Abiotic and biotic factors

Availability of food—> all animals eat other living organisms e.g lions eat other animals whereas animals such as zebras eat plants. All sources of food are a biotic factor.

If the availability of food falls, then the number of organisms in that community will also fall.

Another biotic factor is the arrival of a new predator—→ this can cause the population of a prey species to fall. New predator can also affect existing predators if they are competing for the same prey.

Another biotic factor is —→ Competition between species is another biotic factor if a species is outcompeted then its population can fall so much that numbers are no longer sufficient to breed and the species can become extinct.

Final biotic factor —> new pathogens, if an infectious disease emerges and then spreads it can wipe out a population of a species.

First abiotic factor—→ light intensity and this can have major affect on plants all plants need to light to carry out photosynthesis. However if the light intensity is too low then the rate of photosynthesis falls and plants will grow more slowly. The impact in the community is that if plants grow more slowly then animals which feed on plants will not babe enough food.

Temperature abiotic factor—→ if the temp of an environment changes this could cause the distribution of species to change. E.g animals could migrate and plant species might simply disappear from that area.

Water abiotic factor—→ both plants and animals needs water to survive. Many species are adapted to low levels of water.

pH and mineral content of the soil is an important abiotic factor for plants—» many plants cannot grow or soil that is too acidic or too alkaline. Plants also need certain mineral in the soil. For example nitrate which is used to make amino acids for proteins.

Wind intensity and direction abiotic factor—> strong winds blowing inland from the sea can cause plants to lose water. So plants growing in sand dunes are often adapted to reduce water loss.

Carbon dioxide and oxygen abiotic factor—» carbon dioxide is needed for plants to photosynthesise and if carbon dioxide levels fall the rate of photosynthesis can also decrease. Oxygen is needed for aerobic respiration. The level of dissolved oxygen in water can fall for e,g on hot days. This can be harmful to aquatic organisms such as fish.