Environmental Science/Introduction

Definitions

• Environment: Environment can be defined as one’s own surroundings including all of the living (biotic) and non-living (abiotic) factors that act on organism, population, or ecological community and influence its survival and development
• Abiotic factors: Physical conditions and non-living resources that affect living organism in terms of growth and reproduction. E.g. temperature, light intensity, carbon dioxide levels, pH of water and soil. Seasonal temperature variations affect when plants flower, when animals breed, when seeds germinate and when animals hibernate. Many types of plants grow better when they are fully exposed to sunlight. The pH of the soil can have an effect on the types of plants which can grow in it. They are divided into three categories:

1. Physical factors, e.g. sunlight, wind, water
2. Inorganic factors, e.g. minerals, oil, fuels, gasses
3. Organic factors, e.b. carbohydrates, proteins lipids, etc

• Biotic factors: a living component that affects the population of another organism, or the environment. They are divided into two parts.

1. Autotophs
2. Heterotrophs

• Organism: a living thing.
• Specie: similar organisms that can interbreed and produce fertile offsprings
• Population: total number of one type of organisms that live in one place
• Community: different populations living together in one habitat
• Ecosystem: a community of organisms and the environment they interact with
• Habitat: the place where an organism lives.
• Niche: the role a an organism plays in a community.
• Biosphere: the region where life exist
• Atmosphere: layer of gasses surrounding the earth
• Lithosphere: the earth crust consisting of the soil and rocks.
• Hydrosphere: is the water in all states (solid, liquid and gas). This comprises of all the surface and ground water such as seas, oceans, lakes, streams, glaciers, polar ice caps, and the water locked in minerals below earth crust.
• Producers, or autotrophs, make their own organic molecules.

1. Chemoautotrophs use energy from chemicals to build organic compounds out of carbon dioxide or similar molecules.
2. Photoautotrophs, such as plants, use energy from sunlight to make organic compounds

• Consumers, or heterotrophs, get organic molecules by eating other organisms.
• Food chain: a linear sequence of organisms through which nutrients and energy pass as one organism eats another.
• Food web: many interconnected food chains