also have a regular shape which allows them to be tightly packed in the leaf with other palisade cells.This maximises photosyntheis
what is a stem cell and what is it used for
stem cells are undifferentiated cells.When they divide my mitosis,they form cells which differentiate and become specialised.This means that stem cells can develop into many different tissues and organs and this is useful as our bodies can use this to grow,repair and develop cells
two main types of stem cells
embryonic and adult
embryonic stem cells
divide by mitosis and found in embryos.They produce all the cells an organism needs to survive.This therefore means that embyronic cells can be used to differentiate into all cell types needed.May be seen as unethical as it is literally taking cells out of an embryo
Adult stem cells
found in brain,bone marrow,skin and liver.Has capability of differentiating into some cell types,not as many as embryonic.They act as a repair mechanism for the body as many adult stem cells remain non-dividing for years once an animal has fully grown,which means when activated by a disease or tissue injury,these same cells can start to divide,generating more cells,which can be used to repair bodily damage
what is a meristem
a part of the plant that consists of actively dividing cells forming new tissue
what are stem cells in meristems like
look different to normal plant cells.They are smaller,have thinner walls,smaller vaculoes and have no chloroplasts.When differentiated,they cannot divide as the cell wall is too thick.
what is a surface area to volume ratio
the surface area per unit of volume of an object
why is sa:vol ratio important
if sa:vol ratio is high,this will mean the diffusion distances are small and therefore diffusion rates will be quicker.
-larger the organism,the lower the sa:vol ratio
how have the lungs maximised rate of diffusion
with alveoli which increases surface area of lungs
also good supply of blood which maintains concentration gradient for diffusion by removing oxygen and bringing lots of co2
thin walls in alveoli to give short diffusion distance=easier diffusion
how does small intestine maximise diffusion rate
-digested food molecules are absorbed into the blood from the small intestine.Small intestine contains fingerlike villi that increase the surface area of the intestine wall.Also,microscopic microvill on the villi increase the surface area further.
Why are transport systems needed?
-to transport required systems to where it is needed
main transport systems in animals
-circulatory system.The blood carries materials to where they are required.For example,your liver produces urea when it breaks down excess amino acids.Urea is toxic so the blood transports it to the kidney where it is removed
transport systems in plants
-xylem tubes carry water and mineral ions arond a plant and phloem transport carry sugars and amino acids
What is the circulatory system?
made up of your heart and your blood vessels.
Known as a closed system as blood remains within these structures.
what does blood transport around the body
substances around the body to cells that need them.This includes the oxygen and glucose needed for respiration.Blood also carries away waste products such a carbon dioxide.
what is a double circulatory system
the term to describe how blood flows through the heart twice during each circuit of the body
colours in diagram on circulatory system
red=oxygenated blood(high levels of oxygen)
blue=deoxygenated blood(low levels of oxygen,do not say has none-it still has some oxygen)
NOTE: EVEN THOUGH ON DIAGRAM IT IS BLUE,DEOXYGENOATED BLOOD IRL IS NOT BLUE IT IS RED,JUST BLUE TO DISTINGUISH THE TWO
heart in a cycle
-vena cava is a vein that sends in deoxygenated blood into heart
-goes through right atrium into right ventricle.
-leaves heart through pulmonary artery to lungs
-pulmonary vein sends in oxygenated blood from lungs to heart
-goes through left atrium into left ventricle
-leaves heart through aorta
what does your heart do-basic circulatory system
-pumps blood to your body organs and tissues.Here oxygen and glucose diffuse out of the blood into the cells.CO2 diffuses out of the cells into the blood.In lungs,co2 diffuses out of the blood to be removed from the body and oxygen diffuses in.The blood returns to the heart and cycle starts again
what is a blood vessel
tube-like structures that transport blood around the body.Hollow cavity in the centre is called the lumen and is where the blood actually flows thrugha
arteries
-thick outer wall
-thick layer of muscle and elastic fibres-high pressure
-small lumen
-smooth lining
vein
-fairly thin outer wall
-thin layer of muscle and elastic fibres
-large lumen
-smooth lining
what do valves do
stop backflow(blood flowing the wrong way)
capillaries
-very small lumen
-wall made of single layer cells that are semi-permeable-substances can easily move through them
-link artieris and veins.They form a network so that every cell is close to a capillary.
how does the heart deal with the high pressure waves created when it beats
-the artierial wall is thick and muscular and expands with each contraction then snaps back(called recoil) to push the blood forward
blood pressure in veins
Low-presuure falls as blood passes along the vessels and into the capillaries.One way valves keep the blood flowing back into the heart
What does double circulatory system mean in terms of journeys around the body.
