Question 1
The diagram below is an illustration of a split castor oil seed. Study it and answer questions1(a) to 1(d).
(a) (i) Name the parts labelled I to VI. [3 marks]
(ii) Name the type of seed illustrated with respect to the part labelled II.
[1 mark]
(b) State one function each of the parts labelled b Ito VI. [6 marks]
(c) Name two food substances present in the structure labelled II. [2 marks]
(d) The following materials were provided in the laboratory: sodium hydroxide
solution, filter paper, copper (II) sulphate solution and iodine solution.
[8 marks]
(e) What is the fate of each of the food substances named in 1(c) during germination
of the seed? [2 marks]
(f) State three conditions necessary for the germination of the seed. [3 marks]
Observation
Some candidates could not name the labelled parts of the diagrams correctly.Some could also not state the functions performed by each of the labelled parts. They could not also name the type of seed illustrated and state the fate of starch, oil and protein stored in the part labelled II.
Many candidates were able to state the condition necessary for germination but lost marks to wrong spellings.
The expected answers are:
(a)(i) Name of Labelled Part
I: radicle; IV: cotyledons;
II: endosperm; V: vein;
III:testa; VI: caruncle/aril
(ii) Type of Seed with Respect to II
Endospermous
(b) Function of Labelled Parts
I: grows to form the root;
II: stores food;
III:protects seed;
IV: conducts food to growing parts/stores food;
V: conducts food;
VI: absorbs water.
(c) Food Substances Present in II
starch;
oil;
protein.
(d) Procedure for Food Test in the Laboratory
Starch
Add a few drops of iodine solution; to a piece of the labelled II/
endosperm; a blue black colouration is observed; indicating the presence of starch.
Oil
Rub a piece of the part labelled II/endosperm; on the filter paper; the spot
becomes translucent; indicating the presence of oil.
Protein
Crush a piece of the part labelled II/endosperm; place test tube and add a few drops of water; add equal volume of sodium hydroxide solution and 1% copper(II) sulphate solution drop by drop into the test tube shaking after each drop; a violet/purple coloration is observed; indicating the presence of protein.
(e) Fate of Food Substance
Starch
Broken down to simple sugars; and used up in respiration; to produce energy for
Germination.
Oil
Broken down in respiration; to produce energy for germination.
Protein
Used to form structures at growing parts/used for growth of radicle and plumule.
(f) Conditions for Germination
- viable seed;
- oxygen/air;
- moisture/water;