(a)(i) The four levels of organisation in living: organisms are: Cell, tissue, organ, system
(ii) A cell is a basic structural and function unit of life; it is bounded by a membrane containing nucleus and cytoplasm. Some cells are capable of independent existence, carrying out all the characteristics or life processes in living things. They may have processes like pseudopodia, cilia, flagella, etc. Cells also have inclusions, referred to as organales.
A tissue is a collection of cells which are similar in structure and perform similar functions. Some tissues cannot exist on their own but some can live on their own, e.a., Hydra. They have the same origin and occupy the same position in the body of the organism.
An organ is a collection of different tissues that perform a common function or functions. Some organs carry out a single function. e.g., heart while others carry our more than one function, e.g., kidney.
A system; is made up of different organs that perform a particular function. Systems are peculiar to higher organisms.