(i) Make a labelled drawing of a typical plant cell to show its essential features.
(ii) Give the functions of two labelled organelles
(b) Describe briefly two levels of cell organization in living organisms giving an example of each type.
(c) What role do the following processes play in the activities of a living cell (i) osmosis; (ii) diffusion.
Explanation
(ii) Functions of two organelles are :
Mitochondrion — This serve! as centre for cell respiration. It is often called the cells power house. Glucose is broken down here and stored as A. T. f (Adenosine triphosphate) and released as needed by the reE of the cell.
Chloroplast — It possesses the green pigmer chlorophyll. Therefore, it is the site of photosynthesis.
(b) Two levels of cell organisation in living organisms are:
Tissue This is a group of cells that are similar in structure and function It performs specific functions in living organisms. Examples tissues in plants are xylem, phloem, mesophyll, etc. In animal we have the bone, cartilages, etc.
Organ — This is a group ( several different tissues with special functions e.g. in plant we have the root, leaf, stem etc and in animals we have th heart, eye, lungs, skin, ears, liver, etc.
(c)(i)Osmosis is responsible for the movement of water or materials from one cell to another, usually from low( concentration to higher concentration, e.g. absorption of water or mineral salts from the soil by the root hairs. animals, it is responsible for the movement of water into the contractile vacuole in paramecium.
(ii) Diffusion play important roles within an organism and its environment, e.g. gaseous exchange in organisms, exchange of nutrient from maternal blood, diffusion of food from the placenta to the foetus, transfer of food and oxygen from the intestine into the villi and from the tissue fluids into the cells.