Modes of NutritionModes of Nutrition

Modes of NutritionModes of NutritionAUTROPHIC 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

Modes of NutritionModes of NutritionHETEROTROPHIC 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

Holozoic NutritionHolozoic NutritionInvolves 5 separate stages and a specialised gut:

- ingestion

- digestion

- absorption

- assimilation

- egestion

Two main types - HERBIVORES & CARNIVORES

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

HerbivoresHerbivores

HerbivoresHerbivores

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

HerbivoresHerbivores

Ruminant DigestionRuminant Digestion

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

HerbivoresHerbivores

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

CarnivoresCarnivores

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

CarnivoresCarnivores

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

Saprobiontic NutritionSaprobiontic Nutrition

see figure 6.6 page 119 NASsee figure 6.6 page 119 NAS

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)

Parasitic NutritionParasitic 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

Parasitic NutritionParasitic Nutrition

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

MutualismMutualism

• 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

MutualismMutualism

Modes of Nutrition Modes of Nutrition exam questionsexam questions

Modes of NutritionModes of NutritionStudy diagram A and answer the following questions:

1. Describe how the jaw action of herbivores such as sheep uses the interlocking surfaces of these teeth to chew plant material (2)

2. Suggest the function of the region labelled X (2)

3. Explain the importance of the rumen in digestion (2)

4. 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)

Modes of NutritionModes of Nutrition1. 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

Modes of NutritionModes of Nutrition2. 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

Modes of NutritionModes of Nutrition3. 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

Modes of NutritionModes of Nutrition4. 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

Modes of NutritionModes of Nutrition4. 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

Modes of NutritionModes of Nutrition4. 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)

Modes of NutritionModes of Nutrition4. 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.

Modes of NutritionModes of Nutrition5 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)

Modes of NutritionModes of Nutrition5. State where the adult stage of Taenia would be found in the body of the host

mammal (1)

- Small intestine / ileum / duodenum

Modes of NutritionModes of Nutrition6. 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

Modes of NutritionModes of Nutrition7. 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

Modes of NutritionModes of Nutrition8. 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

Modes of NutritionModes of Nutrition9 State the mode of nutrition carried out by Rhizopus (1)

10Explain how the hyphae are involved in the nutrition of Rhizopus (3)

11Rhizopus is an example of a heterotrophic organism. Explain how heterotrophic nutrition differs from autotrophic nutrition (2)

Modes of NutritionModes of Nutrition9. State the mode of nutrition carried out by Rhizopus (1)

- Saprotrophic / Saprobiontic / Saprophytic

Modes of NutritionModes of Nutrition10. 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

Modes of NutritionModes of Nutrition11. 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.

Modes of NutritionModes of NutritionUse the information sheet ‘Mutualism’ to answer the following questions

12The relationship between Rhizobium and a legume crop is an example of mutualism. Explain what is meant by the term mutualism (2)

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

14Explain why the addition of the Rhizobium inoculant to the soybean crops in the field trials increased the yield of beans (4)

15Compare the effect of the addition of the inoculant in South Dakota and Iowa (2)

16Suggest a reason for the difference you have described (1)

Modes of NutritionModes of Nutrition12. Explain what is meant by the term mutualism (2)

- Involves two species / types of organism

- Benefits both

Modes of NutritionModes of Nutrition13. State which species of bacterium would have been in the inoculant

used in the field trials (1)

- japonicum

Modes of NutritionModes of Nutrition14. 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

Modes of NutritionModes of Nutrition15. 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

Ecosystems & Ecosystems & Energy FlowEnergy Flow

Ecosystems & Energy Flow

Candidates should be able to recall the terms:

biosphere, ecosystem, habitat, producers, consumers, decomposers, trophic levels, food

chains and food webs

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

Ecosystems & Energy FlowAn ecosystem consists of two components…

BIOTIC ABIOTICAll living organisms that regularly come into contact with each other…

Producers

Consumers

Decomposers

Factors that affect the way in which organisms grow and carry out their activities

Light

Temperature

Water

Soil - etc

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.

Ecosystems & Energy Flow

HABITAT:

The locality in which an organism occurs (where the organisms is normally found)

Can be a microhabitat

Ecosystems & Energy Flow

Producers

Consumers

Decomposers

Ecosystems & Energy Flow

REVISION :

Food Chains

Food Webs

Pyramids of number

Pyramids of Biomass

Biomass – the mass of organisms per unit area of ground, kg per hectare. May be converted to an energy value, kj per hectare.

Ecosystems & Energy FlowTransfer of energyEnergy 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

Ecosystems & Energy FlowTransfer of energy through food chainsGrass - fix 1% sun’s energy falling on leaves

Grasshopper - incorporates ~10% of energy availableinto own biomass

Mouse - only ~10% of the energy available in the grasshopper converted into own biomass

So no more than 5 trophic levels…!

Ecosystems & Energy FlowPrimary 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.

Ecosystems & Energy FlowGross 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

Ecosystems & Energy FlowNet Primary Productivity (NPP)

The difference between GPP and losses due to respiration

Represents the biomass available for consumption by heterotrophs

Ecosystems & Energy FlowPyramid of energyShows 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