Ø is the transport of substances across the cell membrane
(49) against a concentration gradient.
Ø It involves (50) carrier proteins. Only substances that fit the (51) shape of the carrier proteins can be transported by active transport
Ø is an (52) active process and requires energy. Therefore it only occurs in
(53) living cells which can release energy by (54) respiration (呼吸作用).
Ø Active transport is important for obtaining useful substances, e.g. the absorption of:
n nutrients like (55) glucose / amino acids / lipids in human small intestines
n (56) minerals from the soil into the roots of plants.
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html (動畫: 鈉鉀泵)
http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter38/animation_-_mineral_uptake.html (動畫: 主動吸收礦物質)