B2 Cell Transport Flashcards
What is the meaning of ‘diffusion’?
The spreading out of particles, resulting in a net movement from an area of higher concentration to an area of lower concentration.
What is the definition of the word ‘osmosis’?
The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
What is the definition of the phrase ‘active transport’?
The movement of particles from a more dilute solution to a more concentrated solution using energy from respiration.
What is the movement of particles like in diffusion?
Particles move down the concentration gradient - from an area of high concentration to an area of low concentration.
What is the movement of particles like in osmosis?
Water moves from an area of lower solute concentration to an area of higher solute concentration.
What is the movement of particles like in active transport?
Particles move against the concentration gradient - from an area of low concentration to an area of high concentration.
Is energy required for diffusion?
No, its a passive process
Does osmosis require energy?
Nope, it’s a passive process.
Does active transport require energy?
Yes- it uses the energy released by respiration.
How is diffusion used in human small intestines?
The nutrients in the small intestine diffuse into the capillaries through the villi.
How is diffusion used in human lungs?
Oxygen diffuses from the air in the alveoli into the blood in the capillaries. Carbon dioxide diffuses from the blood in the capillaries into the air in the alveoli.
How is diffusion used in human kidneys?
Urea diffuses from cells into the blood for excretion in the kidney.
How is diffusion used in fish?
•oxygen from water passing over the gills diffuses into the blood in the gill filaments.
•carbon dioxide diffuses from the blood in the gill filaments into the water.
How is diffusion used in plants?
•carbon dioxide used for photosynthesis diffuses into leaves through the stomata.
•oxygen produced during photosynthesis diffuses out of the leaves through the stomata.
How is osmosis used in plants?
Water moves by osmosis from a dilute solution in the soil to a concentrated solution in the root hair cell.
How is active transport used in humans?
It allows sugar molecules to be absorbed from the small intestine when sugar concentration is higher in the blood than in the small intestine.
How is active transport used in plants?
It’s used to absorb mineral ions into the root hair cells from more dilute solutions in the soil.
What factors affect the rate of diffusion?
• difference in concentration
•temperature
•surface area of the membrane
How does difference in concentration affect the rate of diffusion?
The steeper the concentration gradient, the faster the rate of diffusion.
How does temperature affect the rate of diffusion?
The higher the temperature, the faster the rate of diffusion.
How does surface area of the membrane affect the rate of diffusion?
The larger the membrane surface area, the faster the rate of diffusion.
Do single celled organisms have a small surface area-to-volume ratio?
No! They have a large surface area-to-volume ratio.
Why do single celled organisms have large surface area-to-volume ratios?
So enough molecules can be transported across their cell membranes to meet their needs.
Do multicellular organisms have small surface area-to-volume ratios?
Yes, they do!
Why do multicellular organisms have a small area-to-volume ratio?
They have specialised organ systems and cells to allow enough molecules to be transported into and out of their cells
What factors make exchange surfaces work most efficiently?
•large surface area
•thin membrane
•good blood supply
Why do you have villi in the small intestine?
To absorb nutrients.
What adaptations do villi in the small intestine have to make them more efficient?
•network of capillaries
•large surface area due to folding
•thin wall (one cell thick)
•good blood supply
Why is there alveoli in the lungs?
For gas exchange.
What adaptations do alveoli in the lungs have to be more efficient?
•network of capillaries provides a good blood supply
•has a large surface area
•is moist
•is one cell thick (short diffusion pathway)
What is the purpose of fish gills?
For gas exchange.
What adaptations do fish gills have to be more efficient?
•large surface area to increase diffusion
•a network of capillaries (good blood supply)
What is the purpose of root hair cells?
To uptake water and minerals.
What are the adaptations of root hair cells to make them more efficient?
•lots of mitochondria (to take in mineral ions by active transport)
•large surface area (helps efficient absorption of water and mineral ions)
