heterotrophic mode of nutrition in animals

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An autotroph, also called a producer, is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) from simple inorganic molecules using energy from light (by photosynthesis) or inorganic chemical reactions (chemosynthesis). They are the producers in a food chain, such as plants on land or algae in water. They are able to make their own food and can fix carbon. Therefore, they do not utilize organic compounds as an energy source or a carbon source. Autotrophs can reduce carbon dioxide (add hydrogen to it) to make organic compounds. The reduction of carbon dioxide, a low-energy compound, creates a store of chemical energy. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide. An autotroph converts physical energy from sun light (in case of green plants) into chemical energy in the form of reduced carbon.

Autotroph can be phototrophs or lithotrophs (chemoautotrophs). Phototrophs use light as an energy source, while lithotrophs oxidize inorganic compounds, such as hydrogen sulfide, elemental sulfur, ammonium and ferrous iron. Phototrophs and lithotrophs use a portion of the ATP produced during photosynthesis or the oxidation of inorganic compounds to reduce NADP+ to NADPH in order to form organic compounds.


Autotrophs are fundamental to the food chains of all ecosystems in the world. They take energy from the environment in the form of sunlight or inorganic chemicals and use it to create energy-rich molecules such as carbohydrates. This mechanism is called primary production. Other organisms, called heterotrophs, take in autotrophs as food to carry out functions necessary for their life. Thus, heterotrophs — all animals, almost all fungi, as well as most bacteria and protozoa— depend on autotrophs for the energy and raw materials they need. Heterotrophs obtain energy by breaking down organic molecules (carbohydrates, fats, and proteins) obtained in food. Carnivorous organisms ultimately rely on autotrophs because the nutrients obtained from their heterotroph prey come from autotrophs they consumed.


Some organisms rely on organic compounds as a source of carbon, but are able to use light or inorganic compounds as a source of energy. Such organisms are not defined as autotrophic, but rather as heterotrophic. An organism that obtains carbon from organic compounds but obtains energy from light is called a photoheterotroph, while an organism that obtains carbon from organic compounds but obtains energy from the oxidation of inorganic compounds is termed achemoheterotrophor chemolithoheterotroph.

Evidence suggests that some fungi may also obtain energy from radiation. Such radiotrophic fungi were found growing inside a reactor of the Chernobyl nuclear power plant.


  • Autotroph
    • Chemoheterotroph
    • Photoheterotroph

From Yahoo Answers

Question:it is about the development of early forms of life

Answers:It is very logical to assume so, because heterotrophic organisms are all "consumers" in the food chain. All animals are heterotrophic, as are some fungi and bacteria. Heterotrophs, unlike autotrophs, require nutrition from other heterotrophs (or autotrophs) to exist. Therefore, your deduction is entirely plausible and totally logical. PS, The Heterotrophic theory also has support from studies of the capabilities of RNA.

Question:There's a follow-up question after this: What is the comparison and contrast between the structures, nutrition and reproduction of the 5 kingdoms ( Monera, Protoctista, Fungi, Animalia, Plantae)? Please reply A.S.A.P. Thanks for helping.

