Living Environment Translated Arabic 2014 | Page 38

i. Inorganic compound are made of elements other than carbon.
Examples are water ( H2O) and carbon dioxide ( CO2).
j. Water is one of the most important inorganic compounds for
living things.
k. Cells take in substances and release waste through their cell
membranes.
l. Cell membranes are constructed like a sandwich. Lipids make
up the top and bottom layers with proteins as the middle
layer.
m. The three types of cell membranes are:
1. Permeable- everything moves in and out freely
2. Semi-permeable (selectively permeable)- some molecules
move in and out while other do not.
3. Impermeable- nothing moves in or out through the
membrane
n. Passive Transport moves materials through a membrane
without the use of energy. Materials always move from an
area of HIGH concentration to an area of LOW concentration.
o. Diffusion and osmosis are types of passive transport.
p. Active transport moves materials through a membrane with
the use of energy. Materials move from an area of LOW
concentration to an area of HIGH concentration.
q. Endocytosis is the process of taking substances into the cell by
surrounding it with a cell membrane.
r. Exocytosis is H