Cell Transport Flashcards
What is diffusion?
The movement of particles down a concentration gradient (high -> low concentration)
Is diffusion a passive process?
Yes - energy not required
Name 3 examples of diffusion in animals or plants.
- Humans: urea diffuses from cells into the blood for excretion
- Fish: oxygen from water passing over gills diffuses into gill filaments
- Plants: carbon dioxide used in photosynthesis diffuses into leaves via the stomata
Etc…
What is osmosis?
The movement of water particles from a dilute to a concentrated solution through a semi-permeable membrane (dilute -> concentrated)
Is osmosis a passive process?
Yes - no energy required
Name an example of osmosis in plants.
Water moves by osmosis from a dilute solution in the soil to a concentrated solution in the root hair cell
What is active transport?
The movement of particles against a concentration gradient using energy from respiration (low -> high concentration)
Is active transport a passive process?
No - energy is required
Name an example of active transport in plants or animals.
- Humans: sugar molecules absorbed from small intestine when sugar concentration is too high
- Active transport used to absorb mineral ions into root hair cells from more dilute solutions in soil
Etc…
Name 3 factors that affect the rate of diffusion.
- Difference in concentration
- Temperature
- Surface area of membrane
How does the difference in concentration affect rate of diffusion?
The steeper the concentration gradient (bigger the difference in concentration) -> the faster the rate of diffusion.
How does the temperature affect rate of diffusion?
The higher the temperature, the faster the rate of diffusion.
How does the the surface area of the membrane affect rate of diffusion?
The larger the surface area, the faster the rate of diffusion
What is the surface area:volume ratio like in single-celled organisms?
Large SA:V ratio
What is the surface area:volume ratio like in multicellular organisms?
Small SA:V ratio (so need specialised organ systems and cells)
Name 2 ways villi are adapted to optomise nutrient absorption.
- Large surface area due to folding
- Thin cell wall (one cell thick)
- Good blood supply
Etc
Name 2 ways alveoli are adapted to optimise gas exchange.
- Network of capillaries -> good blood supply
- Microvilli -> large surface area
- One cell thick -> small diffusion distance
Name 2 ways fish gills are adapted to optimise gas exchange.
- Large surface area for increased diffusion
- Network of capillaries -> good blood supply
Name 2 ways root hair cells are adapted to optimise water and mineral uptake.
- Lots of mitochondria -> take in mineral ions via active transport
- Large surface area -> increases SA:V ratio
