Question 1
- The diagram below is an illustration of an incomplete drawing of a short-horned grasshopper. Study it and answer questions 1 (a) to 1 (e).
(a) (i) Name the parts labeled I, II, III and IV. [2 marks]
(ii) State two ways by which the part labeled III is adapted to its function. [4marks]
(b) Complete and label the diagram with the following structures:
(i) compound eye;
(ii) hind leg;
(iii) mouthparts;
(iv) antennae. [7 marks]
(c) State two ways by which the organism is of economic importance to:
(i) its ecosystem;
(ii) humans. [4 marks]
(d) Classify the organism into:
(i) Phylum;
(ii) Class. [2 marks]
(e) Give three reasons each for the answers in 1 (d) (i) and 1 (d) (ii)
(i) Phylum;
(ii) Class. [6 marks]
Observation
Some candidates could name the labelled parts but lost marks to poor spellings of the names.
The candidates that stated the adaptation of the part labelled III could not state the feature with its function. Some only stated the function which made them lose one mark.
Some candidates displayed their ignorance of the structure of a grasshopper by not placing the listed structures in their appropriate positions on the incomplete grasshopper in the diagram.
Majority of the candidates were able to state the economic importance of grasshopper to its ecosystem and humans.
Some candidates could not classify the grasshopper into its phylum and class, neither could they give the reason for the classification. A few that could, lost marks to poor spellings.
The expected answers are:
- (a) (i) Name of labelled parts
I. Elytron/forewing/wing;
II. Abdomen/abdominal segment;
III. (Walking) leg;
IV. Pronotum/thorax/scutellum.
(ii) Adaptation of the part labelled III to its function
- It is short; for safe landing;
- Presence of claws at its tips; to grip vegetation/for firm grip/for stability;
- Claws; for crawling/movement
Note: Feature of the structure and function must correspond to score 2 marks;
Feature alone can score 1 mark;
Function alone does not score.
(b) Complete drawing of the illustrated drawing
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Details
Compound eye (big 1/3 of the head) - (CE)
Hind leg (large and long) - (LL);
Mouthparts (properly shown) - (MP);
Antennae (Short and segmented) – (AN).
Note: 1 mark for correct position of each part.
Quality
Clarity of lines (CL)
Ruled guideline (RG)
Horizontal labels (HL)
(c) Ways by which the organism is of importance to
(i) its ecosystem
- Destroys vegetation;
- Breathes out carbon dioxide which plants use for photosynthesis;
- Serves as food for other organisms;
- Causes discomfort/nuisance.
(ii) humans
- Serves as food/feeds for poultry;
- Destroys crops;
- Serves as specimen for scientific research;
- Reduces crop yield;
- Provides income.
Phylum
Arthropoda
(ii) Class
Insecta
Reasons for classification
(i) Phylum
- Jointed appendages;
- Chitinous exoskeleton covers body;
- Body bilaterally symmetrical;
- Body metamerically segmented
(ii) Class
- Body is divided into head, thorax and abdomen/three body divisions;
- Thorax bears three pairs of legs;
- A pair of wings;
- A pair of compound eyes;
- A pair of antennae.