i do not know for sure(i did not ever look directly to the cell-hei i don’t have practicum about general biology… 😕 …)
but i think it would moved by cell it self, depend on the intencity of light which is got by cell (look at its cloroplast, use the different intencity of light)

hope this is help
______
aw..
knw..
i jus.. fun

Hi! I saw chloroplasts moving into vegetable cell in a Botany Course when I swich on the light of microscope but I don’t know how they move. Anyway they move toward light source.

That is correct chloroplasts have positive phototactism. Their movement is also influenced by osmotic pressure, citoplasmatic currents and general chemical composition of the cytoplasm

ho..
this make me more …. (uh what a big interest)
next time i should get it better

The chloroplasts are lens-shaped organelles found in leaves and other green organisms. In the green tissue, in the interior of the leaf, are mesophyll. Each mesophyll has about 30 or 40 chloroplasts. Chloroplasts are made up of saclike photosynthetic membranes. These membranes are in such an order that they form stacks called grana. Next to the grana are thylakoids which separate the grana from the stroma, the fluid out side the thylakoid. Inside the grana are the pigments involved in photosynthesis. The pigments in the chloroplast are called chlorophyll.

The chloroplasts are photo-, photo-, let me get my notes! OH, they are phototaxic. Jeez, took me ten minutes to find it. Phototaxic means they move towards the light. A crude example would be bugs to a bright light source. Bugs, like chloroplasts, are phototaxic. This is why the plant will face the light source no matter where you place it. They will do this so they can increase their chloroplasts’ exposure levels. Hope I was of help.

How does the flow of the cholorplast change the direction of the leaf? Isn’t that a seperate process?

they flow around the center of the cell in a direction inside the cell.the speed depends on temperature.osmotic pressure.and something else.

the direction is changeable~~

Of course it it. the changing of the direction of the leaf is called positive phtotropism and it is done with auxin. Toatlly different process

Figured as much!

Soooo….I’m interested in knowing how exactly the plant redirects it’s leaves in the direction of sunlight. How does it know which direction the intensity is greatest in?

Auxins. Check out our tutorials for the explanation- look at phototropism:
http://www.biology-online.org/3/5_plant_hormones.htm