1.3 Transport in cells Flashcards
1.3.1 Diffusion
What is diffusion
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration.
1.3.1 Diffusion
Examples of where diffusion occurs in the body
- oxygen and carbon dioxide in gas exchange
- urea (waste product) diffused out of kidney
1.3.1 Diffusion
Explain how different factors affect the rate of diffusion.
- Difference in concentration: the greater the difference, the faster the rate of diffusion (steeper)
- temperature: the higher the temperature, the more kinetic energy, moves faster = quicker diffusion rate
- surface area of membrane: greater SA = greater diffusion rate; more entry/exit points for particles to cross
1.3.1 Diffusion
Surface area:Volume
calculation
Surface area: 6(l x w)
Volume: l x w x d
6(l x w) : l x w x d
1.3.1 Diffusion
Adaptations in small intestines
- internal surface have millions of villi
- villi increase the surface area
- villi have a very rich blood supply
- maintains the concentration gradient
- membranes of villi are very thin to allow for short diffusion distance
1.3.1 Diffusion
Adaptations of the lungs
- contains alveoli
- increases surface area
- very good/rich blood supply
- maintains concentration gradient
- membranes of alveoli are very thin, to allow for short diffusion distance
1.3.1 Diffusion
Adaptations of gilld in fish
- each gill has thin plates called gill filaments, water with low oxygen flows over them
- increases surface area
- covered with lamella: increases the surface area more
- lamella: have a very good blood supply
- maintains the concentration gradient as water flows in the opposite direction
- membranes of the lamellae are very thin, to allow for short diffusion distance
1.3.1 Diffusion
Adaptations of the roots
- root surface is covered in millions of root hair cells
- increases the surface area
- present on the mature parts of the roots
- absorbs water and minerals from the soil
1.3.1 Diffusion
Adaptations of the leave
- large SA to absorb more light
- thin, short distance for carbon dioxide to diffuse into leaf cells
- chlorophyll absorbs sunlight for photosynthesis
- xylem and phloem to support the leaf and transport water and glucose
- stomata at the bottom to allow gases to diffuse in and out of leaf
1.3.2 Osmosis
What is osmosis
The movement of water from a dilte solution to a concentrated solution through a partially permeable membrane
low to high conc
1.3.2 Osmosis
Factors that affect osmosis
- Difference in concentration: the greater the difference, the faster the rate of diffusion (steeper)
- temperature: the higher the temperature, the more kinetic energy, moves faster = quicker diffusion rate
1.3.2 Osmosis
Key words in osmosis
Hypertonic: more concentrated solution, than in cells. Cell loses water, shrinks
Isotonic: same concentration of solution, as the cell solution. no change to the cell
Hypotonic: more dilute solution, than in cells. cell absorbs water, expands.
Hypertonic: exits
Hypotonic: absorbs
1.3.3 Active transport
What is active transport
Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient)
Requires energy from respiration
1.3.3 Active transport
Example of active transport in plants
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.
1.3.3 Active transport
Example of active transport in animals
It also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration.
Sugar molecules are used for cell respiration.
