chapter 3 Flashcards
Define diffusion
The net movement of particles from a region of higher concentration to a region of lower concentration due to random motion, down a concentration gradient
Where does energy for diffusion come from?
Energy for diffusion comes from the kinetic energy of random movement of molecules and ions.
How do substances move in and out of cells?
Some substances move in and out of cells by diffusion through the cell membrane
Why is the diffusion of gases and solutes important in living organisms?
- It allows living organisms to obtain daily requirements like oxygen and glucose
- It helps get rid of waste products like carbon dioxide.
Name and describe the factors affecting diffusion
- Distance
- The shorter the distance , the faster the rate of diffusion
-e.g Alveoli have thin walls to ensure faster rate of diffusion
- The shorter the distance , the faster the rate of diffusion
- Concentration gradient
- The greater the difference in concentration , the faster the rate of diffusion
- Surface area
- The larger the surface area , the faster the rate of diffusion
- Temperature
- The higher the temperature, the greater the kinetic energy. Molecules will gain energy and move faster resulting in a faster rate of diffusion.
- Size
- Smaller particles can diffuse faster
- Small particles can diffuse across the partially permeable membrane.
Name the functions of water
- Cool down / regulate body temperature ( by sweating )
- Acts as a solvent ( dissolve chemicals for chemical reactions that take place )
- To transport nutrients and oxygen throughout the body
- Removes waste product ( urea dissolves in water to form urine )
- Moisten tissues
- protect tissues organs and body
- Helps prevent constipation in excess solvent
- Lubricating joints
- Lessen burden for kidney and liver
- Important solvent for metabolic reaction
- Hydrates body
Define Osmosis
The net movement of water particles from a region of higher water potential (dilute solution ) to a region of lower water potential ( concentrated solution ) through a partially permeable membrane.
How does water move in and out of cells
by osmosis through cell membrane
Describe the processes of hypertonic and hypotonic in animal and plant cells
Hypertonic ( concentrated solution )
Animal :
-Solution has lower water potential that animal cell
- So water moves out of cell by osmosis
- cells SHRINKS AND SHRIVELS
- Process known as crenation
Plant :
- The plant cell will lose its turgidity, lose its turgor pressure , vacuole decreases in volume, cell membrane shrinks and pulls away from cell wall.
- process known as plasmolysis
Hypotonic ( dilute solution )
Animal :
- Solution has higher water potential than cell
- Water moves into cell by osmosis
- Cell will burst, process known as haemolysis
Plant:
- plant cell will not burst cuz of cell wall
- it becomes turgid as cytoplasm and vacuole swell and presses against cell wall
Define active transport
The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration against a concentration gradient, using energy for respiration
State the importance of active transport
Active transport is vital process for the movement of molecules or ions across membranes
E.g uptake of glucose by epithelial cells in the villi of the small intestine and by kidney tubules in the nephron
uptake of ions from soil water by root hair cells in plants
Explain the function of protein carriers in active transport
Active transport uses carrier proteins embedded in the cell membrane to pick up specific molecules and take them through the cell membrane against their concentration gradient.
