plants, blood and blood vessels Flashcards
transpiration
water moves from the roots to the leaves in the xylem. water moves in one direction only (up) and evaporates out of the stomata
translocation
sucrose, glucose and starch move into the phloem. the movement of substances is either up or down.
explain 3 adaptions of the xylem
dead cells with no walls between them to create an empty tube.
thick side wall to make the xylem rigid.
lignin rings along with the thick side wall means that the xylem does not collapse or burst under water pressure.
explain 4 key adaptions of the phloem
sieve tube transports sucrose made by photosynthesis,
central channel is connected by holes to the next cell
companion cells actively pumps sucrose in and out of sieve cells.
sucrose being pumped into sieve cells at the leaf increases the pressure, causing the sucrose to move up and down the plant.
artery (BV)
thin lumen, thick elastic walls, under high pressure, carry blood away from the heart
veins (BV)
thick and wide lumen, valves that prevent back flow, under low pressure, brings blood back to the heart. large space for the blood to travel back.
capillaries (BV)
one cell thick walls which create a short diffusion distance. allows substances to diffuse rapidly through the blood and body cells
as blood passes through substances like glucose and oxygen diffuse out of blood into cells.
carbon dioxide diffuses from cells into blood.
plasma (B)
liquid part of blood. carries blood cells through blood vessels. contains dissolved substances such as carbon dioxide and glucose.
platelets (B)
dead cells that form scabs (clotting) which stops excessive bleeding and prevents pathogens from entering. no nucleus.
lymphocytes/ white blood cells (B)
fight disease, antigens, pathogens, antitoxins and phagocytes by engulfing pathogens. have a nucleus.
erythrocytes/red blood cells (B)
carry oxygen, haemoglobin, no nucleus and have a biconcave shape.
3 adaptions of the alveoli
millions of tiny air sacs/ alveoli create large surface area, thin walls that are one cell thick for shorter diffusion distances. ventilation allows continuous blood flow which creates high concentrations for maximum diffusion.
