Question 1: Define 'biodiversity' and give an example from a tropical rainforest ecosystem.

Answer: Biodiversity refers to the variety of plant and animal life in a particular habitat; for example, the Amazon Rainforest hosts over 390 billion individual trees and countless species of animals.

Question 2: What is 'primary productivity' in an ecosystem?

Answer: Primary productivity is the rate at which plants and algae convert sunlight into chemical energy via photosynthesis.

Question 3: Explain the term 'trophic levels' with an example.

Answer: Trophic levels describe the positions of organisms in a food chain; for example, plants are at the first trophic level, herbivores at the second, and carnivores at the third.

Question 4: Name the two main types of terrestrial ecosystems.

Answer: Grassland and forest

Question 5: What is an 'ecosystem service'? Provide one example.

Answer: An ecosystem service is a benefit humans receive from ecosystems; for example, pollination of crops by bees.

Question 1: Identify three characteristics that define a desert ecosystem.

Answer: Low rainfall, extreme temperature variations, sparse vegetation

Question 2: Name the three main types of aquatic ecosystems.

Answer: Freshwater, marine, estuarine

Question 3: Describe the role of producers in an ecosystem.

Answer: Producers, mainly plants and algae, convert sunlight into energy through photosynthesis and form the base of the food chain.

Question 4: What is the main difference between a tropical rainforest and a tundra?

Answer: Tropical rainforests have high temperatures and rainfall with dense vegetation, while tundras are cold, dry, and have permafrost with limited vegetation.

Question 1: Based on the case study of the Amazon Rainforest, analyze how deforestation has impacted biodiversity and climate regulation.

Answer: Deforestation in the Amazon has led to a significant loss of biodiversity, with many species losing their habitats. It also reduces the forest's ability to act as a carbon sink, contributing to increased greenhouse gases and climate change. The removal of trees disrupts local water cycles and increases soil erosion.

Question 2: In the Sahara Desert case, explain how adaptations of flora and fauna enable survival in such an extreme environment.

Answer: Plants like cacti have thick, fleshy stems to store water and spines to reduce water loss. Animals such as foxes and lizards are nocturnal to avoid daytime heat. These adaptations help conserve water and regulate body temperature in the harsh desert climate.

Question 1: Analyse the causes of desertification in the Sahel region.

Answer: Desertification in the Sahel is driven by overgrazing, deforestation, climate change leading to reduced rainfall, and poor land management practices. These factors lead to soil degradation, loss of vegetation cover, and expansion of desert areas.

Question 2: Explain why coral reef ecosystems are vulnerable to climate change.

Answer: Coral reefs are sensitive to temperature increases, leading to coral bleaching. Ocean acidification caused by increased CO2 levels weakens coral skeletons, and rising sea levels reduce sunlight penetration, threatening reef survival.

Question 3: Evaluate the impact of invasive species on native ecosystems, using examples such as the cane toad in Australia.

Answer: Invasive species like the cane toad disrupt native food chains, outcompete indigenous species for resources, and introduce new diseases. The cane toad's proliferation in Australia has led to declines in native predators and altered ecological balances.

Question 1: To what extent are current conservation strategies effective in protecting tropical rainforests like the Amazon?

Answer: Conservation strategies such as protected areas, sustainable logging, and international agreements have had varying success. While some areas have seen reduced deforestation, illegal activities and economic pressures continue to threaten the rainforest. Overall, these strategies are beneficial but require stronger enforcement and community involvement to be fully effective.

Question 2: Evaluate the effectiveness of ecological restoration projects in degraded ecosystems such as the Sahel.

Answer: Restoration projects like reforestation and sustainable land management have improved soil quality and increased vegetation cover in some areas. However, challenges such as climate variability and lack of resources limit their widespread success. While beneficial, these projects need long-term commitment and integrated approaches to ensure resilience.