(a) Study carefully specimens A, B, C, and D. copy and complete the table below Specimen Part modified to form specimen Mode of propagation Stored material ...
Question 1 Report
(a) Study carefully specimens A, B, C, and D. copy and complete the table below
| Specimen | Part modified to form specimen | Mode of propagation | Stored material |
| A | |||
| B | |||
| C | |||
| D |
(b) In a tabular form state four observable differences between specimens A and C.
(c) Crush a small portion of specimen D and divide it into three equal parts. (i) Place a portion on a white tile and add two (2) drops of iodine solution.
(ii) Place another portion in a test tube and add one (1) ml of distilled water and shake. Add few drops of sodium hydroxide solution and shake again. Slowly add a few drop of 1% Copper (ii) sulphate solution. (iii) Smear the third part on a filter paper, leave for about five (5) minutes and observe carefully
Answer Details
The specimens are organs of vegetative propagation. A common WAEC set is: A, onion; B, ginger; C, Irish potato; D, cassava. The completed table follows that reading.
(a) Completed table
| Specimen | Part modified to form specimen | Mode of propagation | Stored material |
|---|---|---|---|
| A (Onion) | Modified leaves (fleshy leaf bases) forming a bulb | By bulb | Carbohydrate (sugar) / starch |
| B (Ginger) | Modified underground stem (rhizome) | By rhizome | Starch |
| C (Irish potato) | Modified underground stem (stem tuber) | By stem tuber | Starch |
| D (Cassava) | Modified root (root tuber) | By root tuber / stem cutting | Starch |
(b) Four observable differences between specimen A (onion bulb) and specimen C (potato stem tuber)
| Specimen A (onion) | Specimen C (Irish potato) |
|---|---|
| Formed from modified leaves | Formed from a modified stem |
| Made of concentric fleshy scale leaves | Is a single swollen solid structure |
| Has one main (terminal) bud | Has several buds (eyes) scattered over its surface |
| Food is stored in the fleshy leaf bases | Food is stored in the swollen stem tissue |
(c) Tests on the crushed specimen D (cassava)
| Test | Observation | Inference |
|---|---|---|
| (i) Portion + two drops of iodine solution | Turns blue-black | Starch is present |
| (ii) Portion + distilled water + sodium hydroxide + copper (II) sulphate | Remains blue (no purple colour) | Protein is absent (or present in only a trace) |
| (iii) Portion smeared on filter paper, left five minutes | No permanent translucent (grease) spot | Oil / lipid is absent |
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