nutrition in leaves

Hi everyone, i have two or so questions that need to be answered..

The first one is, can lack of nutrition to a plant kill the plant or weaken it by alot? Also, will buds be less potent etc etc..? I first started seeing the leaves at the bottom of my plant turn really yellow, and now they look like they can fall off. But i have noticed a slight yellow shade starting to appear on leaves higher up the plant. What could this be due too?

Thanks

definatly sounds like you have nutrient defficiency. A plant will grow without it but you will not get a good yeild and run into plenty of problems. Go out and get some fertilizer but make sure it has micronutes or that will cause more problems(like the light green in your leaves). On the net you can also find microblast which is great if using fertz that do not contain them. Only give them about half of dose it will say for indoor plants. Try to stay away from mircale grow too!

I've got a solution called BabyBio, this has worked well in the past. But how often do you think i shud use it on my plant?
Remembering not to overwater it.