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Modes of Nutrition

Modes of Nutrition. Modes of Nutrition. AUTROPHIC ORGANISMS Use external sources of energy to synthesise their own organic food materials, which are often expired to release energy: Photosynthetic organisms use light energy eg plants or algae

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Modes of Nutrition

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  1. Modes of Nutrition

  2. Modes of Nutrition • AUTROPHIC ORGANISMS • Use external sources of energy to synthesise their own organic food materials, which are often expired to release energy: • Photosynthetic organisms use light energy eg plants or algae • Chemosynthetic organisms use energy from chemical reactions eg some prokaryotes

  3. Modes of Nutrition • HETEROTROPHIC ORGANISMS • Use ready made organic food materials by feeding on plants/algae or animals that have eaten plants or algae. Energy is released from the food by respiration • Four types of heterotrophic nutrition: • Holozoic • Saprobiontic • Parasitic • Mutualism

  4. Holozoic Nutrition Involves 5 separate stages and a specialised gut: - ingestion - digestion - absorption - assimilation - egestion Two main types - HERBIVORES & CARNIVORES

  5. Herbivores • eg – ruminants (cattle & sheep). Adaptations to a diet containing large quantities of cellulose • Specialised dentition: • No upper incisors – horny gum pad only • Small lower incisors and canines that cut / grip against horny pad • Diastema • Premolars and molars for grinding with ridges of enamel • Open roots • Loose jaw articulation

  6. Herbivores

  7. Herbivores • eg – ruminants (cattle & sheep). Adaptations to a diet containing large quantities of cellulose • Complex gut containing 3 additional compartments: • rumen • reticulum • omasum • true (gastric) stomach (abomasums) is also retained

  8. Ruminant Digestion

  9. Herbivores • eg – ruminants (cattle & sheep). Adaptations to a diet containing large quantities of cellulose • Complex digestion: • Food enters rumen for up to 30hrs • Coarse material regurgitated & re-swallowed • Microbes digest cellulose to hexoses • Fermentation • Proteins also broken down by microbes

  10. Carnivores • eg – dogs show adaptations to a diet consisting of other animals • Specialised dentition: • Sharp incisors • Large canines • Carnassial teeth • Sharp & pointed premolars and molars • Tight jaw articulation • Simple gut

  11. Carnivores • eg – dogs show adaptations to a diet consisting of other animals • Adaptations for hunting: • Forward facing eyes • Night vision • Speed • Camouflage • Claws • Some hunt socially

  12. Saprobiontic Nutrition • eg – many bacteria & fungi • Primary consumers in detritus food chains • Extracellular digestion • Eg Rhizopus (bread mould) • Mycelium made up of aerial hyphae called stolons • Secrete enzymes • Products absorbed & used for metabolism or stored

  13. see figure 6.6 page 119 NAS

  14. Parasitic Nutrition • live in close association with another organism (host). Dependent on host for food • Ectoparasitic or endoparasitic • Usually cause some harm to host • Eg Taenia (pork tapeworm)

  15. Parasitic Nutrition • Taenia solium – the pork tapeworm • Adult stage in human small intestine • Protected from host enzymes • Anterior end is scolex • Zone of proliferation – proglottids form – long & thin • Self fertilisation • Larvae develop in muscles of pig

  16. Mutualism • When two organisms live in a close relationship in which both contribute and both benefit • Eg nitrogen fixing bacteria Rhizobium and members of the Papilionacceae (pea plant family) • Rhizobium benefits from a source of carbohydrates from plant • Plant benefits from a source of ammonia / amino acids from the Rhizobium

  17. Mutualism • Rhizobium attracted to plant roots • Rhizobium penetrate root hair cells • Rhizobium moves into root cortex – stimulates auxin production • Nodules form containing large numbers of Rhizobium • Bacteroids form, able to fix nitrogen in anaerobic conditions • Leghaemologlobin pigment absorbs oxygen molecules • Rhizobium uses hydrogen (from carbohydrates of plant) to combine with nitrogen gas – forms ammonia

