1.1 Many trees shed their leaves each year and most
animals produce droppings at least once a day. All
plants and animals eventually die. Microorganisms
play an important part in decomposing this material
so that it can be used again by plants. The same
material is recycled over and over again and can
lead to stable communities.
1.1.1 Living things remove materials from the environment for growth and other processes. These materials are
returned to the environment either in waste materials or when living things die and decay.
184.108.40.206 Materials decay because they are broken down
(digested) by microorganisms. Microorganisms
are more active and digest materials faster in
warm, moist, aerobic conditions.
220.127.116.11.1 The decay process releases substances that plants need to grow.
18.104.22.168.1.1 In a stable community, the processes that remove materials are balanced
by processes that return materials. The materials are constantly cycled.
2 B1.6.2 The Carbon Cycle
2.1 The constant cycling of carbon is called the carbon cycle.
2.1.1 Carbon dioxide is removed from the environment by photosynthesis. The carbon from the carbon dioxide is used to make
carbohydrates, fats and proteins for plants and algae. When they respire, some of this carbon forms carbon dioxide and is released
into the atmosphere. When plants and algae are consumed by animals, some of the carbon becomes part of the fats and proteins
that make up their bodies. When animals respire, some of this carbon forms carbon dioxide and is released into the atmosphere.
When plants, algae and animals die, some animals and microorganisms feed on their bodies. Carbon is released into the
atmosphere as carbon dioxide when these organisms respire. By the time the microorganisms and detritus feeders have broken
down the waste products and dead bodies of organisms in ecosystems and cycled the materials as plant nutrients, all the energy
originally absorbed by green plants and algae has been transferred. Combustion releases carbon dioxide into the atmosphere.