Modes of Nutrition

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Modes of Nutrition
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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

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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

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

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Herbivores
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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

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Ruminant Digestion
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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

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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

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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

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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

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see figure 6.6 page 119 NAS
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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)

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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

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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

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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

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Modes of Nutrition exam questions
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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)

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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
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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
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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
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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
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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
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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)
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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.
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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)
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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
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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

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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/cut
  icle 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

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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

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Modes of Nutrition

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

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Modes of Nutrition

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

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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

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Modes of Nutrition

• 11. Rhizopus is an example of a heterotrophic
  organism. Explain how heterotrophic nutrition
  differs from autotrophic nutrition (2)
• Heterotrophs take in / cant make organic
  compounds. Autotrophs use inorganic compounds
  and synthesise organic compounds
• Heterotrophs rely on other organisms. Autotrophs
  use light / external energy / photosynthesis.

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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)

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Modes of Nutrition

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

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Modes of Nutrition

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

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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

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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

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Ecosystems Energy Flow
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Ecosystems Energy Flow
Candidates should be able to recall the
terms biosphere, ecosystem, habitat, producers,
consumers, decomposers, trophic levels, food
chains and food webs
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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
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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 Temperat
ure Water Soil - etc
All living organisms that regularly come into
contact with each other Producers Consumers Decom
posers
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Ecosystems Energy Flow
BIOSPHERE The restricted zone in which living
things inhabit. For the majority of organisms
this is from the upper soil to the lower
atmosphere.
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Ecosystems Energy Flow
HABITAT The locality in which an organism occurs
(where the organisms is normally found) Can be a
microhabitat
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Ecosystems Energy Flow
Producers Consumers Decomposers
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Ecosystems Energy Flow
REVISION Food Chains Food Webs Pyramids of
number Pyramids of Biomass
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Biomass the mass of organisms per unit area of
ground, kg per hectare. May be converted to an
energy value, kj per hectare.
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Ecosystems Energy Flow
Transfer of energy Energy from the sun, trapped
by photosynthesis, provides the source of energy
for all living organisms 0 5 joules solar
energy per sq metre / min Only small absorbed
by chlorophyll and converted into chemical
energy Reflected passes through wavelengths
not used in photosynthesis Wastage due to
biochemical inefficiency of the reactions of
photosynthesis
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Ecosystems Energy Flow
Transfer of energy through food chains Grass -
fix 1 suns energy falling on leaves Grasshopper
- incorporates 10 of energy available into
own biomass Mouse - only 10 of the energy
available in the grasshopper converted into own
biomass So no more than 5 trophic levels!
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Ecosystems Energy Flow
Primary Productivity The rate at which biomass
is produced per unit area by green
plants Expressed as mass or energy Rate of
accumulation of biomass kilojoules per unit area
per year (kj ha -1 yr -1) or kg.
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Ecosystems Energy Flow
Gross Primary Productivity (GPP) The total amount
of energy captured by green plants in
photosynthesis kj / m2 / year Plant uses some
organic materials produced GPP ultimately lost
as heat The rate at which these are used plant
respiration (R) kj / m2 / year
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Ecosystems Energy Flow
Net Primary Productivity (NPP) The difference
between GPP and losses due to respiration Represen
ts the biomass available for consumption by
heterotrophs
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Ecosystems Energy Flow
Pyramid of energy Shows productivity for each
level in ecosystem Productivity is a measure of
the energy content of each level Can be obtained
by converting the mass of new organic material
produced per unit area per year into an
equivalent energy value kj m -2 yr -1
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