  18. Modes of Nutrition exam questions

  19. Modes of Nutrition • Study diagram A and answer the following questions: • Describe how the jaw action of herbivores such as sheep uses the interlocking surfaces of these teeth to chew plant material (2) • Suggest the function of the region labelled X (2) • Explain the importance of the rumen in digestion (2) • Describe three differences between the teeth of the sheep and the dog. For each difference, explain how it is related to the differences in their diets (6)

  20. Modes of Nutrition 1. Describe how the jaw action of herbivores such as sheep uses the interlocking surfaces of these teeth to chew plant material (2) - Side to side / rotating / circular movements of jaw - Ridges of enamel on teeth act as cutting edges - Interlocking surfaces for grinding

  21. Modes of Nutrition 2. Suggest the function of the region labelled X (2) - Manipulation of grass / food - To expose different surfaces to teeth - To keep chewed grass separate from fresh grass

  22. Modes of Nutrition 3. Explain the importance of the rumen in digestion (2) - Fermentation / breakdown / digestion of cellulose / fibrous material / cell walls - By microorganisms / gut fauna / bacteria / protozoa - Regurgitation / rechewing - Storage or time for action of bacteria / explanation of second digestion

  23. Modes of Nutrition 4. Describe three visible differences between the teeth of the sheep and the dog. For each difference, explain how it is related to the differences in their diets (6) 1 (a) Incisors in sheep on lower jaw only OR reference to horny pad on upper jaw. Incisors in dog present on upper and lower jaw (b) Chopping / cutting / cropping / tearing in sheep – gripping / nibbling in dog

  24. Modes of Nutrition 4. Describe three visible differences between the teeth of the sheep and the dog. For each difference, explain how it is related to the differences in their diets (6) 2 (a) Canines are small / absent / only in lower jaw in sheep. Canines are large / pointed in the dog (b) Dogs require large pointed canines for gripping / stabbing

  25. Modes of Nutrition 4. Describe three visible differences between the teeth of the sheep and the dog. For each difference, explain how it is related to the differences in their diets (6) 3 (a) Sheep have diastema (gaps between canines / incisors and premolars). Dog has no gap. (b) Used in sheep for manipulation of food bolus (by tongue)

  26. Modes of Nutrition 4. Describe three visible differences between the teeth of the sheep and the dog. For each difference, explain how it is related to the differences in their diets (6) 4 (a) Premolars / molars of sheep are ridged, interlocking / not sharp. Premolars / molars of dog are pointed / sharp / not interlocking. (b) Sheep grind food. Dogs slice / shear / cut / crush bone.

  27. Modes of Nutrition 5 State where the adult stage of Taenia would be found in the body of the host mammal (1) 6 Explain how the hooks and suckers enable Taenia to be a successful endoparasite (2) 7 Give two features of Taenia, other than those in the picture that are adaptations to the parasitic mode of nutrition (2) 8 Explain how the mode of nutrition shown by a parasite, such as Taenia, differs from that shown by a fungus, such as Rhizopus(3)

  28. Modes of Nutrition 5. State where the adult stage of Taenia would be found in the body of the host mammal (1) - Small intestine / ileum / duodenum

  29. Modes of Nutrition • 6. Explain how thye hooks and suckers enable Taenia to be a successful endoparasite (2) • Enables grip to the walls of the alimentary canal • Prevents it being carried away by peristalsis

  30. Modes of Nutrition • 7. Give two features of Taenia, other than those shown in the picture, that are adaptations to the parasitic mode of nutrition (2) • No mouth / alimentary canal / digestive system • Lack of sense organs / reduced nervous system • Thick, enzyme resistant tegument/coat/covering/cuticle OR mucus secreted to protect against enzymes • Can tolerate low oxygen / anaerobic conditions • Prolific reproductive capacity - hermaphrodite • Flat body shape / large surface area to volume

