GCSE BIOLOGY REVISION: ECOLOGY
Please note: Text in bold is what the AQA GCSE biology specification requires an understanding of.
Students should be able to extract and interpret information from charts, graphs and tables relating to the interaction of organisms within a community
The best way to get good at interpreting information is purely through practice. Find yourself questions from school, your textbook, revision guides or past paper questions. You can even use different exam board questions as all exam boards hold the same principles helping you to gain valuable skills. Background knowledge from mathematic and other scientific studies will also be useful for obtaining full marks on these types of questions as well as supporting biological knowledge. Exam questions based on data are an easy way to gain marks as it is not factual recall, however, it is also easy to lose marks through not reading the question correctly.
Students should be able to explain how a change in an abiotic factor would affect a given community given appropriate data or context.
Abiotic (non-living) factors which can affect a community are:
• light intensity
• moisture levels
• soil pH and mineral content
• wind intensity and direction
• carbon dioxide levels for plants
• oxygen levels for aquatic animals.
Abiotic factors are non-living factors that affect environments, for example: light intensity, temperature, carbon dioxide levels, oxygen levels, soil pH and mineral content, and moisture levels. This is not to be confused with biotic factors. In the exam, they could ask you questions on being able to distinguish between biotic and abiotic factors. Candidates often confuse abiotic with non-natural factors, this is not the case. Abiotic factors can be natural, by non-living we mean that is not a living organism that is influencing the environment.
So how do these factors affect the environment?
Increased light intensity is a factor that can increase plant growth, you may have plants at home, many of which may be on your windowsill to enable optimal sunlight. Remember, light doesn’t just affect plants, there are organisms that are adapted to living in environments where there is little or no sunlight throughout the day and night. Organisms that are not adapted to living in such conditions will not be found in these areas.
Temperature affects plant growth and animal communities. Think, in hot arid climates what kind of organisms do we find? Cacti, camels, thorny devil, deerstalker scorpion… They are all adapted to living in this extreme environment. Adversely in extreme cold environments we find penguins and polar bears.
Soils rich in minerals and nutrients are perfect for optimal plant growth. Areas that are lacking become a limiting factor for plant growth, creating more competition within and between plant species. In conditions that are too alkaline some plants will not survive as they prefer acidic conditions, like azaleas. Some plants prefer alkaline soils, like clematis and so will quickly die in acidic soils.
Moisture levels affect plant growth. Most plants are unable to survive in waterlogged soils due to roots not being able to respire, thus killing them. Other plants thrive in such conditions.