Biotic vs abiotic, niche vs habitat, population vs community vs species — and how soil, water and climate affect living things.
6 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
A crab and a mangrove tree share the same address. So why don’t they compete?
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
Biotic = living factors (predators, competitors, disease). Abiotic = non-living (light, temperature, water, pH, salinity, wind, soil).
Habitat = where an organism lives. Niche = its role: feeding, activity pattern, interactions.
Population = one species in an area. Community = all species in an area.
Species = organisms able to interbreed to give fertile offspring. Population = members of one species in one place at one time.
A community interacting with its abiotic environment, e.g. a coral reef, mangrove, pond.
Supplies water, minerals, air for root respiration and anchorage. pH and humus content affect plant growth.
Temperature (enzymes), light (photosynthesis), rainfall and humidity (water supply, vegetation type).
The kind of support a teacher gives after the lesson: worked examples to attempt first, a board illustration, key terms, common misconceptions and memory aids.
Try it in your notebook first, then reveal the solution one step at a time.
| Distance from trunk (m) | 0 | 2 | 4 | 6 | 8 |
|---|---|---|---|---|---|
| Light intensity (lux) | 800 | 1500 | 3200 | 5600 | 8000 |
| Grass plants per m² | 2 | 5 | 12 | 25 | 31 |
Try it in your notebook first, then reveal the solution one step at a time.
Each level includes the one before it. Only the ecosystem includes the non-living (abiotic) environment.
Habitat = Address, Niche = Job. “Where do you live? What do you do?”
In Caribbean mangroves, abiotic factors — salinity and how long the ground is flooded by the tide — decide where each mangrove species grows. Red mangroves, with their prop roots, usually grow at the water’s edge; black and white mangroves grow further inland.
Record the temperature in a sunny spot and a shady spot at the same time each day for a week. Which organisms do you find in each spot?
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better.
Write full answers, then reveal the mark scheme and tick the points you earned (12 marks in total). Your answers are saved on this device.
Question 1 [6 marks]
A biologist recorded soil moisture (low 1%, normal 15%, high 45% by volume) and CO₂ concentration (390, 400, 410 ppm) in a tropical forest over one year.
(a) Name TWO abiotic factors, other than soil moisture and CO₂, that affect living organisms. [2]
(b) Explain what would happen to the plants if soil moisture stayed at 62% for three weeks. [2]
(c) Explain the likely effect if CO₂ stayed above 410 ppm for three weeks. [2]
Question 2 [6 marks]
Answer the following about abiotic factors.
(a) Define the term “abiotic factor”. [1]
(b) Distinguish between a population and a community. [2]
(c) List THREE human activities that may disrupt abiotic factors in an ecosystem. [3]
Find these in your own past-paper booklets for extra timed practice. The practice above is adapted from them.