Cycles of Matter in Nature: Water, Carbon, and Nitrogen

The video lesson for Grade 7 covers the cycles of matter, focusing on the water, carbon, oxygen, and nitrogen cycles. It explains the processes involved in each cycle, such as evaporation, condensation, and precipitation in the water cycle, and photosynthesis and decomposition in the carbon and oxygen cycles. The nitrogen cycle is detailed with emphasis on nitrogen fixation and denitrification. The video also discusses the impact of human activities on these cycles and includes concept checks to reinforce learning.

What is the term for a series of events that are regularly repeated in the same order?

• Routine

• Sequence

• Pattern

• Cycle

Which process in the water cycle involves water vapor cooling and forming liquid droplets?

• Evaporation

• Condensation

• Sublimation

• Precipitation

How do plants contribute to the oxygen cycle?

• By releasing carbon dioxide

• By absorbing oxygen

• By producing oxygen through photosynthesis

• By consuming carbon dioxide

What happens to carbon dioxide levels when forests are cleared?

• They fluctuate

• They decrease

• They remain the same

• They increase

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

• To release nitrogen gas

• To fix nitrogen into a usable form

• To consume nitrogen

• To decompose organic matter

Which plants are known for having nodules that assist in nitrogen fixation?

• Cacti

• Mosses

• Legumes

• Ferns

Why is nitrogen essential for living organisms?

• It is used to make vitamins

• It is used to make fats

• It is used to make proteins

• It is used to make carbohydrates

In what form is nitrogen most commonly found in the atmosphere?

• Free nitrogen

• Nitrogen oxides

• Combined nitrogen

• Nitrogen compounds

How does the nitrogen cycle differ from the carbon and oxygen cycles?

• Nitrogen is not essential for life

• Nitrogen is available through the soil

• Nitrogen is only found in water

• Nitrogen is absorbed from the air

What is the process called when bacteria release free nitrogen back into the air?

• Ammonification

• Nitrogen fixation

• Denitrification

• Nitrification