What do you learn about global water supplies?
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1. Most water we use goes to agriculture

Agriculture places significant pressure on the world's fresh water, accounting for nearly 70% of all water withdrawals. That number can rise to more than 90% in countries like Pakistan where farming is most intensive. Unless substantial efforts are made to reduce food waste and increase the water-use productivity of farming – to get more “crop per drop” – water demands in the agricultural sector are projected to increase in the coming years to keep up with population growth.

Explanation:hope you like this

To prevent the backflow of blood during systole and diastole, Artries from the heart dont need valves since their blood pressure is already high enough to not allow backflow of blood, but since veins' blood pressure is lower, they need valves just so the blood doesn't seep back in into the heart again!