2 Transport Flashcards
What organism can rely on diffusion for movement of substances in and out of cells?
simple unicellular organism
large surface are to volume ratio so short diffusion distance
Why do multicellular organisms need a transport system?
have small surface area to volume ratio
transport system needed to deliver nutrients, oxygen and other substances to all body cells and take away waste products
simple diffusion too slow
What does the phloem transport?
sucrose (converted from sugar made in photosynthesis) and amino acids - from leaves (where they’re made) to the growing points (e.g. tips of the shoot and flowers) or storage areas (roots or bulbs)
What is the phloem made up of?
tubes formed by living cells arranged end to end
Moving sucrose and amino acids around the plant requires…
energy
this is called translocation
What does the xylem do?
transports water (and minerals) to the leaf
How do the xylem transport water and mineral ions from root to leaf?
Water molecules move through the plant upwards in a transpiration stream
What is the xylem made up of?
thick walled dead cells containing no cytoplasm
cell walls contain lignin - waterproof
What are nitrate ions needed for in plants?
to make amino acids and proteins
What are magnesium ions needed for in plants?
to make chlorophyll
PAPER 2 How is water absorbed by root hair cells?
Root hair cells are elongated cells which give the plants a big surface area for absorbing water from the soil.
Water is taken in via osmosis
PAPER 2 What is transpiration?
The evaporation of water from the stomata
PAPER 2 What factors affect the rate of transpiration?
Light intensity
Temperature
Wind speed
Humidity
PAPER 2 How does light intensity affect the rate of transpiration?
brighter light, greater transpiration rate
stomata close as it gets darker as photosynthesis can’t happen. When stomata are closed, little water can escape
PAPER 2 How does temperature affect the rate of transpiration?
warmer = faster transpiration
particles have more energy to evaporate and diffuse out of the stomata
PAPER 2 How does wind speed affect the rate of transpiration?
higher wind speed around leaf, greater transpiration rate
water vapour is swept away, maintaining a low concentration of water in air around leaf. Diffusion happens quickly, from area of high to low concentration
PAPER 2 How does humidity affect the rate of transpiration?
drier air, faster transpiration
if air is humid, there is lots of water surrounding plant so little difference between inside and outside of plant. Diffusion happens slowly/not at all
PAPER 2 Use CORMS to describe an investigation of the role of environmental factors in determining the rate of transpiration from a leafy shoot.
Potometers measure the uptake of water and estimate transpiration
Change - conditions ( vaseline, no vaseline, wind, no wind )
Organism - plant (cut shoot at slant to increase SA and underwater to prevent air from entering xylem )
Repeat - 3 times
Measure - distance bubble moves
Same - species (laurel)
What is the composition of blood?
Plasma
Red blood cells
Platelets
White blood cells
What is the plasma?
straw coloured liquid
transports blood cells and other substances
e.g. dissolved nutrients such as glucose and amino acids; dissolved waste products including urea and carbon dioxide; hormones; proteins; heat energy
What are red blood cells?
transport oxygen, bound to haemoglobin