Biomass and energy transfer

What is biomass?

Mass of a living material present in a place or a particular organism, it can be equated to energy content

How do you calculate the biomass at each trophic level?

Multiply biomass of each organism by the total number of organisms

Why is only 1% of the energy that reaches the consumer converted to plant biomass?

Building/breakdown of proteins, respiration, some light hits non-photosynthetic parts like bark, some light passes straight through the leaf and misses chloroplasts, some light is reflected off of the plant as only certain wavelengths of light can be absorbed

Why is energy lost from each trophic level?

Excretion, digestion, not all parts of food aren’t eaten, movement and bodily processes, heat energy lost in exothermic reactions such as respiration and movement, some parts of food aren’t eaten are indigestible

Why is energy transfer less efficient from producers to consumers?

As you move up a food chain, energy transfer tends to become more efficient. Plants contain a greater proportion of indigestible material than animals. Often less of the producer is available to be eaten

How do you measure efficiency of energy transfer?

Measure the biomass, use a calorimeter to measure the energy (burn a known mass of an organism and calculate how much heat energy is released from how much the temp of a known mass of water rises)

What is gross productivity?

Energy which is absorbed/taken in by an organism

What is respiratory heat loss?

Energy lost to the environment when an organism use energy released by respiration

What is net productivity?

Amount of energy available for the next trophic level

How can you improve primary productivity? (more energy converted to plant biomass)

Increase crop yields, irrigate crops, breed more drought resistant strains, control temp of greenhouses, nutrients in fertilisers, crop rotation, pesticide use/pest resistant strains, herbicide to kill weed competition

How can you improve secondary productivity?

Harvesting animals just before adulthood minimises energy loss, steroids, controlling conditions, antibiotics (unnecessary energy loss fighting pathogens), selective breeding of animals with high growth rate