Question

Why are vacuoles absent in animal cells?

Answer 1

A cell's cytoplasmic matrix contains a membrane-bound structure called a vacuole. Tonoplast is the membrane that surrounds the vacuole. The contents of the vacuole, referred to as the cell sap, differ from the cytoplasm surrounding it. Phospholipids are the main constituents of membranes. Proteins embedded in membranes aid in the movement of molecules across the membrane. Vacuoles can contain a variety of materials or diverse combinations of proteins.

Complete answer:
Animal cells have vacuoles; however, they are smaller in size than plant cells.
Vacuoles are membrane-bound cell organelles found in both plant and animal cells, as well as some fungal, protozoan, and bacterial cells. Animal cells have smaller vacuoles than other cells since they don't need to store as much water, both organic and inorganic, for proper operation.
It's partly due to the inevitable evolutionary trade-off. Animal cells are part of a bigger organism that can relocate to find water, food, and other necessities. If animal cells had vacuoles, acquiring critical nutrients would necessitate a significantly higher degree of ATP (energy) expenditure. Plants, on the other hand, are fixed and must find different ways to store vast amounts of water because they do not move.
Nutrients and water are stored in vacuoles, which a cell can rely on for survival. They also store the cell's waste and keep it from becoming contaminated. As a result, it is a vital organelle.

Note:

PLANT CELL	ANIMAL CELL
Square or rectangular in shape	Irregular or round in shape
Cell wall is present	Cell wall is absent
Lysosomes are present but very rare	Lysosomes are present
Centrosomes are absent	They are present
Mode of nutrition is Primarily autotrophic	It is heterotrophic