Understanding the Nitrogen Cycle

The video explains the nitrogen cycle, highlighting its importance in life processes. It covers the main steps: nitrogen fixation, nitrification, and denitrification, along with assimilation and ammonification. Nitrogen is essential for proteins, cells, and DNA, and its cycle involves conversion between different forms, facilitated by bacteria and environmental factors.

What percentage of the air is made up of nitrogen gas?

• Three-fifths

• Two-fifths

• One-fifth

• Four-fifths

Why is nitrogen gas in the atmosphere difficult to use directly?

• It is too heavy

• It is too light

• It is covalently triple-bonded

• It is too cold

What enzyme do bacteria use to break nitrogen bonds during fixation?

• Lipase

• Protease

• Amylase

• Nitrogenase

Where do bacteria that fix nitrogen typically reside?

• In the soil surface

• On the leaves of plants

• In the atmosphere

• Under layers of slime on roots

Which bacteria convert ammonia to nitrite?

• Rhizobium

• Azotobacter

• Nitrosomonas and Nitrococcus

• Nitrobacter

What is the process of converting nitrite to nitrate called?

• Oxidation

• Hydrolysis

• Sublimation

• Reduction

What type of bacteria is involved in denitrification?

• Thermophilic bacteria

• Aerobic bacteria

• Anaerobic bacteria

• Photosynthetic bacteria

What happens to nitrates during denitrification?

• They are converted to ammonia

• They are converted to nitrites

• They are converted back to nitrogen gas

• They are absorbed by plants

What is the process by which plants absorb nitrates called?

• Assimilation

• Denitrification

• Ammonification

• Nitrification

What happens to organic nitrogen when an animal dies?

• It is converted to nitrite

• It is converted to nitrate

• It is converted to ammonia

• It is converted to nitrogen gas