I saved some seeds from a store bought passionfruit and i am wondering whether they will produce plants that have the same large purple fruit i bought?
Yes, they do grow true from seed (or nearly so; there are a number of cultivated forms, but they are reasonably similar and you will certainly get a plant that produces edible fruit if grown in the right conditions).
The plant is a vigorous perennial climber and must be protected from frost (a little cold will cut it down to the ground, it will regrow in the spring - a bit more cold will simply kill it entirely).
The flowers are spectacularly beautiful - worth growing the plant just for them.
just a note…it may not fruit the first year depending on the conditions. i started one out in a pot indoors and the vine got very big over one year. we had to move it out to a greenhouse and it flowered and gave fruit the second year, after it took over a whole corner of the greenhouse.
ooh and another note, if you have problems germinating the seed, try filing away a tiny part of the outer seed shell to let the moisture in more quickly.
Thanks Mangetout&kryptonite2 
I think I’m right in saying that it should fruit on new growth (although as kryptonite2 says, it may not fruit on the first year’s growth), so a little bit of pruning in April (just before it starts up growing again) should make it bush out and hopefully produce more fruit.
If you’re keeping it in a pot, you’ll need to feed it with fertiliser, as it is a fast-growing and hungry plant - rake half a tablespoonful of either blood/fish/bonemeal or slow-release granules into the top of the compost (assuming a 10+ inch pot in the second year of growth) and occasionally feed with diluted liquid tomato fertiliser once the flowers start to appear. Stop feeding the plant before growth stops in the autumn and water sparingly through the winter.
The seed can be a little slow to germinate; I recommend putting a dozen seeds or so into a three inch pot and covering with a quarter inch of potting compost, water a little (to leave the compost just moist, not waterlogged) and seal the whole thing in a transparent plastic bag - leave it in a warm place (if you have a cupboard with a hot water tank in it, that would be ideal) and inspect every few days - bring it out into the light when the first seedling appears - others will follow soon after. The seedlings are very soft and sappy, so best to hold off transferring them into individual pots until they are at least six inches tall and have a few true leaves.