Question 5
(a)
Complete the table below.
Organism |
Mode of feeding |
Feature of mouthpart that adapts |
Adult mosquito |
temperature is higher; |
|
Weevil |
||
Cockroach |
(b) List five parts of the alimentary canal of an earthworm.
[5 marks]
(c) State six ways by which water could be polluted by agricultural practices.
[6 marks]
(d) Describe briefly the life cycle of a housefly.
[5 marks]
(e) Make a diagram, 6 cm – 8 cm long of the hypogeal germination in a mature maize seedling and label fully.
[8 marks]
Observation
This question was compulsory.
Question (a) was not properly answered as most candidates could state the feature of the mouthparts of the listed organisms.
In (b), Some candidates could list the parts of the alimentary canal of an earthworm but lost marks to spelling mistake.
In (c), some candidates performed well in this question.
In (d), some candidates could not properly describe the lifecycle of a housefly, while others lost marks to the spelling of technical terms.
In (e), many candidates got the drawing but lost marks to other details and quality of diagram
The expected answers are:
- Table
Organism |
Mode of feeding |
Feature of mouthpart that adapts |
Adult mosquito |
Fluid feeding/piercing/sucking |
Proboscis/modified long mandible and maxillaeg |
Weevil |
Chewing/boring |
Possession of pointed short and strong rostrum |
Cockroach |
Biting/chewing |
Well developed mandibles/strong sharp mandibles |
- Mouth
- Pharynx
- Oesophagus/gullet
- Crop;
- Gizzard
- Intestine;
- Anus.
Note: Spellings must be correct to score.
(c) Ways by which water could be polluted by agricultural practices
- Farmers add excess fertilizers/organic material to soil which may cause water pollution
- The inorganic/artificial fertilizers that contain high concentrations of nitrates and phosphates, dissolves in rain water and washed into nearby streams and rivers
- Nitrates and phosphates accelerate the growth of algae/eutrophication
- The death/decay of algae in rivers and streams increase the population of bacteria rapidly
- And cause oxygen level to decrease drastically
- Killing aquatic organisms;
- Use of chemicals/dynamite for fishing which pollutes water
- Dumping of cleared vegetation on water bodies
- Slash-burn methods of farming which might wash ash to nearby rivers/water bodies
- Pesticides/insecticides also sprayed on crops are usually non-biodegradable
- They are washed into nearby rivers/streams/water bodies
- Accumulate in the bodies of aquatic organisms;
- And are passed along the food chain
- The concentration of pesticides/insecticides can reach toxic level in the bodies of the final consumers in the higher trophic levels is causing these organisms to die.
(d) Life cycle of a Housefly
- The female housefly lays eggs on decomposing matter/rubbish
- The eggs hatch into larvae/maggot
- In a few hours;
- They crawl unto food
- Which if solid will be digested by enzymes to liquid
- The larvae have twelve segments on the body
- The body then contracts
- The skin hardens and turns brown to enclose the pupa
- After about four days, the pupa changes into the adult/imago
- Inside the puparium/brown skin cover
- The adult fly then emerges
- And flies away.
(e)
Diagram of a mature maize seedling
Title (Tl)
Quality (Q)
Clarity of lines (CL)
Size (Sz) (6-8cm)
Neatness of labels (NL)
Details (D)
Cotyledon below the ground (CG)
Coleoptile/Plumule sheath shown (CS)
Label (L)
Foliage leaves; coleoptile; cotyledon/remnant of fruit; roots/adventitious roots/fibrous roots; root hairs.