For a classroom activity, class 6 students collected pond water samples from near their school. The water looked dirty and greenish, yet they couldn't spot any organism with the naked eye. Their Biology teacher then helped them observe the samples they collected under a microscope. To their surprise, they saw tiny organisms that had no visible legs or hands but showed quick movements.
Answer the following questions :

(i) Identify the organisms based on the clues :

(a) Irregular-shaped, unicellular animal.

(b) A unicellular, slipper-shaped animal that moves with the help of cilia.

(c) A unicellular plant with flagella.

(ii) Mention one biological function that occurs in both unicellular and multicellular organisms.

(iii) Why do cells differ in their shapes?

(i) The organisms based on the clues :

(a) Irregular-shaped, unicellular animal is Amoeba.

(b) A unicellular, slipper-shaped animal moving with cilia is Paramecium.

(c) A unicellular plant with flagella is Chlamydomonas.

(ii) Respiration occurs in both types of organisms to release energy from food.

(iii) Cells differ in shape because cell shape is determined by the function of the cell.