why plants do not need a digestive system like us?
Plants do not have a digestive system because their need for nourishment is fulfilled through the process of photosynthesis and cellular respiration. They obtain their energy and and nutrients from the energy of the sun to create their supply to live. Therefore using characteristics such as the sun and water their physical nature does not allow them to rely on a digestive system to obtain their need for energy, when their need is supplied almost directly for the sun.
Plants donot need a digestive system like humans because we humans depend on organism that either make their own food or has food. When we eat it, our body needs to break down the food to is basic component ei fat, carbohydrates, minerals, and proteins. Thats the only way we can absord these basic component into our system so we could use it (other than via intravenous of course).Plants on the other hand, only rely on light, some gases, and basic minerasl (note that these components are simple enough to be absorb thru their roots and leaves. Once these are provide to the plant, with its clhroplast it can easily make its own food - glucose.
The plants are way different from us....maybe in many ways! and here is one more case
The plants take in the raw materials which are required for it, and they are:-
water, carbon dioxide
now as it takes this directly....it starts performing photosynthesis in the presence of sunlight and chlorophyll......and thus it gets its nutrition directly without digesting it. and the other reason is that it prepares its own food....while we do not.
While we directly do the intake of food and digest it to get energy from it later.
Hope you understood.