13.1 Food chains and energy transfer Flashcards
How is sunlight the ultimate source of energy
. Sunlight is conserved as chemical energy by plants
. Plants use sunlight to make organic compounds from CO2 in air, or water that surrounds them
. These organic compounds are mostly used as substrates for respiration, and remainder make other groups of biological molecules
. Biological molecules form biomass of plants
What are producers
. Photosynthetic organisms that manufacture organic substances using light energy, water, mineral ions and CO2
What are consumers
. Organisms that obtain their energy by feeding on other organisms rather than using the energy of the sunlight directly
Eg animals are consumers
What are the 3 types of consumers
. Primary consumers directly eat producers eg green plants, and are first in chain of consumers
. Secondary consumers eat primary consumers
. Tertiary consumers eat secondary consumers
Secondary and tertiary are usually predators but they may also be parasites or scavengers
What are sabrobionts
Decomposers are a group of organisms that break down complex materials in dead organisms into simple ones
In doing so they release valuable minerals and elements in a form that can be absorbed by plants and so contribute to recycling
Majority of this work is carried out by fungi and bacteria
What is a food chain
It describes a feeding relationship where primary consumers eat producers
Then secondary consumers eat primary consumers
Then tertiary consumers eat secondary consumers
What is a trophic level
. In a food chain where one thing eats another, each stage is a trophic level
What are food webs
. Most animals don’t rely on a single food source and within a single habitat many food chains are linked together to form a food web
They are complex but more likely than food chains in an ecosystem
What is biomass
The total mass of living material in a specific area at a given time
What makes measuring biomass unreliable
. Although it is easy to access fresh mass, the presence of varying amounts of water make it unreliable
. So to do it you would have to dry the organism out and kill them
. Because of this it is only done on a small scale so isn’t representative
What is biomass measured in
Biomass is dry mass per given area
- Grams per metre squared
g/m^2
Where an area of land is being sampled eg grassland - It is grams per metre cubed for volume eg ocean or pond
What is a better way to measure biomass
Calorimetry
In bomb calorimetry, sample of dry material is weighed and burnt in pure oxygen within a sealed chamber called a bomb
The bomb is surrounded by a water bath and the heat of combustion causes a small temperature rise in this water
As we know the specific heat capacity of water, the temperature rise, and the volume of water
We can use q=mcat to measure amount of energy released from the mass burnt
In units eg kJkg^-1
