Lesson 1.4 Earth's Subsystems

Explanation
The statement "The earth is a closed system" is true. A closed system refers to a system that does not exchange matter with its surroundings, but it can exchange energy. In the case of the earth, it is considered a closed system because although it receives energy from the sun in the form of sunlight, it does not exchange matter with outer space. The earth's atmosphere acts as a barrier, preventing the exchange of matter with the rest of the universe. However, energy in the form of heat and light can still enter and leave the earth's system.

Explanation
Oxygen is not the most abundant element present in the atmosphere. The most abundant element in the atmosphere is nitrogen, which makes up about 78% of the Earth's atmosphere. Oxygen is the second most abundant element, making up about 21% of the atmosphere.

Explanation
The geosphere refers to the solid Earth, including the rocks, minerals, and landforms. It does not include life forms or organic matter, which are part of the biosphere. Therefore, the given statement is false.

Explanation
The given statement is false because about 71% of the Earth's surface is covered with liquid water, not 30%. This includes oceans, seas, lakes, rivers, and other bodies of water. The remaining percentage consists of landmasses and polar ice caps.

Explanation
Biogeochemical cycles, including the hydrologic and carbon cycles, demonstrate the interconnectedness and interaction of Earth's four subsystems: the atmosphere, hydrosphere, lithosphere, and biosphere. These cycles involve the movement and transformation of elements and compounds, such as water and carbon, through different Earth compartments. The hydrologic cycle involves the continuous circulation of water between the atmosphere, land, and oceans, while the carbon cycle involves the exchange of carbon dioxide between the atmosphere, plants, animals, and the ocean. These cycles are essential for maintaining the balance of nutrients and energy on Earth, highlighting the interdependence of Earth's subsystems.

Explanation
Oceans act as sinks of carbon dioxide because they have the ability to absorb and store large amounts of this greenhouse gas. When carbon dioxide is released into the atmosphere through human activities such as burning fossil fuels, a portion of it is absorbed by the oceans. This process helps to regulate the levels of carbon dioxide in the atmosphere and mitigate the impacts of climate change. Additionally, the absorbed carbon dioxide can react with seawater to form carbonic acid, leading to ocean acidification, which has detrimental effects on marine life.

Explanation
A closed system does not allow the exchange of matter and energy. In a closed system, neither matter nor energy can enter or leave the system. This means that the total amount of matter and energy within the system remains constant.

Explanation
Carbon is stored in the geosphere as coal and oil deposits. Coal and oil are formed from the remains of ancient plants and animals that have been buried and subjected to high pressure and temperature over millions of years. This process, known as fossilization, converts the organic matter into carbon-rich substances. These coal and oil deposits are found deep within the Earth's crust and can be extracted for various purposes. Therefore, the statement that carbon is stored in the geosphere as coal and oil deposits is true.

Explanation
After the eruption of Mt. Pinatubo in 1991, all four subsystems - Atmosphere, Hydrosphere, Geosphere, and Biosphere - were affected. The eruption released a large amount of volcanic ash and gases into the atmosphere, causing a temporary cooling effect on the climate. The ash also affected the hydrosphere by polluting rivers and lakes, and the gases dissolved in rainwater caused acid rain. The geosphere was directly impacted by the eruption, with the deposition of ash and the formation of new volcanic landforms. Finally, the biosphere was affected as the ash and gases disrupted ecosystems, causing damage to plants and animals.