Why is it that we need air and food?
491197
both are needed for cellular respiration\n\noxygen + glucose(food)--> carbon dioxide + water+ energy
171929
Birds air sacs allow them to have a larger "lung" capacity, therefor if humans had air sacs we would be able to run the mile in a shorter time b/c our bodies would theoretically be able to take in more oxygen.
431051
Body energy, necessary for breath, motion, heartbeat, thinking, and all that, comes from food. Chiefly from two components of food, in fact. Carbohydrates are made of carbon and hydrogen (sugars, starches, etc), and fats (oils) which are more complex shemically (butter, olive oil, etc).\n\nTo produce the energy cells need in the form they need it, to do their function, these are burned (in a clever and flameless way) indside the cell. The end products of complete oxidation are carbon dioxide and water. The oxygen necessary comes from air, through the lungs. \n\nThe more energy your muscles need (because of exercise) the more fuel is burned and the more carbon dioxide and water is produced. The carbon dioxide is exhaled (through the lungs) and the water is excreted by the kidneys. Both are carried by the blood from the muscles to the lungs or kidneys as needed. \n\nSo the more your exercise, the faster you breath and the more oxygen you take in and the more carbon dioxide you exhale. If you run for one hour, you'll produce a certain amount of carbon dioxide and if you run for 2 hours you'll produce just about twice as much. but, even if you're sleeping, you'll still produce carbon dioxide for many parts of your body still have to do some work even if you're not running around. Your heart still beats, your brain still works (dreams, maybe) and you still stay about the same temperature. All that takes energy, just not so much as you need when you're running. \n\nAnother source of carbon dioxide, a much bigger source than humans running around on a soccer field, or a baseball diamond, is burning fossil fuels. Gasoline, diesel fuel, coal, heating oil, ... all produce carbon dioxide and water (and heat) as exhaust products. All that carbon dioxide being put into the air is one of the causes, most people think the major cause, of the rise in average temperature on the Earth. This is the global warming that's been in the news.
875973
your metabolism, the rate that your burn food, makes the adjustment for us.\n\nnow i am hungry! wanna go for pizza?
371493
to carry nutrients, oxygen, wastes to/away from body cells.
255440
Food consumption has gone global. ppl eat more bcoz they hav so many things to choose from and also these things are very cheap. Packaged products etc has caused cases like obesity to rise. When ts bringing more employment, its also bringin a health crisis.
625495
You have it right. Your body needs some water to help digest your food. For one thing, the food we eat has vitamins and minerals. Some of those are water soluable and need some watery substance to digest them properly. Especially if you are taking a multi vitamin with food.
772466
That is why you have to eat a diverse diet. Different foods have different proteins and our bodies get the proteins needed from the food we eat.
365298
we can live without anything for 3 seconds then somethings we will need. Air, water, and food.
406756
Hmmm. Here goes:\n\nPlants need carbon dioxide, water and sunlight.\n\nHumans need oxygen, water and everything else.
380835
your body absorbes the liquid from the food you eat...waste is then produced...aka poo :)
40675
The source of energy is food. Food is digested, giving you energy.
496597
What we have here is a false dichotomy. There is no reason why we can't do BOTH. I see both those next door and those in the next continent as my neighbors. I care for both equally. Too often we value the lives of our own countrymen more than those who are not. I think that's wrong. There is absolutely no reason why anyone on this planet need go hungry. The earth produces FOUR TIMES the amount of food necessary to feed every individual on this planet. The fact that there are starving people anywhere can mostly be blamed on greed and misplaced priorities on the part of world governments. If we work to solve the problems of the poorest among the human population, we will simultaneously improve conditions for those in more affluent places like the USA, Britain, UAE, etc. The average person in these affluent countries throws away more nutritious food than the average person in a third world country receives as food. It's this sort of thing that we need to change in order to feed the hungry here and elsewhere.
130627
Of those water is the most important. If need be we could survive for about a month without eating, living only off of our fatty reserves. Shelter would reduce the amount of water we would require to survive, say in a desert, but even still we couldn´t survive for many hours completely without water.\nIf you are in a spaceship and all your oxygen disappeared you would die within minutes...
985658
So living things can breath. Without air pressure we would not be able to breath.The air is thinner up in the atmosphere.Down here the air is Thicker and more dense then up there that's how we can live,with air pressure.With too much pressure or to little we could die.With too much pressure we could implode. Or too little pressure we could explode (I don't know how that would be possible but I think it's right) .That sounds funny that we would explode with too little
447229
ALL human beings inhale atmospheric air, absorb its oxygen, and exhale carbon dioxide.\nOn the other hand, ALL plants intake atmospheric air, absorb its carbon dioxide, and exhale the oxygen - which proves beneficial to humankind !
973307
Because cells must keep an optimal surface area:volume ratio in order to be able to receive food and transport it throughout the cell effeciently. If they grew too large, they would starve and die.