Movement of Molecules In and Out of Cells Flashcards
What is osmosis?
Movement of water from a dilute solution to a more concentrated solution through a partially permeable membrane
How do dissolved substances move in and out of cells?
Diffusion and active transport
What is the effect of osmosis?
Gradually dilute a solution
Give an example of osmosis in plants
In root hair cells, water moves from soil into cell by osmosis along the concentration gradient
What is lost through sweating?
Water and ions (salts)
What would happen if ions and water is not replaced after exercise?
Body cells would not function efficiently
Why do sports drinks usually contain high amounts of sugar?
To replace the sugar used in energy release
What is active transport?
The movement of substances from and area of low concentration to an area of high concentration (against the concentration gradient) using energy
How are villi in the small intestine adapted to exchange materials effectively?
Large surface area to increase diffusion sites
Rich blood supply to maintain concentration gradient
Thin walls to provide short diffusion pathway
How does the small intestine exchange substances?
Diffusion
Active transport
How are alveoli in the lungs adapted to exchange substances efficiently?
Large surface area to increase diffusion sites
Rich blood supply to maintain concentration gradient
Thin walls to provide short diffusion pathway
How are substances exchanged in the alveoli?
Diffusion
What substances diffuse in the alveoli?
Carbon dioxide from blood into alveoli
Oxygen from alveoli into blood
What is the proper name for the windpipe?
Trachea
Describe how air moves into the lungs
Intercostal muscles contract causing the Ribcage to move outwards are upwards
Diaphragm moves down
Increases volume of lungs which decreases pressure causing air to be drawn in
Describe how air moves out of the lungs
Intercostal muscles relax causing the Ribcage to move inwards are downwards
Diaphragm moves up
Decreases volume of lungs which increases air pressure, forcing air out
What is the name of the process where water vapour is lost in plants?
Transpiration
What is transpiration?
Evaporation of water from plants (through stomata)
How can the guard cells affect how much water is lost?
The size of the stomata is controlled by the guard cells
If plant looses water faster than it is taken up by the roots, the stomata can close
Prevents wilting and dehydration
What weather conditions does transpiration happen fastest?
Hot, windy and dry because the stomata are closed to prevent diffusion so photosynthesis has to stop
How does a negative pressure breathing aid force someone to breath?
Causes chest to rise due to reduced pressure outside chest
How does a positive pressure breathing aid force someone to breath?
Forces air into the lungs
How does wind speed affect transpiration?
As wind speed increases, transpiration increases because water evaporates faster from the surface of the leaf. The concentration gradient is increased
How does humidity affect transpiration?
As humidity increases, the rate of transpiration decreases because less water evaporates as the air is already full of water. The concentration gradient decreases.
How does an increase in temperature affect transpiration?
The rate of transpiration increases because it increases the rate of evaporation.
