Well, I don't fully understand your question. I think I know what you're getting at though.
In a system of sexual reproduction, you have genes coming from both an egg and the sperm. Therefore, it'll only contain half the total amount of chromosomes (46 in humans). A sperm will have 23, and the egg will have the other 23. Is that what you meant why the chromosomes are cut out in pairs? If that wasn't your question, please elaborate and I'll return to answer it to the best of my capabilities.
The deer and wolf population would decrease because the deer have less plants to feed on while already being eaten by the wolves, and eventually the wolves will have less deer to feed on which will decrease their population
Venus is the answer, you can tell easily because Venus has no moons or rings :)
Answer: C) They can contain contaminants that can enter the air during storms or high winds.
Explanation: A is wrong because I got it wrong (Sorry, can't give much explanation there).
B is wrong because water contamination does not directly relate to respiratory health.
D is wrong because fertilizers can impact respiratory health (Explanation seems lack-luster, but I feel like this is common sense).
Hope this helps :)
Humans Come From A Guy Sperm It Goes Into The Females Egg