Name: INSHRAH AZIZ
SEAT NO: B23120006026
BS MATHEMATICS 2ND YEAR
“FOOD CHAIN”
Roles in a Food Chain
Within an ecosystem, every organism has a role. These roles are
divided into three groups:
1. Producers
2. Consumers
3. Decomposers
Producers:
Living things that make their own food from non-living things like
sunlight, water, and carbon dioxide.
They are also called autotrophs and are the source of all chemical
energy in an ecosystem.
Photosynthesis: Plants use sunlight + water + carbon dioxide →
glucose (sugar) + oxygen.
Examples: Plants, algae.
Consumers:
Consumers eat plants or other animals to gain energy.
They are called heterotrophs.
Types of Consumers:
- Herbivores: eat plants (cow, rabbit)
- Carnivores: eat animals (lion, eagle)
- Omnivores: eat both (human, bear)
Aquatic Food chain:
🌊 Marine (Saltwater) Food Chain
1. Phytoplankton → Tiny plants in ocean (base food).
2. Zooplankton → Tiny animals eat phytoplankton.
3. Small fish → Eat zooplankton.
4. Large fish → Eat small fish.
5. Seal → Eats large fish.
6. Shark → Top predator (eats seal).
🏞 Pond (Freshwater) Food Chain
1. Algae → Small green plants in pond.
2. Mosquito larvae → Eat algae.
3. Dragonfly larvae → Eat mosquito larvae.
4. Fish → Eat dragonfly larvae.
5. Duck → Eats fish.
Decomposers:
Break down dead plants, animals, and waste into nutrients
and recycle them back to the environment.
Examples: Bacteria, fungi, earthworms.
Complete Food Chain:
1. Grass (Producer): Makes food by photosynthesis.
2. Grasshopper (Primary Consumer): Herbivore, eats grass.
3. Bird (Secondary Consumer): Feeds on grasshopper.
4. Snake (Tertiary Consumer): Carnivore, eats bird.
5. Owl (Apex Predator): Top of the food chain, eats snake.
6.Mushroom (Decomposer): Breaks down dead matter, returns nutrients to soil
(helps grass grow again).
Energy flows in one direction (sun → producer → consumers → decomposers).
Nutrients are recycled back by decomposers.
Shows interdependence of organisms in an ecosystem.
Predator & Prey:
Predator: An animal that hunts and eats others (Lion eats Zebra).
Prey: An animal that is hunted for food (Zebra is prey).
Importance of Food Chains:
- Show how energy flows in nature.
- Keep balance in the ecosystem.
- Producers, consumers, and decomposers are all necessary for
life.
Types of food Chain
1. Grazing Food Chain (Starts from green plants)
This is the most common type of food chain.
It begins with producers (plants) that make food through
photosynthesis, then passes to herbivores (plant-eaters), and
then to carnivores (meat-eaters).
Example:
🌱 Grass → 🐇 Rabbit → 🦊 Fox → 🦅 Eagle
2. Detritus Food Chain (Starts from dead matter)
This chain begins with dead organic matter (detritus).
Then decomposers (fungi, bacteria) and detritivores (earthworms,
crabs, etc.) feed on it, passing energy to higher-level consumers.
3. Parasitic Food Chain (Based on parasites)
In this type, energy flows from larger organisms to
smaller parasites.
Parasites directly depend on living organisms for food, and
sometimes even hyperparasites (parasites on parasites)
are present.
Example: