2.2Ecology
Energy flow — EST 2 Biology Revision Notes & Topical Questions
5 min read 8 parts Lesson 2 of 8 2 quizzes
Energy flow EST Biology revision notes.LESSON SUMMARYCore summary: Energy enters most ecosystems as light, is captured by producers, and moves through trophic levels to consumers.
- Decomposer
- Ecological pyramid
- Energy flow EST Biology: what to do next
- Exam focus
- Keywords the mark scheme looks for in this lesson
- Command words
Section 1 of 8Overview
Core summary Energy enters most ecosystems as light, is captured by producers, and moves through trophic levels to consumers. At each transfer, much energy is lost through respiration, heat, movement, waste and uneaten material.
Exam focus use a pyramid of energy to explain why higher trophic levels contain less available energy.
Section 2 of 8Key words
Section 3 of 8Comparison table
| Level | Organism type | Example | Energy available | Energy lost as | Pyramid width |
|---|---|---|---|---|---|
| 1 | Producer | Grass | 10 000 kJ | Respiration, heat | Widest |
| 2 | Primary consumer | Grasshopper | 1 000 kJ | Heat, waste | — |
| 3 | Secondary consumer | Frog | 100 kJ | Heat, waste | — |
| 4 | Tertiary consumer | Snake | 10 kJ | Heat, waste | — |
| 5 | Quaternary | Hawk | 1 kJ | — | Narrowest |
Section 4 of 8Pathway
- Sun
- Producer
- Primary consumer
- Secondary consumer
- Tertiary consumer
Section 5 of 8Key facts
Section 6 of 8Exam technique
- Producer · Consumer · Trophic level · 10% rule · Food web · Decomposer · Biomass · Ecological pyramid
- Learn each definition in the Key words tab exactly; a missing keyword in a definition usually loses the mark.
- Identify / Describe (FRQ)
- A short, specific statement; describing requires relevant characteristics, not a single word.
- Explain / Justify (FRQ)
- Give the cause-and-effect reasoning or evidence; a restated fact does not score.
- Calculate
- Show setup, substitution and the answer with units.
- Predict
- State the expected outcome; add a reason only if asked to justify.
- MCQ technique
- Read every option;
- eliminate distractors that are true statements but do not answer the question;
- watch for NOT/EXCEPT.
- Read every option;
- Answer exactly what is asked;
- extra correct material does not earn credit, and contradictory statements can cancel credit (AP FRQ).
- Use precise vocabulary (e.g. “active site”, “concentration gradient”, “allele”), never “it/stuff/things”.
- Show units and working in calculations.
- In MCQs, predict the answer before reading the options, then eliminate.
Section 7 of 8Practice questions
Q1. Which statement best describes Biomass?
Show answer
Mass of living material.
Q2. Complete the statement: About ______ of energy passes to the next level.
- Trophic level
- 10%
- Decomposer
- Biomass
Show answer
10%
Q3. Which key term matches this description: "Diagram of numbers, biomass or energy per level."
- Ecological pyramid
- Biomass
- Producer
- Decomposer
Show answer
Ecological pyramid
Q4. Which statement best describes Producer?
Show answer
Makes its own food (autotroph).
Section 8 of 8Keep going
Energy flow EST Biology: what to do next
These Energy flow EST Biology notes covered the key ideas, worked examples and exam technique for this topic. Check your Energy flow EST Biology understanding with the practice questions below, then reread any Energy flow EST Biology point you were unsure about before moving on.
Marked practiceQuizzes for this lesson
Last updated:
\n