Biomass and Trophic Levels

Biomass and Trophic Levels

We all get our energy from the sun in one way or another from the sun. Plants and algae absorb light which transfer this energy into chemical energy during photosynthesis.

Only 1% of light hitting Earth is used for photosynthesis (incident energy)

Energy is passed along a food chain from one organism to another as they eat each other. Each stage of the food chain is called a trophic level. Producers of energy like plants and algae are in trophic level 1 where the consumers like us humans are in trophic level 4.

Trophic Level 1: Producers that make their won food from photosynthesis, dependent on sunlight. Plants and algae

Trophic Level 2: Primary consumers. These are the herbivores that eat the plants and algae.

Trophic Level 3: Secondary consumers. These are the carnivores that eat the herbivores.

Trophic Level 4: Tertiary consumers. These are the carnivores that eat other carnivores. Apex predators are carnivores with no predators- found at the top of the food chain.

Lion (Michael Spain)

Biomass is the mass of material in living organisms. As animals and plants die, they recycle and are broken down by decomposers. The decomposers releases enzymes to digest the dead matter and then absorb the nutrients by diffusion.

To show the biomass in each stage of the food we can use pyramids of biomass. This biomass can be classified as dry mass or wet mass (these can vary due to weather, climate etc.). This pyramid takes into consideration qualities like number and the size of the matter.

As we go along the trophic levels of the food chain, there is less biomass because the energy is transferred as the beings respire in each stage. There are almost always more producers than consumers in a food chain because energy is lost through each stage. Some of the energy is kept which means it become the biomass, but some energy is lost in many ways.

In herbivores, they do not have the enzymes to digest cellulose in plant cell wall so much of the plant is egested (passed out of the body)

Energy loss can occur in many ways:

·         Parts of the plant/ animal are hard to digest so are egested

·         Carnivores lose energy when excess protein is excreted in urea

·         Significant amounts of energy from the biomass is released in respiration

·         Movement of mammals requires significant energy

·         Homeostasis- maintaining body temperature, transferred to surroundings

 (Steve Harvey)

When an animal eats another organism, the biomass is passed on through the food chain and is used for growth. However, some energy will be lost. Part of the plant or animal are hard to digest and break down, so energy is lost in the formation of faeces. Carnivores will lose energy when excess protein is passed out as urea in urine. The biomass eaten will be used in respiration and some of this energy will be lost to the surroundings. 

Movement requires a lot of energy from respiration so the more active the mammal is, the more energy lost. Mammals and birds also lose thermal energy through homeostasis to their surroundings. This is to maintain their optimum body temperature.