  31. Modes of Nutrition • 8. Explain how the mode of nutrition shown by a parasite, such as Taenia, differs from that shown by a fungus, such as Rhizopus(3) • Rhizopus is a saprophyte / saprobiont / saprotrophic • Parasites feed from / live on host, Rhizopus feeds on / lives on dead material • No digestion of food / food already digested in Taenia and external digestion of food in Rhizopus • Absorption of food over whole body surface in Taenia and reference to mycelium / hyphae in Rhizopus

  32. Modes of Nutrition • State the mode of nutrition carried out by Rhizopus (1) • Explain how the hyphae are involved in the nutrition of Rhizopus(3) • Rhizopus is an example of a heterotrophic organism. Explain how heterotrophic nutrition differs from autotrophic nutrition (2)

  33. Modes of Nutrition • 9. State the mode of nutrition carried out by Rhizopus(1) • Saprotrophic / Saprobiontic / Saprophytic

  34. Modes of Nutrition • 10. Explain how hyphae are involved in the nutrition of Rhizopus (3) • Hyphae penetrate food/substrate – forms large surface area in contact with food – anchors organism onto substrate • Secretes enzymes onto substrate • Named enzyme and substrate – hydrolysis / breakdown of large compounds to small • Uptake/absorption of soluble products of digestion • Reference to external / extracellular digestion

  35. Modes of Nutrition • 11. Rhizopus is an example of a heterotrophic organism. Explain how heterotrophic nutrition differs from autotrophic nutrition(2) • Heterotrophs take in / can’t make organic compounds. Autotrophs use inorganic compounds and synthesise organic compounds • Heterotrophs rely on other organisms. Autotrophs use light / external energy / photosynthesis.

  36. Modes of Nutrition • Use the information sheet ‘Mutualism’ to answer the following questions • 12 The relationship between Rhizobium and a legume crop is an example of mutualism. Explain what is meant by the term mutualism(2) • State which of the species of bacterium would have been in the inoculant used in the field trials (1) • Explain why the addition of the Rhizobium inoculant to the soybean crops in the field trials increased the yield of beans (4) • Compare the effect of the addition of the inoculant in South Dakota and Iowa (2) • Suggest a reason for the difference you have described (1)

  37. Modes of Nutrition • 12. Explain what is meant by the term mutualism(2) • Involves two species / types of organism • Benefits both

  38. Modes of Nutrition • 13. State which species of bacterium would have been in the inoculant used in the field trials(1) • japonicum

  39. Modes of Nutrition • 14. Explain why the addition of the Rhizobium inoculant to the soybean crops in the field trials increased the yeild of beans (4) • Rhizobium is a nitrogen fixing bacterium • Converts nitrogen to ammonia / ammonium compounds • Reference to nitrogenase • This is used to form amino acids / proteins • Added to those in soil • Therefore more protein for growth

  40. Modes of Nutrition • 15. Compare the effect of addition of the inoculent in South Dakota and Iowa (2) • South Dakota has a greater increase in yield • X10 greater / 6.4% more • 16. Suggest a reason for this difference (1) • Climate / weather • Soil types / fertiliser • Difference in natural Rhizobium • Possibility of diseases

  41. Ecosystems & Energy Flow

  42. Ecosystems & Energy Flow Candidates should be able to recall the terms: biosphere, ecosystem, habitat, producers, consumers, decomposers, trophic levels, food chains and food webs

  43. Ecosystems & Energy Flow ECOSYSTEM: A stable, settled unit of nature consisting of a community of organisms interacting with each other and with their surrounding physical and chemical environment. Eg: Pond – Forest – Sea shore - Savannah

  44. Ecosystems & Energy Flow An ecosystem consists of two components… BIOTIC ABIOTIC Factors that affect the way in which organisms grow and carry out their activities Light Temperature Water Soil - etc All living organisms that regularly come into contact with each other… Producers Consumers Decomposers

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