First layer fine but the print ends flakey

I just completed building my first ever 3D printer a RepRapPro Mendel. I am attaching the images of my first print.
The printer prints fine at first but towards the end the print starts losing consistency. I am using PLA that came with the kit with the hot end at 200C and the bed at 56C. I turned off the bed heater after the first 5-10 layers.
What I want to know is that if the error I am seeing in the print is because of:
1. Me turning off the heater bed
2. The printed object cooling, i.e. I need to put a fan on my machine
3. Error in slicing
4. extruder not outputting enough plastic
or any other error.

Your first layer looks like a raft.
The lines for the first N layers should be 100%, one line next to the next line.
There must be something wrong with your calibration or slicer settings.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

OK, I had separately sliced the .stl file using slic3r and not use the gcode file pronterface made for me. I think that might cause the first layer to be like that. Let me try with the gcode file made by pronterface. Hopefully it'll fix the other error also.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse