TOPIC 1 ECOSYSTEM SCES3303 ENVIRONMENTAL BIOLOGY

1. What is a biogeochemical cycle?

• The movement of energy through living organisms

• The movement of nutrients and elements between biotic and abiotic factors

• The process of photosynthesis in plants

• The water cycle

1. What are the two main types of biogeochemical cycles?

• Water cycle and carbon cycle

• Gaseous cycles and sedimentary cycles

• Oxygen cycle and nitrogen cycle

• Phosphorus cycle and sulfur cycle

Which of the following is NOT a major element involved in biogeochemical cycles?

• Carbon

• Hydrogen

• Nitrogen

• Helium

Which biogeochemical cycle involves the process of photosynthesis?

• Carbon cycle

• Nitrogen cycle

• Water cycle

• Sulfur cycle

Why are biogeochemical cycles important for the environment?

• They create new elements essential for life.

• They ensure the sustainability of life on Earth by recycling matter.

• They destroy nutrients in the ecosystem.

• They permanently store all harmful elements.

Which process in the nitrogen cycle involves the conversion of atmospheric nitrogen (N₂) into ammonia (NH₃)?

• Nitrification

• Ammonification

• Denitrification

• Nitrogen fixation

What is the role of nitrifying bacteria in the nitrogen cycle?

• They convert ammonia into nitrites and then into nitrates.

• They convert ammonia into nitrogen gas.

• They decompose organic matter into ammonia.

• They convert nitrogen gas into ammonia.

Ammonification in the nitrogen cycle refers to the process of:

• Breakdown of organic nitrogen into ammonia

• Conversion of nitrates to nitrogen gas

• Conversion of nitrogen gas to ammonia

• Conversion of ammonia to nitrites

Which of the following organisms are involved in the process of nitrification?

• Pseudomonas and Bacillus

• Rhizobium and Azotobacter

• Nitrosomonas and Nitrobacter

• Fungi and Actinomycetes

Which of the following best describes the role of plants in the nitrogen cycle?

• They fix nitrogen directly from the atmosphere into the soil.

• They convert ammonia into nitrites.

• They release nitrogen gas into the atmosphere.

• They take up nitrates and ammonium to produce proteins and nucleic acids.