4.3 Communities and Ecosystems

Which interaction between species is characterised by both species benefiting from the relationship?

A. Competition

B. Predation

C. Mutualism

D. Parasitism

What is the primary role of decomposers in ecosystems?

A. To consume producers

B. To recycle nutrients

C. To reduce energy flow

D. To increase biomass

Why is energy lost as heat between trophic levels?

A. Due to photosynthesis

B. Due to cellular respiration

C. Due to competition

D. Due to predation

Which factor primarily determines the length of food chains in ecosystems?

A. The number of predators

B. The availability of light

C. Energy limitations

D. The rate of decomposition

What is the role of autotrophs in converting carbon dioxide into carbohydrates?

A. Decomposition

B. Respiration

C. Photosynthesis

D. Predation

a) Define symbiosis and describe one example of a symbiotic relationship, explaining how it impacts community structure. [3]

b) Explain the role of decomposers in energy flow within an ecosystem and how they contribute to nutrient cycling. [3]

a) Discuss how competition between species can influence community structure, providing a specific example. [3]

b) Describe the carbon cycle and explain the role of autotrophs in this cycle. [3]

a) Explain the concept of trophic levels and how energy is transferred between these levels in an ecosystem. [3]

b) Discuss the significance of methane production by methanogenic archaeans and its impact on the atmosphere. [3]

a) Explain the difference between species richness and species evenness in measuring biodiversity. [3]

b) Discuss how invasive species can pose a threat to biodiversity, providing a real-world example. [4]

c) Outline the nitrogen cycle and identify the role of bacteria in this cycle. [3]

a) Describe the concept of carrying capacity in relation to logistic growth. [3]

b) Explain how energy limitations affect the length of food chains in ecosystems. [4]

c) Discuss the water cycle and the importance of this cycle in ecosystems. [3]