Trophic levels and extracellular decomposition
הוצג| English | משמעות |
|---|---|
| trophic level/ˈtrəʊfɪk ˈlevl/ | רמת טרופית |
| extracellular digestion/ˌekstrəˈseljʊlə daɪˈdʒestʃn/ | עיכול מחוץ לתא |
What would explain this observation?
- A decomposer acts on dead material from several trophic levels 营养级. It is not simply the next predator above an apex consumer.
Build the model
- Trophic level 1 contains producers such as plants and algae.
- Primary consumers at level 2 eat producers; secondary consumers at level 3 eat primary consumers; tertiary consumers at level 4 eat secondary consumers.
- An apex predator has no predators in the stated ecosystem.
- Level refers to a feeding position rather than size or intelligence.
- trophic level: An organism’s feeding position along a stated food chain.
- extracellular digestion 细胞外消化: Enzyme digestion outside cells before products are absorbed.
Where do decomposer enzymes first act in this account?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Decomposers secrete enzymes onto the dead material, digesting it OUTSIDE the cell and absorbing the soluble products - extracellular digestion. It happens neither in a hawk's nucleus nor in sunlight.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Decomposers break down dead plants, animals and waste.
- They secrete enzymes into their surroundings; enzymes digest large molecules into small soluble products that diffuse into the microorganism.
- This extracellular digestion lets material from several levels return to the system through microbial activity and material cycling.
In the lab: Label a supplied food chain and use the arrow legend to identify feeding positions. In a food web an organism may occupy different positions along different routes. Trace dead material separately to decomposers. Use prepared diagrams rather than feeding experiments or unknown microbial cultures.
Which two habits make the investigation or model in this case more defensible?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- Known: a model chain contains grass → insect → bird → hawk.
- Grass is level 1, insect level 2, bird level 3 and hawk level 4.
- There are three feeding transfers from grass to hawk.
- The number of transfers is one less than the number of levels in this linear chain.
Your turn: A linear chain has five feeding levels. Find the number of transfers from first to last.
A linear chain has five feeding levels. Find the number of transfers from first to last.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 4 transfers. Known: five feeding levels in a linear chain. Each transfer moves between adjacent levels, so transfers = levels - 1 = 5 - 1 = 4. The first level needs no transfer to exist.
Check the conclusion and its limits
- Carnivore does not always mean level 3: a carnivore eating another carnivore can be level 4.
- Enzymes act outside a decomposer before soluble products enter it.
- The apex label depends on the supplied ecosystem, not a universal claim about the species.
Not true: Every carnivore must occupy trophic level 3. A carnivore's level depends on what it eats: eating herbivores puts it at level 3, but eating other carnivores puts it at level 4 or higher. Level 3 is not assigned to every carnivore.
- Trophic level 1 contains producers such as plants and algae.
- Decomposers break down dead plants, animals and waste.
- Watch for: carnivore does not always mean level 3: a carnivore eating another carnivore can be level 4.
Every carnivore must occupy trophic level 3.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
A carnivore's level depends on what it eats: eating herbivores puts it at level 3, but eating other carnivores puts it at level 4 or higher. Level 3 is not assigned to every carnivore.
An organism’s feeding position along a stated food chain: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
trophic level means An organism’s feeding position along a stated food chain.