5(a)(i) Differences between the alimentary canals of earthworm and cockroach
| Earthworm | Cockroach |
|---|
| The alimentary canal is almost straight, extending from the anterior mouth to the posterior anus. | The alimentary canal is coiled and is differentiated into foregut, midgut and hindgut. |
| It has no gastric caeca. | It has gastric caeca at the junction of the foregut and midgut, which secrete digestive enzymes. |
| Its intestine has a typhlosole, which increases the surface area for absorption. | Its midgut has no typhlosole; instead, it has numerous gastric caeca. |
| No Malpighian tubules open into its alimentary canal. | Malpighian tubules open into the alimentary canal at the junction of the midgut and hindgut. |
5(a)(ii) Similarities between the alimentary canals of earthworm and cockroach
- Each has a complete alimentary canal with a mouth and an anus.
- Each has a pharynx, oesophagus, crop, gizzard and intestine.
- In each, food is digested, absorbed through the gut wall and undigested materials are egested through the anus.
5(b)(i) Name of biological cycle
The cycle is the carbon cycle.
Roles of plants and animals in the carbon cycle
- Green plants remove carbon dioxide from the atmosphere during photosynthesis and convert it into organic food substances.
- Animals obtain carbon compounds by feeding on plants or on other animals.
- Plants and animals release carbon dioxide back into the atmosphere during respiration. When they die, decomposers break down their remains and return carbon compounds to the environment.
5(b)(ii) Processes occurring at X, Y and Z
| Label | Process |
|---|
| X | Photosynthesis |
| Y | Respiration |
| Z | Decay or decomposition |
5(c) Completed table
| Organ associated with excretion in humans | Three diseases that affect the organ |
|---|
| Kidney | - Nephritis
- Kidney stones
- Renal failure
|
5(d)(i) Decay of organic matter is the breakdown of dead plants, dead animals and their wastes into simpler substances.
5(d)(ii) The two groups of organisms that cause decay are bacteria and fungi.
5(d)(iii) Moisture or water is one factor that promotes decay.
5(d)(iv) The biological cycle involving decay is the carbon cycle.
5(e) Carnivorous plants are mainly autotrophic because they manufacture carbohydrates by photosynthesis. However, they trap small animals, especially insects, using modified leaves such as pitchers or snap traps. Enzymes digest the trapped animals, and the plants absorb mineral salts, especially nitrogen compounds, from them. This enables the plants to survive in nitrogen-deficient soils.
