The two membranes pull apart a little and create a small pocket or sack of air. As the developing bird grows, it breathes in oxygen from the air sack and exhales carbon dioxide. Several thousand microscopic pores all over the surface of the egg allow the CO2 to escape and fresh air to get in.
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Biotic factors include plants, animals, microbes, etc. The important abiotic factors include the amount of sunlight in the ecosystem, the amount of oxygen and nutrients that is dissolved in the water, temperature, etc. Sunlight is one of the most important abiotic factors for marine ecosystems.
Root hair cells are adapted for taking up water and mineral ions by having a large surface area to increase the rate of absorption. They also contain lots of mitochondria , which release energy from glucose during respiration in order to provide the energy needed for active transport.
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You put sand in the furnace
Planarias are flat worms that live freely in freshwater and sometimes in teh logs, soil, plants, or other dump or humid areas. They are from the class of Turbellarians. They have a very good ability in regeneration. They are acoelomerate which means that their body is very solid without any hollows.
They excrete unwanted objects from their body using their excretory system which is consists of series of tubes with length similar to their body length. The flame cells remove excess water through the use of the cilia and pass them to the ducts. At the end of the duct, there exist pores called the nephridiapores.