Transport In Cells Flashcards
What is diffusion
the spreading out of particles from an area of higher concentration to an area of lower concentration
what molecules cannot fit across a cell membrane
starch and proteins
how does concentration effect the rate of diffusion
the bigger the concentration gradient the faster the rate of diffusion.
how does temperature effect the rate of diffusion
when the temperature is higher the particles have more energy so move around faster so rate is higher
how does surface area effect the rate of diffusion
the larger the surface area the faster the rate because more particles can pass through at once
what is osmosis
the movement of water particles across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
what is active transport
the movement of particles against a concentration gradient using energy from respiration
how do plants use active transport
root hair cells are on roots of plants. they absorb mineral ions using active transport
how do humans use active transport
in the gut wall to absorb nutrients when the concentration in the blood is higher
give an example of gas exchange in humans
oxygen and carbon dioxide is transferred between cells and the environment
how is urea diffused
diffuses from cells into the blood for removal in the kidneys
why are exchange surfaces needed
multicellular organisms have a lower surface area to volume ratio. so not enough substances can diffuse from outside to supply the entire volume
what are 3 ways exchange surfaces are adapted to maximize effectiveness
thin membrane so substsnces have a short way to travel
large surface area so lots can move at once
lots of blood vessels so it can be gotten into and out of blood quickly
where does gas exchange happen in the lungs
alveoli
what are the tubes called that connect to the alveoli
bronchioles
what are 4 adaptations of alveoli
large surface area
moist for absorbing gasses
good blood supply
very thin walls
the inside of the small intestine is covered in millions of tiny projections called what
villi
why are villi good at their job
increase the surface area so food can be absorbed quicker
good blood supply to assist absorption
a single layer of surface cells
what does carbon dioxide enter a leaf through
stomata
how do air spaces in leaves help carbon dioxide absorption
more cell walls are available for diffusion
how do fish absorb oxygen
water enter through a fishes mouth and passes through the gills. as this happens oxygen diffuses from the water into the blood.
how are gills adapted
each gill is made up thin plates called gill filaments
the gill filaments are covered in lots of tiny structures called lamellae
lamellae have lots of blood capillaries and a thin surface layer of cells
how is a concentration gradient maintained in gills
the blood flows through the lamellae in one direction and the water flows over it in another
