TEST OF PRACTICAL KNOWLEDGE QUESTION
(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
Identification of the specimens: The four specimens are all organs of vegetative (perennating) propagation. Specimen A is the stem of a cactus, specimen B is an onion bulb, specimen C is a ginger rhizome, and specimen D is a carrot.
(a) Completed table
| Specimen |
Part modified to form specimen |
Mode of propagation |
Stored material |
| A |
Stem |
Stem (stem cutting) |
Water / carbohydrate |
| B |
Shoot (fleshy leaf bases) |
Bulb |
Water / sucrose |
| C |
Stem |
Rhizome |
Water / starch |
| D |
Root |
Root tuber |
Water / starch / sugar |
(b) Four observable differences between specimen A (cactus stem) and specimen C (ginger rhizome)
| Specimen A (Stem of cactus) |
Specimen C (Rhizome of ginger) |
| Green in colour |
Brown / grey-yellow in colour |
| Flattened in shape |
Cylindrical in shape |
| Leaves reduced to spines |
Leaves reduced to scales |
| Nodes and internodes not distinct |
Nodes and internodes distinct |
| Adventitious roots absent |
Adventitious roots present |
| Terminal buds absent |
Terminal buds present |
(Any four of the paired differences above are acceptable.)
(c) Test for food substances in specimen D (carrot)
| Test |
Observation |
Inference |
| (i) A portion of D on a white tile + 2 drops of iodine solution. |
A blue-black colour is formed. |
Starch is present. |
| (ii) A portion of D + 1 ml distilled water, shake; add a few drops of sodium hydroxide (NaOH) solution, shake; then add a few drops of 1% copper(II) sulphate solution. |
No colour change; the blue colour is retained (no violet / purple colour forms). |
Protein is absent. |
| (iii) A crushed portion of D smeared on filter paper and left for about 5 minutes. |
The paper is stained orange (no permanent translucent grease mark). |
Fat (oil) is absent. |
Conclusion: Specimen D (carrot) contains starch but no detectable protein or fat, which agrees with the entry in the table for D that its main stored material is water, starch and sugar.
Identification of the specimens: The four specimens are all organs of vegetative (perennating) propagation. Specimen A is the stem of a cactus, specimen B is an onion bulb, specimen C is a ginger rhizome, and specimen D is a carrot.
(a) Completed table
| Specimen |
Part modified to form specimen |
Mode of propagation |
Stored material |
| A |
Stem |
Stem (stem cutting) |
Water / carbohydrate |
| B |
Shoot (fleshy leaf bases) |
Bulb |
Water / sucrose |
| C |
Stem |
Rhizome |
Water / starch |
| D |
Root |
Root tuber |
Water / starch / sugar |
(b) Four observable differences between specimen A (cactus stem) and specimen C (ginger rhizome)
| Specimen A (Stem of cactus) |
Specimen C (Rhizome of ginger) |
| Green in colour |
Brown / grey-yellow in colour |
| Flattened in shape |
Cylindrical in shape |
| Leaves reduced to spines |
Leaves reduced to scales |
| Nodes and internodes not distinct |
Nodes and internodes distinct |
| Adventitious roots absent |
Adventitious roots present |
| Terminal buds absent |
Terminal buds present |
(Any four of the paired differences above are acceptable.)
(c) Test for food substances in specimen D (carrot)
| Test |
Observation |
Inference |
| (i) A portion of D on a white tile + 2 drops of iodine solution. |
A blue-black colour is formed. |
Starch is present. |
| (ii) A portion of D + 1 ml distilled water, shake; add a few drops of sodium hydroxide (NaOH) solution, shake; then add a few drops of 1% copper(II) sulphate solution. |
No colour change; the blue colour is retained (no violet / purple colour forms). |
Protein is absent. |
| (iii) A crushed portion of D smeared on filter paper and left for about 5 minutes. |
The paper is stained orange (no permanent translucent grease mark). |
Fat (oil) is absent. |
Conclusion: Specimen D (carrot) contains starch but no detectable protein or fat, which agrees with the entry in the table for D that its main stored material is water, starch and sugar.
