Unit 4.1.3 Transport In Cells Flashcards
what is being described?
the random movement of particles from an area of high concentration to an area of low concentration (down a concentration gradient) until there is no net movement (particles are evenly distributed/equilbrium reached)
diffusion
A concentration gradient is
the difference in concentration between one area and another - the bigger the difference the bigger the gradient
What factors affect rate of diffusion
temperature, concentration gradient and surface area
Give an example of diffusion in real life
synapses, leaves, gut, lungs, roots,
What part of a cell do molecules have to cross in diffusion?
cell membrane
In cells what diffuses?
oxygen and glucose diffuses IN and carbon dioxide diffuses OUT
What is an alveoli?
air sac found in the lungs - this is where diffusion of gases occurs
How are exchange surfaces adapted for exchange?
large surface area, moist, extensive blood supply, thin
If a cube has a length of 2 cm calculate its surface area, volume and surface area: volume ratio
surface area: 24
volume: 8
surface area: volume ratio 3:1
Osmosis is
the movement of WATER particles from an area of low solute concentration to an area of high solute concentration across a selectively permeable membrane
Osmosis occurs in the
roots of a plant
When carrying out a practical to determine the solute concentration inside a potato, why do you calculate % change in mass?
because the mass of potatoes can vary
When carrying out a practical to determine the solute concentration inside a potato, why do you blot the potatoes dry?
to remove any excess water as this may affect the final mass
Active transport is
the movement of particles from an area of low concentration to an area of high concentration (up or against a concentration gradient). Energy is required which comes from respiration.
Active transport in plants occurs in
the roots for the absorption of mineral ions
Active transport in animals occurs in
the small intestine (gut) for the absorption of glucose/sugar
What type of organism can rely of simple diffusion to meet its metabolic needs?
A singled cells organisms
Feature of single celled organisms is
it has a large surface area to volume ratio
Large multicellular organisms need exchange surfaces and a transport system because
they have a small surface area to volume ratio and CAN NOT obtain the materials they need by simple diffusion
plants require mineral ions for
healthy growth
Plants obtain mineral ions from the soil by
active transport
Structures in the small intestine are called
villi
These cells are adapted to absorb water and minerals from the soil
root hair cells
root hair cells absorb mineral ions by what process?
active transport
water is absorbed in the roots by what process?
osmosis
Active transport is also used in humans, name the location
Gut - small intestine
What can be said about the SA:volume ratio of a single celled organism?
it is large
What can be said about the SA:volume ratio of a multicellular organism
it is small
Exchange surfaces are adapted for exchange - how?
large SA
thin
extensive blood supply
exchange surfaces include
lung(alveoli), small intestine (villi), roots, leaf
In the alveoli what is exchanged?
oxygen IN
carbon dioxide OUT
In the small intestine what is exchanged?
glucose into blood
amino acids into blood
fatty acids and glycerol into blood
What are the lungs composed of?
alveoli
How is a leaf adapted for exchange?
thin, many stomata, large surface area, air spaces inside leaf
At the leaf surface what is exchanged during the day?
carbon dioxide in
oxygen out
At night what is exchanged at the leaf surface?
water out
carbon dioxide out
oxygen in
What does a plant use carbon dioxide for?
photosynthesis
When does photosynthesis take place?
during the day
During the day what opens on the leaf to allow for exchange to occur?
stomata
At night what happens to the stomata?
they close
What other molecule diffuses out of the leaf?
water
What is the exchange surface of fish called?
gills
How are the gills of a fish adapted for exchange?
large SA, thin, extensive blood supply = maximises diffusion!
