Practice Flashcards
Flip to reveal answersDefine a food web.
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 15 Flashcards — Food webs
Sign up free to track progress and get spaced-repetition review schedules.
Question
Define a food web.
Answer
A food web is a network of interconnected food chains showing multiple feeding relationships in an ecosystem.
💡 Hint
Interconnected food chains
Question
State what is meant by a food web.
Answer
A food web is a network of interconnected food chains.
💡 Hint
Interconnected chains
Question
Explain why food chains rarely exceed 4–5 trophic levels.
Answer
Energy transfer is inefficient; much energy is lost as heat and waste at each step, leaving too little to support many higher levels.
💡 Hint
Heat + waste
Question
Describe the trend in available energy at higher trophic levels.
Answer
Available energy decreases at each trophic transfer, so higher trophic levels have less energy and biomass.
💡 Hint
Decreases with level
Question
Explain why food webs represent ecosystems more realistically than food chains.
Answer
Most organisms feed on more than one species and have multiple predators, so energy can move through several pathways.
💡 Hint
Multiple pathways
Question
Outline how multiple feeding links can increase resilience.
Answer
Alternative feeding pathways allow organisms to switch prey if one species declines, helping maintain energy flow.
💡 Hint
Alternative pathways
Question
Explain why top predators usually have small populations.
Answer
There is less energy and biomass available at higher trophic levels, so fewer large consumers can be supported and they often require large territories.
💡 Hint
Less energy supports fewer
Question
Outline one way a complex food web can increase resilience.
Answer
If one prey species declines, consumers may switch to alternative prey, allowing energy flow to continue.
💡 Hint
Alternative prey
Question
Explain why food chains are short.
Answer
Energy decreases at each trophic transfer due to inefficient transfer and heat loss, limiting the number of levels.
💡 Hint
Energy loss
Question
In a food web diagram, what do arrows represent?
Answer
Arrows represent the direction of energy flow from the organism eaten to the consumer.
💡 Hint
Food → eater
Question
In food webs, arrows represent what?
Answer
The direction of energy flow from the organism eaten to the consumer.
💡 Hint
Food → eater
Question
State two markworthy points to explain short food chain length.
Answer
Energy transfers are inefficient with heat loss, and less energy/biomass is available at higher trophic levels to support additional levels.
💡 Hint
Heat loss + less available
Question
State a typical maximum length of many food chains.
Answer
Often 4 to 5 trophic levels from producers to top predators.
💡 Hint
4–5 levels
Question
State one limitation of food webs as models.
Answer
Food webs may not show population sizes, strength of interactions, or seasonal changes, so they simplify real ecosystems.
💡 Hint
Simplified model
Question
Describe the general pattern in biomass and numbers up a food chain.
Answer
Biomass and numbers generally decrease at higher trophic levels because less energy is available to build new biomass.
💡 Hint
Less at the top
Read the notes
Full study notes for Food webs
Topic 2.4 hub
Food chains & webs and trophic levels
More from Topic 2.4
All flashcards in this topic
ESS exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free