A cell needs more than water to survive and reproduce. Use the following forms of transport
across the membrane to answer the questions below: Simple diffusion Osmosis Facilitative
diffusion Active transport Phosphotranferase (group translocation) How does a: cell transport
a lactose molecule ac across its can membrane with the concentration gradient? prokaryotic call
transport a large quantity of glucose across its cell membrane? cell transport an oxygen
molecule across its cell membrane (with the gradient)? cell transport a lactose molecule across
its cell membrane against the concentration gradient? Which of the above forms of transport
require an input of energy to work?
Solution
5. a. Lactose is moving with the concentration gradient. As it is a simple dissacharide sugar
which is soluble in water, it moves inside the cell along with water through diffusion.
b. In prokaryotic cells, sugar transfer occurs through the phosphotranferase system, where
phosphoenolpyruvate is used as the source of energy for transfers of sugars such as glucose,
mannose, fructose wtc.
c. Most gases including oxygen are transferred passively through diffusion across the cell
membrane. The membrane is porous enough for gases to pass.
d. Transfer of lactose against the gradient is done by lactose permease, using energy from the
proton gradient. Thus it is a form of active transport.
Active transport and phosphotranferase system require energy input to work.
across the membrane to answer the questions below: Simple diffusion Osmosis Facilitative
diffusion Active transport Phosphotranferase (group translocation) How does a: cell transport
a lactose molecule ac across its can membrane with the concentration gradient? prokaryotic call
transport a large quantity of glucose across its cell membrane? cell transport an oxygen
molecule across its cell membrane (with the gradient)? cell transport a lactose molecule across
its cell membrane against the concentration gradient? Which of the above forms of transport
require an input of energy to work?
Solution
5. a. Lactose is moving with the concentration gradient. As it is a simple dissacharide sugar
which is soluble in water, it moves inside the cell along with water through diffusion.
b. In prokaryotic cells, sugar transfer occurs through the phosphotranferase system, where
phosphoenolpyruvate is used as the source of energy for transfers of sugars such as glucose,
mannose, fructose wtc.
c. Most gases including oxygen are transferred passively through diffusion across the cell
membrane. The membrane is porous enough for gases to pass.
d. Transfer of lactose against the gradient is done by lactose permease, using energy from the
proton gradient. Thus it is a form of active transport.
Active transport and phosphotranferase system require energy input to work.
