(a) Cabbages are crop plants.
Fig. 6.1 shows an area where the forest has been removed to create space for a monoculture of cabbage plants.
(i) Describe reasons for habitat destruction, other than crop production.
(ii) Describe the advantages of growing crops such as cabbages as a large‑scale monoculture.
(b) Habitat destruction can cause species extinction. State two ways that species can be conserved, other than protection of their habitat.
(c) Four islands, A, B, C and D, were surveyed to identify the different types of crop plant monocultures present. The survey identifies the percentage of each type of monoculture on each island. Fig. 6.2 shows the results of the survey.
Identify the island or islands from Fig. 6.2 that: have the greatest number of different types of monocultures ………………………. have the greatest percentage of crop 2 monocultures ………………………. have more than 50% crop 3 monocultures. ………….. and ………….. .
(d) One effect of deforestation and monocultures is a reduction in biodiversity. State what is meant by the term biodiversity.
(e) Crop 3 is a type of tree that can be used for firewood. Suggest how this resource can be managed sustainably.
▶️ Answer/Explanation
Ans:
(a)(i) Habitat destruction occurs due to urbanization, infrastructure development, mining, pollution, or climate change. These activities reduce natural habitats, leading to biodiversity loss.
(a)(ii) Monoculture advantages include higher yield, cost efficiency, easier harvesting, and uniform application of fertilizers/pesticides, making large-scale farming more profitable.
(b) Species conservation methods include captive breeding, seed banks, anti-poaching laws, and reintroduction programs to prevent extinction.
(c) Island A has the most monoculture types. Island A leads in Crop 2. Islands B and D have >50% Crop 3 monocultures.
(d) Biodiversity refers to the variety of species in an ecosystem, crucial for ecological balance and resilience.
(e) Sustainable firewood management involves replanting trees and regulating logging to prevent deforestation.
Final Answers:
(a)(i) Urbanization, mining, pollution, etc. (any three valid reasons).
(a)(ii) Higher yield, cost efficiency, easier harvesting.
(b) Captive breeding, anti-poaching laws.
(c) A ; A ; B and D.
(d) Variety of species in an ecosystem.
(e) Replant trees and regulate logging.
Fig. 7.1 shows how some uses of land have changed from the year 1500 to the year 2000 in one country.
(a) Using the data in Fig. 7.1:
(i) Identify the years when there was the largest increase in the percentage of land used for farming.
(ii) State the trend for the percentage of land used for housing.
(iii) State the year when the percentage of land used for forests and wild plants was equal to the percentage of land used for farming.
(b) Deforestation is one of the consequences of using land for farming.
Outline the undesirable effects of deforestation.
(c) State one way humans can damage aquatic environments.
▶️ Answer/Explanation
(a) (i) From 1800 to 1900
The largest increase in farming land occurs between these years, as seen in the steepest rise in the graph.
(a) (ii) The percentage of land used for housing increases.
The graph shows a consistent upward trend in housing land use over time.
(a) (iii) 1970
The graph intersects at this year, indicating equal percentages for forests/wild plants and farming.
(b) Undesirable effects of deforestation include:
– Loss of biodiversity and habitat destruction.
– Soil erosion and increased flooding.
– Higher carbon dioxide levels in the atmosphere.
(c) One way humans damage aquatic environments:
– Pollution (e.g., sewage, plastics) or overharvesting of aquatic species.