(a)(1) Explain briefly chemosynthesis as a mode of nutrition.
(ii) Give two examples of organism that carry out chemosynthesis.
(b) List three gases in the atmosphere with their percentage composition.
| Gases in the atmosphere | Percentage composition |
(c) (i) State four characteristics of a salt marsh habitat.
(ii) Explain briefly how plants are modified for anchorage in a salt marsh habitat.
(d) (i) List four bacterial disease associated with poor food hygiene.
(ii) State three effects of poor food hygiene.
(e) A person was involved in a car accident and became unconscious due to excessive blood loss. Explain briefly how the blood lost could be restored.
(f) State three differences between tillage and bush burning as farming practices.
| Tillage | Bush burning |
Explanation
(a) (i) Chemosynthesis;
- The process by which some organisms manufacture their food
- By converting carbon molecules into organic substances
- Using the oxidation of inorganic substances/ hydrogen sulphide/ammonia/methane
- As a source of energy without the use of sun light/solar energy.
(ii) Examples of organisms that carry out chemosynthesis;
- Sulphur bacteria
- Nitrosomonas
- Nitrobacter
- Blue-green algae
- Nitrococcus
(b) (i) Percentage composition of gases in the atmosphere
| S/N | Gases in the atmosphere | % composition |
| 1 | Oxygen | 205 - 21.5 |
| 2 | Nitrogen | 78- 79 |
| 3 | Noble gases / Argon | 0.9 - 1.0 |
| 4 | Carbon dioxide | .03 - 0.05 |
(c) (i) Characteristics of salt marsh habitat
- Presence of low oxygen level;
- High salinity
- Soft muddy environment
- Presence of changing water levels
- Flat lowland
- Swampy/water-logged
- Low light'penetration
(i) Modification of plants to salt marsh habitat
Plants grow long/have numerous roots; to hold to the substratum; possess stilt roots for anchorage
(d) (i) Bacterial diseases associated with poor food hygiene
- (Staphylococcal) Food poisoning
- Dysentery; Cholera
- Hepatitis
- Typhoid
- Gastritis
- Botulism
- Tuberculosis
- Any correctly named disease.
(ii) Effects of bad food hygiene
- May lead to intestinal ulcer
- May lead to serious food poisoning
- Sickness/discomfort
- Frequent stooling/running stomach/diarrhoea
- Loss in economic value/loss in food value
- Death.
(e) Restoring blood loss of an accident victim after a car accident
- The victim must first be rushed to the hospital
- Where the blood sample will be taken
- For agglutination test
- To know the blood group
- Then the compatible blood is transferred to the victim.
(f) Differences between tillage and bush burning.
| Tillage | Bush burning |
| Loosens the soil | compacts the soil |
| Aerates the soil | leads to poor aeration of the soil |
| Mixes organic matter with soil/improves soil nutrients | Depletes / destroys soil nutrients / leaching |
| Enhances the activities of micro organism | Micro fauna / soil organisms are killed |
| Does not lead to soil / air pollution | leads to air / soil pollution |