Chapter 13 - Energy + Ecosystems - (13.1) Food chains and energy transfer Flashcards
This chapter covers: - how this energy is transferred - how nutrients are cycled - how we use artificial fertilisers to supplement natural nutrients in order to improve productivity
What is the ultimate source of energy for all organisms?
Sunlight is the ultimate source of energy. it is converted to chemical energy by plants. Most plants use sunlight in making organic compounds from carbon dioxide in the air or by water that surrounds them.
What are the 3 main groups in which organisms are divided into according to how they obtain their energy and nutrients?
Producers, Consumers and Saprobionts
What are producers?
A producer are photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide, and mineral ions.
What are consumers?
Consumers are organisms that obtain their energy by feeding on (consuming) other organisms rather than using the energy of the sunlight directly.
An example of a consumer is animals.
What is a primary consumer?
Those that directly eat producers (green plants). This is because they are first in the chain of consumers.
What is a secondary consumer?
Those animals that eat primary consumers.
What is a tertiary consumer?
Those eating secondary consumers.
What is a saprobionts?
Saprobionts (decomposers) are a group of organisms that break down the 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 can so contribute to recycling. The majority of work is carried out by fungi and bacteria.
What is a food chain?
A food chain describes a feeding relationship in which the producers are eaten by primary consumers, which are then eaten by secondary consumers, which are then eaten by tertiary consumers.
In a long food chain the tertiary consumers may be eaten by further consumers, also known as quaternary consumers.
What is a tropic level?
A tropic level refers to a level or position in a food chain, a food web or a ecological pyramid
What is a food web?
A food web consists of all food chains in a single ecosystem.
Most animals do not rely on one single food source and within a habitat many food chains will be linked together to form a food web. The problem with food webs is their complexity. It is unlikely that all organisms within a habitat, even within a ecosystem, will be linked to others in a food web.
What is biomass?
Biomass is the total mass of living material in a specific area at a given time.
The fresh mass is quite easy to assess, but the presence of varying amounts of water makes it unreliable.
Measuring the mass of carbon or dry mass overcomes this problem.
it is usually only made in a small sample, and this may not be representative.
How is biomass measured?
Biomass is measured using dry mass per given area, in a given time.
it is measured in grams per square metre where an area is being sampled.
Where volume is being measured, it is measured in grams per cubic metre.
The chemical energy store can be estimated using…
A calorimetry
In a bomb calorimetry, a sample of dry material is weighed and then is 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 how much heat (energy) is required to raise the temperature of 1g of water by 1 degree, if we know the volume of water and the temperature rise, we can calculate the energy released from the mass of burnt biomass.
