transport Flashcards
why can unicellular organisms rely on diffusion for movement of substances?
they have a large surface area to volume ratio so nutrients and other substances can pass into their cell quickly and easily.
why do large multicellular organisms need transport systems?
they have a small surface area to volume ratio and therefore cannot rely on diffusion of substances as this would take too long and would not provide enough of the necessary nutrients needed.
what does the phloem transport and how?
the phloem moves sucrose and amino acids via translocation (in both directions)
what does the phloem consist of?
living cells arranged end to end.
the phloem enables movements between —– and —–.
sources (where substances are made or absorbed) and sinks (where substances are used or stored)
does translocation require energy?
yes, companion cells provide this energy.
state the function of the sieve plates in the phloem
allow for continuous movement of organic substances up and down the phloem
what does the xylem transport and how?
water and mineral ions via the transpiration stream (upwards only)
what does the xylem consist of?
elongated dead cells (no cytoplasm, impermeable to water, cell walls contain lignin) arranged end to end to form vessels
how are minerals and water absorbed by the root hair cells?
minerals are absorbed by active transport, water is absorbed by osmosis.
give two adaptations of root hair cells
large SA, contain many mitochondria.
what is transpiration?
the evaporation of water from the surface of a plant’s leaves through the stomata.
state and explain the effect of increasing light intensity on transpiration.
as light intensity increases, transpiration increases as the stomata open wider to allow more carbon dioxide into the leaf for photosynthesis.
describe the pathway of water from the soil to the leaves
soil -> root hair cells -> root cortex cells-> xylem -> leaf
describe the composition of blood
red blood cells, white blood cells, platelets and plasma
what is the role of the plasma?
transporting carbon dioxide, digested food, urea, hormones and heat energy
give 4 adaptations of red blood cells
- biconcave
- large surface area
- no nucleus
- haemoglobin
what is the purpose of phagocytes?
phagocytosis, ingesting pathogens.
what is the purpose of lymphocytes?
releasing antibodies specific to a pathogen.
what do antibodies do?
they attach to a pathogen’s antigens
- stick the pathogens together in clumps
- label the pathogen so it can be found by phagocytes
- neutralise toxins produced by the pathogen
how do vaccinations work?
they inject small doses of an inactive pathogen, enabling the manufacturing of memory cells, which enable future antibody production to the pathogen to occur sooner, faster and in greater quantity.
what is the function of platelets?
platelets are involved in blood clotting to prevent blood loss and entry of micro organisms.
describe the actions of platelets
they cause a rapid enzyme catalysed response at the site of a damaged vessel
- fibrinogen -> fibrin, creating a protein mesh.
Definition of a pathogen
A disease causing cell. Can be fungi, bacteria, protoctist and viruses.
3 differences between structures of artistries and veins
- Arteries have thicker, more elastic walls
- Arteries do not have valves
- Arteries have smaller lumens.
Function of capillaries.
To take oxygen and nutrients to cells in organs and muscles as well as to take waste products away.
Adaptations of capillaries.
- small
- one cell thick walls
Explain why heart rate increases during exercise
- an increased amount of energy is needed for muscles to contract
- more blood carrying oxygen and glucose needs to be pumped by the heart to the muscles for aerobic respiration
- heart rate increases
Explain what happens when someone has Coronary Heart Disease.
The coronary artery, which supplies blood to the heart for aerobic respiration becomes blocked (by a buildup of fat) and so the heart may run short of O2 and not be able to contract.
Factors to decrease risk of CHD:
- regular exercise
- eating fewer fatty foods
- smoking (increases blood pressure)
- hereditary
- high cholesterol levels
Lungs to heart
Pulmonary vein
Heart to lungs
Pulmonary artery
Heart to liver
Hepatic artery
Liver to heart
Hepatic vein
Heart to kidney
Renal artery
Kidney to heart
Renal vein
Main artery away from the heart
Aorta
Main artery into the heart
Vena cava
Give 2 adaptations of an artery
Strong and thick muscular walls, elastic fibres
Give 3 adaptations of a vein
Valves, thin walls, elastic walls
