The primary difference between a periodic and perpetual inventory system is that a periodic system

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Explanation:

The primary difference between the periodic and perpetual inventory system is that the perpetual system keeps track of things from the start to finish continuously while the periodic system divides it into periods and keeps the records at the end of every set period of time.

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periodic system records these transactions only at the end of the period

Explanation:

A perpetual inventory system is usually described as a method of inventory management that records real-time transactions of received or sold stock by or through the use of technology.

A periodic inventory system which is also known as the periodic inventory method is a method in which the amount of inventory is determined at the end of each accounting period or in specified periods. It is always done through a physical count for each period.

It should be understood that , the perpetual inventory system is generally considered a more efficient method, because it  keeps continual track of inventory balances through the use of technology, while the the periodic system relies upon an occasional physical count of the inventory to determine the ending inventory balance and the cost of goods sold

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.

producers: apple trees, potatoes, carrots, grains, acorns, cabbage, grass, corn, lettuce

consumers: deer, mice, rabbits, chickens, squirrels, horses, worms, cows

predators: eagles, frogs, wolves, owls