Transcript modes of nutrition & Ecosystems

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
- Chemosynthetic organisms use energy from chemical reactions eg
some prokaryotes
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
Holozoic Nutrition
Involves 5 separate stages and a specialised gut:
- ingestion
- digestion
- absorption
- assimilation
- egestion
Two main types -
HERBIVORES & CARNIVORES
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
Herbivores
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
Ruminant Digestion
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
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
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
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
see figure 6.6 page 119 NAS
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)
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
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
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
Modes of Nutrition
exam questions
Modes of Nutrition
Study 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 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
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
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
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
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
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)
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.
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)
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
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
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
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
Modes of Nutrition
9 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 Nutrition
9. State the mode of nutrition carried out by Rhizopus (1)
- Saprotrophic / Saprobiontic / Saprophytic
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
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.
Modes of Nutrition
Use 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 Nutrition
12.
Explain what is meant by the term mutualism (2)
- Involves two species / types of organism
- Benefits both
Modes of Nutrition
13.
State which species of bacterium would have been in the inoculant
used in the field trials (1)
- japonicum
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
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
Ecosystems &
Energy 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 Flow
An ecosystem consists of two components…
BIOTIC
All living organisms that
regularly come into
contact with each other…
ABIOTIC
Factors that affect the way in
which organisms grow and
carry out their activities
Producers
Light
Consumers
Temperature
Decomposers
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 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
Ecosystems & Energy Flow
Transfer of energy through food chains
Grass
- fix 1% sun’s 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…!
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.
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
Ecosystems & Energy Flow
Net Primary Productivity (NPP)
The difference between GPP and losses due to respiration
Represents the biomass available for consumption by
heterotrophs
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