Transport Flashcards
What is the definition of diffusion?
The spreading out of particles of any substance in a solution or of a gas resulting in a net movement from high to low concentration.
What substances are transported in and out of cells by diffusion?
Oxygen, carbon dioxide and urea.
What factors affect the rate of diffusion?
Concentration gradient, temperature and surface area.
Which organs have adapted for diffusion?
The lungs, gills, intestines and roots in plants.
How have organs adapted for diffusion?
Large surface area. Thin membranes to provide short diffusion pathway. Efficient blood supply in animals. Well ventilated in plants.
What is the definition of osmosis?
The movement of water across a partially permeable membrane from a dilute to concentrated solution.
When can osmosis occur?
When tissue is submerged in salty water, tissue mass decreases because water diffuses from higher concentrations in the cell to lower concentrations outside the cell through the semi-permeable membrane.
What is the definition of active transport?
The movement of substances from low to high concentration using energy from respiration.
Why is active transport necessary?
To maintain the right concentrations of molecules in cells.
What is xylem?
The process of transportation of water, salts and minerals from the roots to the rest of the plant.
What is phloem?
The transportation of minerals throughout the entire plant from the leaves during photosynthesis.
What is transpiration?
It is the evaporation and movement of water away from the plant’s leaves from the inside of the plant occurring as water diffuses through the plant from the roots and evaporates from the leaves through the stomata openings.
What is the process of investigating osmosis in plant tissue? (RP)
- Peel potato.
- Use cork baller to produce 3 cylinders of potato.
- Use a scalpel to trim cylinders to the same length (3cm).
- Measure and weigh mass (using a balance) of each cylinder.
- Place each cylinder into a test tube.
- Add 10cm³ of 1 molar sugar solution to test tube 1, 0.5 molar to test tube 2, distilled water in test tube 3.
- Leave potato cylinders overnight for osmosis to take place.
- Remove potato cylinders and gently roll on paper towels to remove surface moisture.
- Measure length and mass of cylinders again and calculate length and mass percentage change.
Why is distilled water used in investigating osmosis?
It contains no dissolved substances, which could affect the rate of osmosis.
What other plabt can be used in investigating osmosis experiments?
Beetroot or parsnip.
Why do you peel the potato in investigating osmosis?
The potato skin can affect osmosis as it acts as a barrier, making it difficult for water to move through it.
Why do you use a cork baller in investigating osmosis?
So all cylinders of potato are the same in diameter.
Why is 3cm a good length for potato cylinders in investigating osmosis?
If it is too short, we may not be able to measure the effect of osmosis accurately.
Why is it important to gently roll the potato cylinders on a paper towel?
So no water in the potatoes is forced out, it’s just removing surface water.
