B2

transport

unicellular transport

relies on diffusion

• O2/glucose in, CO2/H2O out

multicellular transport

too many cells for diffusion to supply them all in time

• exchange surfaces allow substances in/out of transport system

surface area to volume ratio

the larger an organism, the smaller a ratio

• as there isn’t enough exchange surface for diffusion, the cells in the center don’t get the resources they need in time.

SA : V ratio calculation

surface area / volume : 1

role of the alveoli

to support gas exchange between alveoli and capillaries

adaptations of the alveoli

• circular shape which allows for larger surface area for exchange

• high concentration of oxygen vs low concentration in the blood stream

• thin membrane(1 cell think) to shorten diffusion distance

• moist to dissolve gases & avoid air bubbles in blood stream

• network of capillaries around alveoli to maximize gas exchange
  

adaptations of the villi

• thin 1 cell thick walls in a single flat layer for short diffusion distance

• finger-like projections to increase surface area & allow for regular stacking

• large quantity of villi in a very long intestine

• large quantity of blood in vessels for nutrients to diffuse into

diffusion

the random movement of particles from a high concentration to a lower concentration

• moves down the concentration gradient as it is passive

concentration gradient

difference in concentration between 2 areas

• a steeper gradient means faster diffusion

factors that may affect gradient of diffusion

• concentration gradient

• temperature

• diffusion distance

active transport

the movement of molecules from an area of low concentration to an area of higher concentration

• goes up the concentration gradient(natural flow) as it goes against it

carrier proteins

required to “scoop” the particle and pushes it to the other side

• this is because energy is required to move the particles in active transport(atp)

carrier protein image

osmosis

the total movement of water molecules from an area of high water potential to an area of low water potential.

• MUST go through a partially permeable membrane

water potential

the ability of water to freely move, measured in Psi (Ψ)

how water potential works

as particles move from a higher concentration to a lower concentration, it eventually leads to equilibrium on both sides of the permeable membrane

water potential in practice

RBC placed in distilled water

RBC placed in concentration solution(salt/sugar)

double circulatory system

a system of blood circulation where blood passes through the heart twice in one complete circuit of the body.

role of the circulatory system

• the heart pumps oxygenated blood to cells deliver O2 and glucose

• the heart pumps deoxygenated blood to lungs to remove CO2 and H2O

arteries

carries blood away from the heart

• thick muscle walls to withstand high pressure of blood

• small lumen(hole) to maintain pressure(smaller area)

• high pressure from heart compressions

veins

carry blood to the heart

• thin muscle walls as blood is at low pressure

• valves to prevent backflow of blood

• large lumen to reduce resistance to flow

capillaries

connects arteries & veins

• walls are 1 cell thick(short diffusion distance)

• where gases are exchanged with cells

• pressure from heart contractions force capillary substances out

Pulmonary

anything related to the lungs

root hair cells

adaptations of a root hair cell

• long & thin protrusions to fit between soil particles

• large surface area for uptake of minerals & water

• lots of mitochondria(atp) for active transport

• vacuole containing sap to lower water potential 

how a root hair cell works

active transport of mineral ions requires energy as it is active transport (less mineral on outside than inside)

• water potential is lowered on the inside so that water can go in through osmosis

xylem

transports water & minerals from roots to the rest of the plant

phloem

transports dissolved sugars(assimilates) from photosynthesis to the rest of the plant

• aka translocation

vascular bundle

Bundle of xylem & phloem within the plant

• different distribution in roots & system

• supports the plant in the stem

• anchors the plant in the roots

adaptations of xylem

• made of dead cells

• flows upward

• impermeable cell wall

• thick cell wall made of lignin

• provides support

adaptations of phloem

• made of living cells

• flow is up & down

• sieve plates present at the end of cells to allow dissolved sugars to pass through

• thin cell wall made of cellulose

transport system cross section

• phloem is packed in regular shape(more dense)

• xylem is less dense, usually darker in color on test papers