Answers:The five-kingdom classification of organisms Nomenclature: Naming of organisms Binomial: Biological name of an organism Genus species Taxon: Set of organisms within a category / Taxonomy / Study of biological classification Different levels of taxons: SPECIES, GENUS, FAMILY, ORDER, CLASS, PHYLUM, KINGDOM Most number of species on right Most similar organisms on left Unicellular: Single cell; Colonial: Groups of cells; Multicellular: Many cells Autotrophs produce energy from inorganic sources Phototrophs from photosynthesis/sunlight Chemotrophs from simple inorganic (oxidative) processes Heterotrophs digest and absorb organic molecules Prokaryotae (prokaryotes) Cell structure: Prokaryotes, unicellular Prokaryotes lack cytoplasmic organelles found in eukaryotes Cell wall: murein Nutrition: autotrophic (photosynthesis, chemosynthesis), aerobic heterotrophs Divide by binary fission, not by mitosis 10 m in size (bacterial cell, filaments of blue-green bacteria) Mutualistic nitrogen-fixing bacteria live in nodules on the root of legumes / symbiotic Protoctista (protoctists) Cell structure: eukaryotes, unicellular and multicellular Cell wall: (sometimes) polysaccharide Nutrition: autotrophic, heterotrophic Placed in this category by exclusion / cannot be placed in any other kingdom Slime moulds / fungi characteristics Protozoa / heterotrophic and ingest food Algae / photosynthesis 10 m (amoeba) - 1m (Laminaria / large brown alga) Fungi Cell structure: eukaryotes, multicellular and unicellular (yeast) Cell wall: chitin Nutrition: heterotrophic / saprotrophic decomposers or parasitic Genus Penicillium Body of a fungus is composed of thin filaments called hyphae / form a mycelium Secret enzymes / external digestion / absorbs resulting nutrients Erect hyphae that grow upwards from the mycelium carry their reproductive spores Chains of spores on the erect hyphae / coloured mould visible on stored food Break down organic matter Plantae (plants) Cell structure: only multicellular, eukaryotic; large vacuoles Cell wall: cellulose Nutrition: autotrophic (photosynthetic) Growth is restricted to meristems (layers/patches of dividing cells) Non-motile; adapted to land / strong tissues, leave gas exchange system, waterproofed Eg mosses, ferns, conifers, angiosperms (flowering plants) Plant kingdom has two different types of adults in their life cycle Gametophytes, hidden in plant / sexual reproduction forms multicellular zygotes Sporophytes, what we call plant / asexual reproduction to form spores that germinate into gametophytes Gametophyte (n) gamete (n) fertilisation zygote (2n) mitosis sporophyte (2n) meiosis spore (n) mitosis gametophyte (n) Animalia (humans, animals) Cell structure: eukaryotic, multicellular, no cell wall Develop form a blastocyst / embryo Have nervous and hormonal control systems No cell wall! Nutrition: heterotrophic, involving a digestive system Are motile and grow throughout tissues (no mersitems)

Question:1. Among the characteristics unique to animals is a. gastrulation. b. multicellularity. c. sexual reproduction. d. flagellated sperm. e. heterotrophic nutrition. 2. Which of the following was the least likely factor causing the Cambrian explosion? a. the emergence of predator-prey relationships between animals. b. the accumulation of diverse adaptations, such as shells and different modes of locomotion. c. the movement of animals onto land d. the evolution of Hox genes that controlled development e. the accumulation of sufficient atmospheric oxygen to support the more active metabolism of mobile animals 3. Bilateral symmetry in the animal kingdom is best correlated with a. an ability to sense equally in all directions. b. the presence of a skeleton. c. motility and active predation and escape. d. development of a true coelom. e. adaptation to terrestrial environments. 4. Acoelomates are characterized by a. the absense of a brain. b. the absence of mesoderm. c. deuterostome development. a coelom that is not completely lined with mesoderm. e. a solid body without a cavity surrounding internal organs. 5. A direct consequence of indeterminate cleavage is a. formation of the archenteron. b. the ability of cells isolated from the early embryo to develop into viable individuals. c. the arrangement of cleavage planes perpendicular to the egg s vertical axis. d. the unpredictable formation of either a schizocoelous or enterocoelous body cavity. e. a mouth that forms in association with the blastopore.

Answers:1. a) Gastrulation. 2. c) The movement of animals onto land 3. c) Motility and active predation and escape. 4. e) A solid body without a cavity surrounding internal organs. 5. b) The ability of cells isolated from the early embryo to develop into viable individuals.

Question:autotrophs producers algae heterotrophs 2. Red blood cells contain a higher concentration of potassium than the surrounding blood plasma does. This higher concentration is maintained by the process of cyclosis osmosis simple diffusion active transport 3.Organisms are grouped into a five-kingdom classification system based on their structure and evolutionary relationships habitat food preferences social behavior

Answers:1.) Heterotrophs Heterotrophs consume only organic materials, compared to autotrophs, who synthesize and consume inorganic materials. 2. Active transport Active transport requires ATP and is the movement from a lower concentration to a greater concentration. This maintains a higher concentration. 3. Evolutionary relationships By using the process of elimination: Habitat is not a factor when grouping animals. Some animals live in different conditions than others, yet they are still each considered to be a member of the Kingdom Animalia. Food preferences has no significance at all, and same with social behavior. Therefore, the answer is evolutionary relationships, which is where the animal came from in terms of evolution and genetics.