transport Flashcards
why do multicellular organisms need transport systems
-direct diffusion from the outer surface would be too slow, substances have to travel large distances to reach every cell
why don’t unicellular organisms need transportation systems
-substances can diffuse directly into and out of cells across the cell membrane
-diffusion rate is quick due to short distances substances have to travel
role of xylem tube
-xylem carries water and mineral salts from the roots up the shoot to the leaves in the transpiration stream
role of phloem tube
-phloem transports sugars like sucrose and amino acids from where they are made in the leaves to other parts of the plants
-movement of food in known as translocation
how is water absorbed by root hair cells
-cells on plant roots have long projections which stick out into the soil
-gives plant big surface area for absorbing water from the soil
-water taken in by osmosis
what does the blood compose of
-plasma
-platelets
-red blood cells
-white blood cells
what does plasma carry
-red and white blood cells and platelets
-digested food products(glucose and amino acids) from the gut to all the body cells
-carbon dioxide from the body cells to the lungs
-urea from the liver to the kidneys
-hormones
-heat energy
function of platelets
-when a blood vessel is damaged, platelets clump together to ‘plug’ the damaged area(blood clotting)
-blood clots stop you losing too much blood and prevent microorganisms from entering the wound
-in a clot, platelets are held together by a mesh of a protein called fibrin
red blood cells’ role
transports oxygen form the lungs to all the cells in the body
adaptations of red blood cells
-small and biconcave shape to give a large surface area for absorbing and releasing oxygen
-contain haemoglobin(gives blood its colour), contains iron. In the lungs haemoglobin reacts with oxygen to become oxyhaemoglobin. In body tissues, reverse reaction happens, releasing oxygen to the cells
-red blood cells have no nucleus, freeing up space for more haemoglobin to carry more oxygen
pathogens
-microorganisms that cause disease
-will reproduce rapidly in your body unless they are destroyed by your immune system
-phagocytes
-detect things that are ‘foreign’ to your body
-encircle pathogens by the cell membrane extensions (pseudopodia), engulfing pathogens and releasing digestive enzymes onto the engulfed pathogens
-non-specific
lymphocytes
-when lymphocytes come across a foreign antigen, they will start to produce proteins called antibodies
-antibodies lock onto the invading pathogens and mark them out for destruction by other white blood cells
-antibodies produced are specific to that type of antigen
-antibodies are produced rapidly and flow around the body to mark all similar pathogens
memory cells
-they are also produced in response to a foreign antigen
-these remain in the body and remember a specific antigen
-can reproduce very fast if the same antigen enters the body again
how do vaccinations work
-lymphocytes can take a while to produce the antibodies to deal with it
-vaccinations help to avoid getting very ill or dying
-vaccination involves injecting dead or inactive pathogens into the body
-these carry antigens, triggering an immune response
-lymphocytes produce antibodies to attack them
-memory cells will also be produced and remain in the blood
