WATER CYCLE, CARBON OR NITROGEN CYCLE

🌊 Water Cycle

Band 7 Answer
The diagram illustrates the stages of the water cycle, which is a continuous natural process. Overall, it shows how water circulates from the earth’s surface to the atmosphere and back again.

The cycle begins when heat from the sun causes water from oceans, rivers, and lakes to evaporate. The vapor rises and condenses into clouds. Once the clouds become saturated, precipitation occurs in the form of rain or snow. This water either flows into rivers and seas or infiltrates into the ground to form underground reserves. Eventually, surface runoff and groundwater return to the ocean, allowing the cycle to restart.

This process is essential for maintaining life on earth as it ensures a constant supply of fresh water.

Band 8 Answer
The diagram presents the water cycle, a self-sustaining process in which water moves between the earth’s surface and the atmosphere. Overall, it is a closed system driven primarily by solar energy, ensuring the continuous renewal of fresh water.

The process begins when heat from the sun triggers evaporation from large water bodies such as seas, rivers, and lakes. Water vapor ascends into the atmosphere, where it undergoes condensation, forming dense clouds. When these clouds reach saturation, precipitation takes place in the form of rainfall, hail, or snow.

Following this stage, water either travels as surface runoff into rivers and oceans or penetrates the soil, replenishing groundwater reserves. Some of this infiltrated water may eventually flow into rivers, while a portion is absorbed by plants and released again through transpiration. Ultimately, all water finds its way back to the sea, allowing the cycle to repeat.

This recurring sequence is vital for regulating ecosystems and maintaining water availability across the planet.

🌍 Carbon Cycle

Band 7 Answer
The diagram shows the carbon cycle, which explains how carbon is exchanged between living organisms, the atmosphere, and the earth. Overall, it highlights that the cycle is continuous and influenced by both natural processes and human activity.

Carbon dioxide in the atmosphere is absorbed by plants during photosynthesis. Animals consume these plants and release carbon dioxide through respiration. When plants and animals die, decomposition returns carbon to the soil. Some of this material becomes fossil fuels over time. Human activities, such as burning fuels, release large amounts of carbon dioxide back into the atmosphere, completing the cycle.

Band 8 Answer
The diagram illustrates the carbon cycle, a complex system through which carbon circulates between the atmosphere, living organisms, the oceans, and the lithosphere. Overall, it demonstrates that carbon is constantly exchanged, with human activity significantly intensifying the process.

Initially, plants absorb carbon dioxide from the air through photosynthesis, converting it into organic matter. Animals then consume plants, releasing carbon dioxide via respiration. When organisms die, decomposers break down their remains, returning carbon to the soil. Over geological timescales, some of this carbon becomes stored as fossil fuels such as coal, oil, and gas.

Additionally, oceans act as both reservoirs and sources of carbon, absorbing large amounts of carbon dioxide while also releasing it back into the air. However, industrial activities, particularly the combustion of fossil fuels, have greatly increased atmospheric carbon dioxide, amplifying the natural cycle.

Thus, while the cycle is a natural system, human influence has accelerated it, contributing to global climate change.

🌱 Nitrogen Cycle

Band 7 Answer
The diagram describes the nitrogen cycle, which shows how nitrogen moves through the air, soil, and living organisms. Overall, it is a repeating process that maintains the balance of nitrogen in ecosystems.

Atmospheric nitrogen is first fixed by bacteria in the soil or through lightning. Plants absorb it in the form of nitrates, which are then passed to animals when they eat plants. When plants and animals die, decomposers return nitrogen to the soil. Finally, other bacteria release nitrogen gas back into the atmosphere, and the cycle continues.

Band 8 Answer
The diagram illustrates the nitrogen cycle, a crucial ecological process that recycles nitrogen between the atmosphere, soil, and living organisms. Overall, it highlights the role of microorganisms in converting nitrogen into usable forms and ensuring its constant circulation.

Initially, nitrogen gas in the atmosphere, which is inert, must be fixed by soil bacteria or by lightning, producing compounds such as nitrates. These are absorbed by plants and incorporated into proteins. Animals obtain nitrogen by consuming plants, and when they excrete waste or die, decomposers break down organic material, returning nitrogen to the soil.

From this stage, nitrifying bacteria convert ammonia into nitrites and nitrates, making them available again for plant absorption. Denitrifying bacteria, however, transform nitrates back into nitrogen gas, which re-enters the atmosphere. This completes the loop.

This natural cycle is essential for soil fertility and the survival of ecosystems, as nitrogen is a key component of proteins and DNA.

PLEASE NOTE: IMAGE SHOWN IS ONLY A SAMPLE ILLUSTRATION AND IS NOT RELATED TO THE ACTUAL ANSWERS. SAMPLE DESIGN IS TO GIVE YOU AN IDEA OF HOW THE IMAGE LOOKS