Organisms & Their Environment
Food chains and energy flow, the carbon and nitrogen cycles, populations, and human impact, the section where the marks are in the sequence of events.
What this lesson covers
Organisms & Their Environment is a 8-part O Level Biology lesson. Each part makes one point and then hands over to the next, so it can be read in a sitting or picked up again at the part you stopped on. It defines the idea in plain words before using it, works through an example step by step, breaks the topic into its parts and compares them, shows where it is used outside the textbook, names the mistakes that cost marks in an exam, ends with a recap of what to remember.
How it begins
A food chain shows the flow of energy from one organism to the next. The arrows show the direction energy flows, so they point from the eaten to the eater. Drawing them backwards is an easy mark to lose. Producers (usually green plants) make their own food by photosynthesis and are the start of almost every chain; the ultimate source of the energy is the Sun.
The 8 parts
- Feeding relationships and the vocabulary
- Energy flow, and why chains are short
- The carbon and nitrogen cycles
- Populations, and the S-shaped curve
- Human impact: the sequences worth memorising
- Where marks go
- What to remember
- Watch one worked through
Practise Organisms & Their Environment
Everything on QuizByt for O Level Biology that goes with this lesson: read it first, then test yourself while it is fresh.
🧠 5 quizzes on Organisms & Their Environment (2 easy, 2 medium, 1 hard)
Work up from easy to hard: the hard quiz asks the O Level exam-style questions on Organisms & Their Environment.
🖨️ Printable worksheet
Organisms & Their Environment on paper for O Level, with room to write the working out. Preview the first page free.
🎮 Games for O Level Biology
Memory and reasoning games at the right level for O Level. Passing a quiz on Organisms & Their Environment earns the credits that open them.
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