Questions about " that"

[bosunyum]

The following sentence is taken out from the story titled " who lives longer?"
my first question is

1. Eating less has a more pronound effect on the aging process than does any other lifestyle chage. It is the only factor we know of in laboratory animals that is an anti-aging factor. In the second sentnece " That" is a relative pronoun or a conjuntion? Also, what is the meaning of secone sentnece and is it grammatically accpetable sentnece? Help me!!!!!!!!!!

2.A long life s not just the result of being good to your body and staving off disease. Here , what does it mean by being good to your body?

3.Factors associated with the coronary problems were suppressed hostility, having a nonsupportive boss, and decreased job mobility. What does this sentence mean? And especailly, what does it men by having a nonsupportive boss? Does it mean the nonsupprotive boss caused hostility?

PLESE HELP ME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Tdol]

1- relative pronoun ( you could replace it with 'which')
It is correct and it means that eating less is the only known things that reduces the aging effects in lab animals.
2- taking care, not doing harmful things
3- A boss who doesn't support you, so that you feel unsure and insecure at work. The boss may be a factor in the suppressed hostility, but in the sentence, it isn't stated that way- you may feel hostile towards other workers, etc. In all, if you are angry, but don't express it, have little chance of finding another job and have a boss who doesn't care, you might have heart problems.

[bosunyum]

Thanks Todol, but I still have another question about the first one. If that is a relative noun what does it modify? does it modify animals or what?
Looking forward to seeing your reply!

[Casiopea]

Firstly, "that" couldn't be a conjunction. It functions as the subject of "is",

1. . . . that is an anti-aging factor.

Secondly, "that" refers back to "the only factor",

1. It is the only factor that is an anti-aging factor.

Thirdly, "the only factor" refers back to "It" ("Eating less"). So,

1. Eating less is an anti-aging factor.