Chapter 19, Sections 1 & 2

Explanation
Living things in the environment are referred to as biotic factors, while non-living things are referred to as abiotic factors. Biotic factors include all living organisms such as plants, animals, fungi, and bacteria, which interact with each other and affect the ecosystem. Abiotic factors, on the other hand, include non-living components such as sunlight, temperature, water, air, soil, and minerals, which also play a crucial role in shaping the environment and influencing the distribution and abundance of organisms.

Explanation
Soil is considered an abiotic factor because it is non-living and does not come from a living organism. It is a natural resource that consists of minerals, organic matter, water, and air. Soil plays a crucial role in supporting plant growth by providing nutrients, anchorage, and a medium for root development. It also acts as a habitat for various microorganisms and contributes to the overall ecosystem functioning.

Explanation
If water is polluted, it can have a cascading effect on other elements of the environment. Polluted water can seep into the soil, contaminating it and making it unsuitable for agriculture or other purposes. It can also evaporate and contribute to air pollution, affecting the quality of the air we breathe. Additionally, polluted water can disrupt the natural balance of ecosystems, leading to changes in climate patterns. Therefore, all of the above options - soil, air, and climate - can be affected when water is polluted.

Explanation
The water cycle involves the continuous movement of water on Earth through processes such as evaporation, precipitation, and transpiration. Water evaporates from bodies of water and land surfaces, forms clouds, and eventually falls back to Earth as precipitation. Transpiration is the process by which water is released from plants into the atmosphere. This cycle is crucial for the distribution and availability of water on Earth.

Explanation
A plant is a biotic factor because it is a living organism that interacts with other living organisms in an ecosystem. Biotic factors are the living components of an ecosystem, including plants, animals, and microorganisms. They play a crucial role in the functioning of ecosystems and contribute to the overall biodiversity and balance of the ecosystem.

Explanation
Nitrogen fixation is the process by which atmospheric nitrogen is converted into a usable form by certain bacteria. During this process, the nitrogen atoms are separated and combined with other elements to form compounds that can be used by plants and other organisms. This is necessary because atmospheric nitrogen is in a form that cannot be directly utilized by most organisms. Therefore, the correct answer is fixation.

Explanation
Chemicals would not make soil more fertile because they can have harmful effects on the soil's composition and nutrient balance. Chemicals such as pesticides and herbicides can kill beneficial microorganisms and insects that contribute to soil fertility. Additionally, excessive use of chemicals can lead to soil erosion and contamination, further degrading its fertility. Therefore, it is important to minimize the use of chemicals and opt for organic and sustainable farming practices to maintain and improve soil fertility.

Explanation
Burning fossil fuels would add excess carbon to the environment. Fossil fuels, such as coal, oil, and natural gas, contain carbon that has been stored underground for millions of years. When these fuels are burned for energy, carbon dioxide is released into the atmosphere, contributing to the greenhouse effect and climate change. This release of excess carbon into the environment is harmful and unsustainable.

Explanation
The term "human footprint" refers to the impact that humans have on the environment. It encompasses various activities and practices that contribute to environmental degradation, such as pollution, deforestation, and resource depletion. By using the term "human footprint" to represent "your impact on the environment," the answer accurately reflects the concept of how human actions affect the natural world.

Explanation
Nitrogen makes up the largest percentage of the atmosphere, accounting for about 78%. Oxygen is the second most abundant gas, comprising about 21% of the atmosphere. Water vapor and carbon dioxide are present in much smaller amounts.