2.2.6 [HL] Nutritional Roles of Organisms

Learning Objectives

Distinguish autotrophs from heterotrophs
Distinguish photoautotrophs from chemoautotrophs
Outline ecological productivity

Part 1: autotrophs VS heterotrophs

Autotrophs

Heterotrophs

Autotrophs

•synthesize carbon compounds from inorganic sources of carbon

and other elements.

•All autotrophs are producers, including plants, algae and

photosynthetic bacteria.

•Types: Photoautotrophs and chemoautotrophs

•Photoautotrophs acquire energy by processing sunlight with nutrients through photosynthesis.

•Chemoautotrophs synthesize energy by converting inorganic substances through a chemical reaction called chemosynthesis. Chemoautotrophs get energy from inorganic molecules, such as sulfur or iron, by oxidizing them

Heterotrophs

•are consumers that obtain carbon compounds from other organisms.

•All living organisms can be classified as autotrophs or heterotrophs.

Photoautotrophs

Organisms that use sunlight energy to create their own food are called photoautotrophs. All green plants are photoautotrophs but not all producers use sunlight to make food. For example, some bacteria use chemical energy rather than sunlight to make sugars

Chemoautotrophs

Chemosynthetic bacteria are part of the nitrogen cycle. Most prokaryotes are chemoheterotrophs. They depend on other organisms for both energy and carbon. Many break down organic wastes and the remains of dead organisms

<< Giant tube worms (Riftia pachyptila) live on or near deep-sea hydrothermal vents. They have a symbiotic relationship with chemosynthetic bacteria using hydrogen sulfide and CO2 to produce sugars

Part 2: Ecological Productivity

Productivity in ecosystems

Production of biomass per unit area per unit time
Productivity occurs at each level of a food chain
Depending on where productivity occurs, it is referred to as primary productivity or secondary productivity
- - Primary productivity
    - - the gain by producers (autotrophs) in energy or biomass per unit area per unit time.
  - Secondary productivity
    - - the biomass gained by heterotrophic organisms, through feeding and absorption, measured in units of mass or energy per unit area per unit time.

Exercise:

Complete the following table

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