Life Processes (Organismal Level)
MULTICELLULAR ORGANISMS
The complex multicellular animals and plants perform many different activities in order to exist. More energy is invested in all organisms for their accumulation and distribution of food, release of waste matters, movement, reproduction, and coordination of these activities. The different organisms have specialized tissues, organs and organ systems that work together for the good of the organisms. Thus the well-being of the whole organism depends on the integration of all its parts.
THE DIGESTIVE SYSTEM
Digestion is a process of breaking down large complex food substances into simple molecules that can be used by each cell. Most of the foods of organisms consist of carbohydrates, fats, and proteins. Each of these large molecules acted upon by special kinds of digestive systems that speed up digestion by hydrolysis or splitting of molecules. Food also includes smaller molecules such as water, minerals and vitamins.
DIGESTION IN PLANTS
Plants do not have specialized digestive organs. However plants, like the Venus fly trap and the Pitcher have the ability to capture insects and digest them in special cavities in the leaves. These are called insectivorous plants. This process is called extracellular digestion because it takes place outside the cells. Nongreen plants called fungi as in bread molds digest dead plant and animal material. Bread molds secrete enzymes that diffuse out of the cells to digest food and then absorb the products into the cells. Figure 6.3 illustrates examples of extracellular digestion.
DIGESTION IN LOWER FORMS OF ANIMALS
In some organisms like the Amoeba and the Paramecium the large molecules and the solid particles are taken in by cells and digested by enzymes. This is intracellular digestion. The parts of the cell are made up of the same kind of molecules as the food that the enzymes of the cell digest. Why don’t the enzymes inside the cells digest the cells themselves? Food
The complex multicellular animals and plants perform many different activities in order to exist. More energy is invested in all organisms for their accumulation and distribution of food, release of waste matters, movement, reproduction, and coordination of these activities. The different organisms have specialized tissues, organs and organ systems that work together for the good of the organisms. Thus the well-being of the whole organism depends on the integration of all its parts.
THE DIGESTIVE SYSTEM
Digestion is a process of breaking down large complex food substances into simple molecules that can be used by each cell. Most of the foods of organisms consist of carbohydrates, fats, and proteins. Each of these large molecules acted upon by special kinds of digestive systems that speed up digestion by hydrolysis or splitting of molecules. Food also includes smaller molecules such as water, minerals and vitamins.
DIGESTION IN PLANTS
Plants do not have specialized digestive organs. However plants, like the Venus fly trap and the Pitcher have the ability to capture insects and digest them in special cavities in the leaves. These are called insectivorous plants. This process is called extracellular digestion because it takes place outside the cells. Nongreen plants called fungi as in bread molds digest dead plant and animal material. Bread molds secrete enzymes that diffuse out of the cells to digest food and then absorb the products into the cells. Figure 6.3 illustrates examples of extracellular digestion.
DIGESTION IN LOWER FORMS OF ANIMALS
In some organisms like the Amoeba and the Paramecium the large molecules and the solid particles are taken in by cells and digested by enzymes. This is intracellular digestion. The parts of the cell are made up of the same kind of molecules as the food that the enzymes of the cell digest. Why don’t the enzymes inside the cells digest the cells themselves? Food