Theory question 104
Cell Structure and Organisation(a) (i) What is a cell?
(b) Describe the structure and state the function of each of the following:
(i) Nucleus; (ii) Mitochondrion
(c) (i) Make a labelled diagram 8 cm to 10 cm long of the Euglena.
(ii) List three animal-like features and two plant-like features of Euglena.
Show the model answer
(a)(i) A cell is the basic structural and functional unit of life: a mass of protoplasm (nucleus and cytoplasm) enclosed by a cell membrane.
(b)(i) Nucleus – structure: a round or oval body bounded by a double nuclear membrane with pores, containing chromatin (chromosomes) and a nucleolus in nucleoplasm. Function: controls all activities of the cell; carries hereditary information (genes); controls cell division.
(ii) Mitochondrion – structure: a small rod-shaped or oval organelle with a double membrane, the inner membrane folded into cristae, filled with a matrix. Function: site of aerobic respiration, where energy (ATP) is released.
(c)(i) Diagram labelled: flagellum, gullet (reservoir), eyespot (stigma), contractile vacuole, chloroplasts, nucleus, nucleolus, paramylum (starch) granules, pellicle, cytoplasm.
(ii) Animal-like (any three): has a flagellum and moves about; has a flexible pellicle, not a cellulose wall; has an eyespot; has a contractile vacuole; can feed heterotrophically (saprophytically) in the dark; has a gullet.
Plant-like (any two): has chloroplasts with chlorophyll; makes its own food by photosynthesis (holophytic); stores food as paramylum, a starch-like carbohydrate.
For each organelle give both its structure and its function.