For each journey around the body,The blood is pumped twice.The blood is at a higher pressure than that of a single loop as there is less distance to travel.The high pressure is essential for large organisms such as humans as this means sunstances will be transported quickly around the body
what is heart made of
cardiac muscle-contract without a nerve impluse.Many heart cells contract together to produce a heart beat
red blood cells
Small biconcave cells that have no nucleus and contain haemoglobin. They carry oxygen and fit through the lumen of the capillary one cell at at time
white blood cells
large cells that contain a nucleus and fight disease by making antibodies or by changing shape to engulf microorganisms
plasma
straw-coloured liquid that blood cells float in.Over 90% of plasma is water.Many materials are transported by being dissolved in plasma.These include digested foods(such as acids and glucose),waste(carbon dioxide),hormones,and antibodies.Excess water is taken from the large intestine to the kidneys where it is removed
platelets
tiny structures that help the blood to clot
how are plant transport systems made
by many cells joined end to end
xylem tissue
transports water and mineral ions from the roots to the stem,leaves, and flowers.Water diffuses diffuses into the roots by osmosis,the mineral ions via active transport
phloem tissue
transports dissolved sugars produced during photosynthesis and other soluble food molecules,from the leaves to all other areas of the plant(translocation)
-sugars are taken to meristems where they are needed to create new plant cells and to store tissues in the roots.This provides an energy store
where are phloem and xylem found
close to eachother in a plant.Form a structure known as a vascular bundle.As well as being used for transport,they also provide support
structure of the xylem
-made from dead xylem cells.No cell walls at the ends of these cells.This forms tubes through which the water and dissolved mineral ions can flow.The rest of the xylem cellulose cell wall is thicken to provide support.In trees and woody plants,xylem tissue makes up the bulk of the plant
one way flow
thick walls stiffened with lignin
Structure of the phloem
-mad of living cells.The cell walls of these cells do not completely break down.Instead,sieve plates are formed-small holes in the end wall which allow the dissolved sugars to pass through.
The connection of phloem cells effectively forms a tube which allows dissolved sugars to be transported
2 way flow
How do the vascular bundles provide support
-in the lead they form a network that supports the softer leaf tissue
-in the stem they are located around the outer edge providing the stem with strenth to resist bending in the breeze.
-in the root they are found in the centre,enabling the root to act as an anchor-the root can bend as the plant moves in the wind.
What is transpiration
-plants do not have to have a heart to pump fluids through their transport systems.Water moves through xylem vessels because of transpiration-the loss of water from a plants leaves.The water lost must be replaced,by uptake through the roots
what is the transpiration stream
The constant flow of water from the roots,through the xylem and out of the leaves is called the transpiration stream.
How does water enter the xylem
from soil into root hair cells via osmosis.
Before the water is enetered into a xylem vessel,it must travel from cell to cell until it reaches the centre of the root.Once inside the xylem,the water can be transported throughout the plant.
How is water lost from leaves
stomata on surfaces if leaves allow carbon dioxide to diffuse in photosynthesis.Guard cells allow the stomata to open and close.
-while stomata opens and closes,the water evaporates from cells inside the leaf inot the leaf’s air spaces.This creates a concentration gradient and it diffuses from high to low concentration of water vapour-(leaf into air)
after loss of water from stomata
loss of water reduces pressure of the leaf,meaning water can now move up the tube,from a high pressure to a low pressure(top to bottom)
to prevent uncontrolled water loss
stomata on underside of leaf
cuticle-waxy waterproof layer that is normally thick and shiny and inhibits excess water loss
Why do plants wilt
-When it releases more water than it takes in.The leaves will collapse and droop.This greatly reduces the surface area available for evaporation
-stomata will close,stopping photosyntheisis and prevents water loss.
will eventually die but can survive longer if u decrease light intenisty and temperature
potometer use
to measure how quickly a plant shoot takes up water
factor affecting transpiration
Light intensity
temperature
air movement(wind)
humidity
How does light intensity affect transpiration
more light means more water evaporates meaning the rate of transpiration will increase until all stomata are open(which open depending on the amount of light).
How does temperature affect transpiration
more temperature leads to water evaporating quicker from leaf cells.Diffusion of water vapour out of the leaf becomes more rapid.This increases the rate of transpiration
wind/air movement affect on transpiration
more air means more water molecules are moved,increasing the concentration gradient between the leaf and the air as fewer water molecules are present in the air surrounding hte leaf,compared to inside the leaf.This means that water diffuses more qucikly out the leaf.
how does humidity affect transpiration
higher humidity=more water in the air.If decreased,concentration gradient between leaf and air increases,so water diffuses out quicker,increasing the rate of transpiration.
