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carbohydrate digestionsimple sugars like glucose and fructose can be absorbed and metabolised directly but disaccharides such as sucrose or lactose
protein digestionenzymes that digest proteins are divided into two groups endopeptidases and exopeptidases according to site of their action in the
digestive enzymesnow let us consider the general principles of digestion that are applicable t6all animals we will start with the digestive enzymes
functional regions of digestive systemin general the digestive system of metazoans is divided into 4 major functional regions of reception
digestion the nutritional requirements and the various ways used by heterotrophic organisms to obtain nutrition whether food is used to give energy
feeding on liquids animals feeding on liquids are generally highly specialised for their feeding habits certain protozoa endoparasites and aquatic
minerals and trace elementsoxygen carbon hydrogen and nitrogen are the most common elements that make up 96 of the total weight of a mammal the next
waterwater is the most important constituent of all living tissue it forms up to 95 of the fresh weight of some animals we all know that water is
vitamins animals cannot sustain a healthy life if they are fed on a diet having only carbohydrates fats and proteins they also require vitamins in
lipids all animal tissues contain lipids or fats as essential components of cell membrane it is also stored in certain tissues lipids are bodys chief
carbohydrates fifty five to seventy per cent of the required energy in animals is derived from carbohydrates however fats and proteins can also be
proteinsproteins are continually synthesised in the cells as they are the principal component required for growth proteins are composed of amino
nutritionas we have said earlier all animals are heterotrophs and require food from the environment what is this food made up of if the food of a
nutrition feeding digestionall organisms require a fairly steady supply of nutrient materials from the environment to obtain energy in order to stay
metazoan branchesthe kingdom animalia comprises all the multicellular animals metazoans these are divided into three
classification of multicellular animalsthe multicellular animals animalia originated from the simpler protozoan protists you know the simpler
polyphyletic theory - metazoathis theory was suggested by greenheig 1959 and some other workers according to this theory sponges coelenterates
colonial theory - metazoa this is the most popular theory on the origin of metazoa the idea was conceived by haeckel 1874 modified by metschnikoff
origin and evolution of metazoamost of the early metazoans were soft bodied and so their fossils are rare the extremely fragmented fossil record does
regional specialisationregional specialisation takes place usually by three processes ndash1 restriction of certain structures to a few segments for
metameric segment - segmentationon the other hand true metameric segment as best observed in annelids has separate schizocoelic body cavity of
body cavity and coelom - metazoavacuoles spaces lacunae and cavities have been of importance in all organisms may it a be plant or animal all animals
germ layers - metazoathe infolding of the blastoderm of the blastula forms a gastrula with two or more layers the outer layer is the ectoderm and the
cleavage - metazoathe unicellular zygote begins cell division cleavage first the single cell divides forming two cells these redivide further to form
developmental patterns - metazoathe metazoans or animalia can be divided into two groups on the basis of body symmetry the bilateral metazoans can be