Exchange of materials Flashcards
What is active transport?
movement of particles from an area of low concentration to an area of high concentration, against a concentration gradient, using energy released from mitochondria in respiration
What must cells be able to do?
transport substances in and out
Give examples of active transport
Ions into root hair cells
glucose into kidney tubules
What is osmosis?
movement of water molecules from a dilute solution to a more concentrated solution across a semi permeable membrane
Why is osmosis across a semi permeable membrane?
on small molecules can fit through pores
When do molecules stop moving to high concentrated solution?
when equilibrium is reached, resulting in no overall net movement
What happens when animal cell is placed in dilute solution?
water molecules move into animal cell and membrane can’t stand those levels of high pressure so it bursts
What happens when a plant cell is placed in a dilute solution?
cell swells and cytoplasm and membrane push against cell wall. Cell wall resists further expansion and become turgid.
What happens when an animal cell is placed in concentrated solution?
Water moves out of animal cell, causing it to shrivel up
What happens when a plant cell is placed in a concentrated solution?
membrane and cytoplasm shrink away from cell wall, causing it to become flaccid.
What must the concentration of water outside cells be?
constant
What happens during exercise?
Reduction of glucose which is needed for respiration to provide energy
Sweat - lose water and mineral ions (electrolytes) so cells work inefficiently
What do sports drinks do?
Replace water
Replace electrolytes
Replace sugar
What factors make exchange surfaces more effective?
Large surface area
thin (short diffusion path)
efficient blood supply - extensive capillary network in exchange organs
ventilated
How are lungs adapted to exchange O2 and CO2?
Alveoli: good blood supply large surface area thin - O2 can diffuse in quicker and CO2 out Ventilated - breathe in and out
How are small intestines adapted to exchange substances?
Inside surface: Villi and microvilli which increase surface area
efficient blood supply - dense network of capillaries
thin
many mitochondria - provide energy for active transport
What happens when we breathe in?
intercostal muscles contract
ribcage moves up and out
diaphragm contracts, pulling downwards
lung volume increases and air pressure inside decreases
What happens when we breathe out?
Intercostal muscles relax Ribcage moves down and in diaphragm relaxes, moving up lung volume decreased and air pressure inside increases air pushed out of lungs
What is a negative pressure aid to breathing and how does it work?
Iron lung:
Person aced in giant metal container, sealed tightly at neck so no air can leak
Air pumped out of iron chamber, lowering pressure
higher air pressure outside so air drawn into lungs
Reverse this so that air rushes back in and lungs deflate and push air back out again
Give positive evaluation points of iron lung
keeps patient alive
breathes for patient
give negative evaluation points of iron lung
Patient has to lie inside large machine
Doesn’t work as well as positive pressure breathing system
What is a positive pressure system and how does it work?
Large inflatable bag controlled by doctor
controls amount of air that goes in through mask
con be controlled by machine which regulates breathing
What are the advantages of positive pressure breathing systems?
Quick and easy to use
Machine based systems can be portable and used for long periods
What are the disadvantages of positive pressure breathing systems?
They are only temporary
How does CO2 get into leaf? What is it required for?
via diffusion.
Required for photosynthesis and is waste product of respiration
How to O2 exit leaf?
Via diffusion
required for respiration
waste product of photosynthesis
What enter via roots?
water and mineral ions
What is the function of root hair cells?
increase surface area for water and mineral ions
How are leaves adapted to exchange materials?
flat with internal air spaces
thin so short diffusion path
stomata which are controlled by guard cells and open and close to allow O2 and CO2 out and in
spongy Mesophyll which increases surface area
what is lost through stomata and why?
water vapour because of evaporation in leaves
When do stomata close and why?
if plants lose water faster than its replaced by roots then stomata close to prevent wilting
When is evaporation more rapid?
hot, dry and windy conditions
