Which one of the following is the correct sequence of a food chain?

Defines plankton groups: microscopic plants like algae (phytoplankton) and animals like crustaceans (zooplankton), implying crustaceans are animal consumers in plankton communities.

A student can use the producer/consumer distinction to infer crustaceans are more likely to eat phytoplankton (diatoms) than vice versa.

States that communities include planktons, phytoplanktons and diatoms, and that algae and diatoms are important phytoplankton (i.e., primary producers).

Combine this with the idea that phytoplankton are at the base of marine food chains to test whether diatoms should precede crustaceans.

Explains that zooplanktons come up to graze phytoplanktons and that nekton fishes feed in these food webs, showing a typical flow: phytoplankton → zooplankton → fish.

A student could extend this pattern to check if herrings (nekton fish) feed on zooplankton/crustaceans rather than diatoms directly.

Gives the general rule that a food chain starts with producers and ends with top carnivores.

Use this rule plus evidence that diatoms are producers to judge whether they should be at the chain's base rather than between consumers and predators.

Notes that real ecosystems form food webs with multiple links; a single linear chain is a simplification but lower trophic levels commonly serve multiple consumers.

A student can use this to allow for alternate links but still expect producers (diatoms) to be consumed by crustacean zooplankton and those by fish like herrings.

Defines a food chain as a sequence that starts with producers and proceeds to higher trophic levels.

Use this rule to check whether diatoms (producers) occupy the first level and whether herrings or crustaceans occupy higher consumer levels in the proposed sequence.

States that plankton includes microscopic plants (phytoplankton, e.g., diatoms) and animals like crustaceans (zooplankton).

Combine with basic fact that diatoms are phytoplankton and crustaceans can be zooplankton to infer likely consumer–resource directions between them.

Notes that nekton fishes come up to graze phytoplanktons/zooplanktons and that many fishes feed on zooplankton.

Use the general statement that fish often eat zooplankton to evaluate whether herrings (nekton fish) would be predators of crustacean zooplankton or vice versa.

Explains that natural feeding relationships are often branching (food webs) rather than simple linear chains.

Remember that multiple possible predator–prey links may exist, so the simple sequence given should be checked against who typically eats whom in marine webs.

Places diatoms as important phytoplankton in coastal communities alongside fishes and crustaceans in the photic zone.

Combine this with geographic/basic ecological knowledge (coastal food webs) to judge plausible trophic links among diatoms, crustaceans and herrings.

Defines a food chain as starting with producers and ending with top carnivores, establishing an expected direction of energy flow.

A student can check which of the three items is a producer (should be at the base) to judge whether the given order is plausible.

States that plankton includes microscopic plants (phytoplankton) and animals like crustaceans (zooplankton), implying a producer → consumer relationship between phytoplankton and crustaceans.

Using the fact that diatoms are phytoplankton, a student can infer crustaceans are likely consumers of diatoms, so crustaceans → diatoms would reverse the expected direction.

Explains that zooplanktons come up to graze phytoplanktons and that nekton fishes (carnivorous nekton) come up at night to catch their prey, showing fishes feed on plankton/zooplankton.

A student can infer herrings (nekton fish) are likely to feed on zooplankton (crustaceans), supporting crustaceans → herrings rather than the other way around.

Notes that diatoms are important species of phytoplankton in marine communities alongside crustaceans in the photic zone, linking their coexistence in the same trophic environment.

Combining this with the producer/consumer roles lets a student place diatoms at the base, crustaceans as primary consumers, and fish (herrings) as higher consumers.