All living forms on earth i.e animals and plants are active.
They have phases like birth, growth, reproduction and death.
The activity is due to the physiological and metabolic processes happening inside their bodies.
Their bodies are made up of groups of cell which is basic unit of life.
All the above physiological activity happens at the cell level.
The cell has many cell organelles within to carry out the physiology and metabolism required to stay alive.
Also check out: → List of cell organelles and their function.
But the plant and animal cells do not have similar stages and physiological roles life. Even the purposes are also different.
Plant cell phases: Based on their cell phases or life stages, The early cells are called parenchyma. These cells form tissues in plants and get differentiated to form new formed tissues. This tissue and has a great potential to grow.
The next stage of the cells is collenchyma. This collenchyma tissue has no potential to grow but has physiology and it has very long life span. It is terminiated by next stage when cells convert to sclerechyma.
The last stage of plant cell life is sclerenchyma. Sclerenchyma has only dead cells but it is not removed from the plant body. Instead it is used to give hardness and support to plant.
This sclerenchyma cell is made hard due to deposition of dead substance namely legnin. It also supports other functions of plant by being converted to xylem, phloem etc. Here xylem is a water conducting channel and phloem is food conduction channel to whole plant. Since there is no circulatory system in plants, these channels serve the purpose.
So the trend in plant cell life is that parenchyma converts to collenchyma and then as they age they convert to sclerenchyma.
Animal cell phases: Animal cell has no such phases. They just are born, grow, perform normal physiology and die. The dead ones are replaced by new cells. Dead cells are removed of the body unlike in plants.
Animal cells and plant cell are similar to a great extent in terms of structure and physiology. Plants have small variation like presence of outer rigid cell wall, chloroplast for synthesis of own food by use of sunlight, presence of duct like cell structures to move water and other essential elements through their large and long bodies etc. Xylem is meant for water transport and phloem is meant for food transport. Their hormones that influence their physiology are different than animal’s cells.
Food: In animal cell, the food is supplied by some external source and transported by blood. So for food animal cells depend on some source while most plant cell synthesize their own food.
Excretion: waste of animal cell is removed of the cell and carried outside the body. In plant cell, the waste is stored inside the cell or in the vicinity of the cell. This is then stored as alkaloids or other waste like in leaves which wither away.
Respiration: In both plants and animals respiration is by mitochondria and energy is from combustion of carbohydrates in presence of oxygen. For more details on respiration read article on mitochondria and its characters .
Multiplication: Cells in both animals and plants multiply in their number by mitosis or meiosis. The difference is that mitosis gives rise to two new cells with same genetic trends as parent cell while meiosis gives four cell with half of the genetic trait of parent cell. Mitosis is for cell replacement while meiosis is for reproduction.
Cell death: In plant cells, the cells gets signified with age and lose the internal contents. This adds strength to plant though cell is dead. In animals the cell death results by apoptosis and necrosis.