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Lesson 4:
Feeding
Relationships

Follow the movement of energy through food chains, food webs, trophic levels, ecological pyramids, and Caribbean feeding examples.

Watch Lesson Take Quiz
Section A
Objectives 3.1-3.5
Quiz 25 marks

The Energy Journey

Watch how energy moves from producers to consumers and why food chains rarely extend beyond four or five trophic levels.

Study Guide Summary

Key feeding relationship ideas for CSEC Biology SO 3.1 to 3.5.

Food Chains

A food chain shows feeding relationships. Arrows point from food to consumer because they show energy flow.

Trophic Levels

Each feeding position is a trophic level: producer, primary consumer, secondary consumer, and tertiary consumer.

Consumers

Herbivores eat plants, carnivores eat animals, and omnivores feed at more than one trophic level.

Food Webs

Food webs show interconnected food chains, making ecosystems more flexible when one population changes.

Energy Transfer

Only about 10% of energy entering a consumer level is usually passed to the next level.

Ecological Pyramids

Pyramids of numbers, biomass, and energy represent population size, biological material, and energy transfer.

Lesson Flashcards

Use these as quick oral checks before attempting the 25-mark quiz.

Vocabulary and Trophic Levels

A diagram showing feeding relationships where arrows represent energy flow from one organism to the next.
The specific feeding level an organism occupies in a food chain.
Producers make food using sunlight. Consumers feed on organisms. Herbivores eat plants, carnivores eat animals, and omnivores eat both.

Energy Flow

They show the direction of food and energy flow, pointing away from the food and toward the consumer.
About 10%. Energy is lost as heat, movement, respiration, egested material, and excreted waste.
So much energy is lost at each level that there is too little left to support many top predators after four or five trophic levels.

Dominica Forest Food Web

Grass and forest trees, including their leaves and fruits.
Bush-crickets, caterpillars, and common fruit bats.
Dominican anole and mangrove cuckoo are secondary consumers. Antilles racer and barn owl are tertiary consumers.

Ecological Pyramids and Roles

Numbers show estimated populations, biomass shows biological material, and energy shows energy flowing between trophic levels.
Bacteria and fungi that secrete enzymes onto dead material and recycle carbon by releasing carbon dioxide.
The use of predators or parasites of pest species to reduce crop damage.

Self-Assessment Quiz

Answer all sections. The food-chain section accepts valid chains from the Dominica forest data.

CSEC Biology SO 3.1-3.5 Total marks: 25
1. Which is the best definition for a herbivore?

2. In an ecosystem, producers are typically:

3. The different feeding levels in a food chain are known as:

4. In a diagram of a food chain, what do arrows represent?

5. Mangrove trees -> moth caterpillars -> Anolis lizard -> pearly-eyed thrasher. What is the Anolis lizard?

6. What is the primary source of energy for almost all food chains?

7. Approximately what percentage of energy entering a consumer trophic level is transferred to the next level?

8. Decomposers play a vital role in the carbon cycle by:

9. A broad-winged hawk feeding at the top of a food chain is classified as a:

10. What is the main difference between a food chain and a food web?

Section B: Food web analysis

Build a valid four-organism food chain from the Dominica forest data. Choose organisms in the order energy flows.

Select the organisms at the first trophic level.

Section C: Energy flow and pyramids

Select two ways energy is lost from a trophic level.

Select two reasons there are usually fewer organisms at the top of a pyramid of numbers.