bio eco 2

Cellular respiration

The process of breaking down glucose with oxygen to make ATP (usable energy), releasing carbon dioxide and water; occurs in mitochondria of plants and animals with enzyme help.

Photosynthesis

Process where plants, algae, and some bacteria use sunlight, carbon dioxide, and water to make glucose and oxygen (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂).

Food chain

A simple path of energy flow showing who eats whom in an ecosystem; always starts with a producer and ends with a top consumer.

Top consumer

The highest predator in a food chain with no natural enemies (e.g., hawk, shark, wolf).

Food web

Many connected food chains that show the full feeding network of an ecosystem; consumers can occupy more than one trophic level.

Role of producers

Capture light energy and make chemical energy (glucose) that supports all other organisms.

Autotrophs vs heterotrophs

Autotrophs make their own food from inorganic sources (photoautotrophs use sunlight, chemoautotrophs use chemicals). Heterotrophs must eat other organisms for energy.

Primary vs secondary consumer

Primary consumers eat producers (herbivores). Secondary consumers eat primary consumers (carnivores or omnivores).

Trophic level

A feeding step in a food chain or web, such as producer, primary consumer, secondary consumer, or top consumer.

Typical top consumers

Large predators like hawks, wolves, or sharks.

Energy transfer

Only about 10% of energy moves from one trophic level to the next; the rest is lost.

Energy loss forms

Heat from metabolism and movement, excretion, faeces, and unconsumed material.

Why food chains are short

Less energy is available at higher levels, so only a few trophic levels can be supported.

Energy flow vs nutrient cycling

Energy enters as sunlight and leaves as heat (one-way). Nutrients are recycled by decomposers and reused by producers.

Ecological pyramids

Three ways to show energy and matter: pyramid of numbers, pyramid of biomass, and pyramid of energy.