❤️🔥2- transport Flashcards
(89 cards)
where does the exchange of substances occur
across the cell membrane
unicellular organisms have
very large surface areas in comparison to their volumes this means that the distance between the surface of the organism to its centre is very small
unicellular organisms do not need to have
specialist exchange surfaces or transports systems as processes such as diffusion, osmosis and active transport through the cell membrane occur at a sufficient rate to meet the organisms needs
large multicellular organisms like humans have
relatively small surface areas in comparison to their volumes so the distance between the surface of the organism to its centre is relatively long
exchange surfaces in animals include
the lungs and alveoli for gas exchange, the small intestine and villi for absorption of digested foods
transport systems in animals include
the blood and circulatory systems carries the necessary substances around the body
exchange surfaces in plants include
roots and root hairs where mineral ions and water are absorbed, the leaves for gas exchange
transports systems in plants include
the xylem moves water and mineral ions from roots to shoots, the phloem moves sugars and amino acids to where they are needed in the plant
the roots, stem and leaves form a
plant organ system for the transport of substances around the plant
plants also possess
two specialist transport vessels called the xylem and phloem
the xylem and phloem are arranged
throughout the root, stem and leaves in groups called vascular bundles
xylem vessels transport
water and minerals from the roots to the stem and leaves
xylem key structural features
-it is composed of dead cells which form hollow tubes, xylem cells are strengthened by lignin and so are adapted for the transport of water in the transpiration system
phloem vessels transport
food materials (mainly sucrose and amino acids) made by the plant from photosynthesising leaves to non photosynthesising regions in the roots and stem, this means that they can be in any direction around the plant
phloem key structural features
the cells are living cells and not hollow, substances move from cell to cell through pores in the end walls of each cell
blood consists of
red blood cells, white blood cells, platelets and plasma
over half the volume of blood consists of
plasma
the majority of the other half of blood consists of
red blood cells
a small fraction of blood consists of
white blood cells and platelets
red blood cells
biconcave discs containing no nucleus but plenty of the protein haemoglobin
white blood cells
large cells containing a big nucleus, different types have slightly different structures and functions
platelets
fragments of cells
plasma
straw coloured liquid
red blood cells are
specialised cells which carry oxygen to respiring cells