B1b- cell transport Flashcards
substances may move into and out of cells across the cell membranes via…
diffusion
what is diffusion?
diffusion is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.
what are some of the substances transported in and out of cells by diffusion in gas exchange?
oxygen and carbon dioxide
what are some of the substances transported in and out of cells by diffusion in waste product?
urea from cells into the blood plasma for excretion in the kidney.
what are factors that affect the rate of diffusion?
- the difference in concentrations (concentration gradient)
- the temperature
- the surface area of the membrane.
water may move across cell membranes via…
osmosis
what is osmosis?
osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
what are the units for osmosis?
g/min
what is active transport?
Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.
what does active transport allow mineral ions to do?
Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth.
what does active transport allow sugar molecules to do?
Active transport allows sugar molecules to be absorbed from lower concentrations in the small intestine into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration.
what is the difference between osmosis, active transport and diffusion?
Diffusion is the movement of particles from a HIGH to LOWER concentration.
Osmosis is the diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane
Active transport moves substances from a more DILUTE solution to a more CONCENTRATED
why does a single-celled organism has a relatively large surface area to volume ratio
It allows sufficient transport of molecules into and out of the cell to meet the needs of the organism.
how are exchange surfaces areas adapted for exchanging materials
they are thin- so substances only have a short distance to diffuse
they have a large surface area- so lots of substances can diffuse at once
they maintain a concentration gradient (e.g by having a good blood supply)- so substances keep diffusing in the right direction
they are often moist
