(a)(i) What is sewage?
(ii) State five effects of releasing untreated sewage into a stagnant water body.
(b) Explain surface terracing as a soil conservation method.
(c) Explain the term adaptation.
(d) Explain two ways each by which the following organisms adapt to their habitats:
(i) hydrophytes
(ii) xerophytes.
Explanation
(i) Sewage : Waste matter/ feaces, urine, waste water from animals/industrial/domestic sources; that is dissolved/ suspended in water.
(ii) Effects of releasing untreated sewage into a stagnant water body;
- Spread of water-borne diseases/correctly named diseases/microbes/pathogens
- May be toxic/poisonous to aquatic life/organisms
- Makes water unfit for consumption/use
- Increased decomposition
- Increased concentration of nutrients
- Rapid growth of algae/aquatic plants/algal bloom/eutrophication
- Depletion of oxygen
- Suffocation/death of aquatic animals
- Generates offensive odour/air pollution
- Nutrient/nitrate/phosphate enrichment/accumulation in a water body; as a result of breakdown by bacteria.
(b) Surface terracing as a soil conservation method :
A method of controlling erosion on a gentle/steep slope of hill; flat horizontal areas are constructed on which crops are cultivated; following the contour; steps/walls are built along the contous; plughing is also done along the contours; reduces the speed of water running down the slopes.
(c) Adaptation : Is the possession of the characteristic/trait/behaviour/structure/feature; that evolved over a period of time; enable an organism to survive and reproduce; in response to changes in the environment/habitat.
(d) Adaptation of;
(i) Hydrophytes
- Some hydrophytes lack/have reduced roots/root hairs/root caps
- do not need firm anchorage in water/wetland
- presence of large air space parenchyma in roots/leaves; provide support for buoyancy
- Presence of hairs on the leaves; to prevent blockage of the stomata
- stomatal pores; occur only at the upper epidermis of the leaves to aid transpiration/loss of water
- numerous adventitious roots and root hairs; aid the absorption of water/mineral salts
- small size of the plant; for buoyancy/floating in water
- waxy upper surface of the leaf; to prevent clogging of the leaf by water
- long petiole/leaf stalk to support/ expose the broad lamina for photosynthesis
- long flower stalk/pedicel; to expose flower for pollination/ pollinating agents
- presence of breathing roots/pneumatophores; for breathing/gaseous exchange.
Xerophytes
- possession of thick succulent leaves/stem; for storing water
- reduction of leaves to spines; to reduce water loss/rate of transpiration
- thick waxy cuticle on epidermis; to reduce water-loss/transpiration
- possession of long tap root system; tp obtain water from great depth of soil
- presence of sunken stomata; to reduce water loss
- reduced number of stomata; to prevent excessive water loss
- possession of multiple epidermal layers; for water conservation/to reduce water loss.