Bachelor of Science (BSc) — Environmental Science — Academic Support

Welcome to Bachelor of Science (BSc) — Environmental Science — Academic Support. We will study Ecosystem Structure and Function: Productivity, Energy Flow, Food Webs and Ecological Pyramids, work through an example, and practise using the course's learning material. 3-year bachelor’s route / 4-year honours or research route, where offered. Year-wise / professional-phase study plans, original foundation workshops, answered practice and available protected LMS readings. Sign in and use the study header to open your authorised course. Select this published lesson. Start Course Tutor with Auto audio on: it teaches continuously, answers a typed question, then resumes. Gross primary productivity (GPP) is the total rate of photosynthesis. Net primary productivity (NPP) is what remains after the producers' own respiration (R): NPP = GPP − R. NPP is the energy available to herbivores and decomposers. Secondary productivity is the rate of new biomass formation by consumers. Problem 1 — productivity and transfer. In a grassland, GPP is 20,000 kJ m⁻ squared yr⁻¹ and plant respiration is 8,000 kJ m⁻ squared yr⁻¹. Assuming 10 per cent transfer at each step, estimate the energy reaching herbivores and then carnivores. NPP = 20,000 − 8,000 = 12,000 kJ m⁻ squared yr⁻¹. Herbivores: 10 per cent of 12,000 = 1,200 kJ m⁻ squared yr⁻¹. Carnivores: 10 per cent of 1,200 = 120 kJ m⁻ squared yr⁻¹. Check: 12,000 times 0.1 times 0.1 = 120. Answer: 1,200 and 120 kJ m⁻ squared yr⁻¹. Which mistake would change the reasoning in this example? 1. Writing that all pyramids can be inverted. Correction: numbers and biomass can be inverted; energy never can. 2. Confusing GPP and NPP. Correction: only NPP is available to the next level; GPP includes energy the plant burns in its own respiration. Ask Course Tutor: please explain this step from the example. NPP = 20,000 − 8,000 = 12,000 kJ m⁻ squared yr⁻¹. Herbivores: 10 per cent of 12,000 = 1,200 kJ m⁻ squared yr⁻¹. Why does it follow? Add what you tried, so the explanation addresses your difficulty. Now try the source practice. If NPP is 8,000 kJ m⁻ squared yr⁻¹ and transfer efficiency is 10 per cent, how much energy reaches the tertiary consumers? Pause before the answer. The source answer is: 8,000 times 0.1 times 0.1 times 0.1 = 8 kJ m⁻ squared yr⁻¹. Compare your reasoning as well as the result. If your response differs, return to the worked example and identify the step that needs correction. Explain the key idea in your own words, revisit any mistaken step, then continue to the next lesson. Use Stop to end Course Tutor when you finish.