It is so interesting that my immediate response to your question was so different from what you asked for in your first post!  I'll include it here just for the sake of interest:

My immediate response to your question: "What do you think of when you see/hear the words life and death?"  I immediately think of the phrase "life or death situation."  In other words, I think of a tragic situation where a human being is forced to make a choice between life or the end of their life.  It often involves great moral quandary as to whether that person would save herself or others.

My eventual response after reading your first post:  This is a very personal question with no right or wrong answer for anyone, of course.  That being said, for me, life can be described as existing from the moment of conception.  Life is vibrant.  Life is being cognisant of oneself.  Life is thought.  Life is happiness.  Most importantly, life is the greatest gift that God has given us.  Conversely, death is the end of life.  Death is dullness.  Death is swirling in nothingness.  Death is the absence of thought.  Choosing death (as in a crime such as murder) is taking away that great God-given gift of life. 

What do you think of when you see/hear the words life and death?

What can life or death be described as.  For example: When there is a loud noise, I think of death.  As in, a bomb.  It's loud and it can kill people.

Though some would say that life and death are opposites, I see similarities.

Both life and death are common to the human (or any organism for that matter) experience. 

Both life and death are miraculous and amazing, almost incomprehensible but yet very common.

For example, its amazing that in a second, a human life is created that never existed before.

Also in a second, a life no longer exists...

The two are both mind boggling.

This is certainly an interesting and thought-provoking question.  And, the answer is going to be completely different for everyone, based on their own personal experiences with life and death.  For example, if someone has had a loved one pass away, when they hear the word death they might think of a funeral, a coffin, or funereal flowers.  If no one has had a loved one pass away, they might think of death more abstractly, as in autumn leaves falling to the ground, or a driving by a graveyard.

For me, life brings to mind vibrant colors-cobalt blues, deep purples, crimson reds.  It brings to mind spring and birds singing, thunderous rainstorms, and the smell of a baby's skin.  It brings to mind the sound of children's laugher.  I can hear a heart beating, and feel the warm pulse under my fingertips.  Death brings to mind the smell of dark, mildewy undergrowth in a forest, dark skies, the heavy oppressive humidity and calm before a large storm.  I can hear a funeral parlor's somber organ notes and the sound of muffled weeping.  I imagine a crack of lightning-it reminds me of how death can strike anywhere, at any time, and its powerful emotional toll on people's life.  Granted, I am poetical by nature, so images like this suit my personality more than it might some other personality.  Any of the ideas that you come up with-including your bomb idea-can be used to write a really great poem.  I hope these thoughts help a bit with whatever assignment you are working on.  Good luck!