AP Outline Bio Quiz Ch 25

Explanation
The biosphere is the correct answer because it refers to the layer on Earth where life is possible. It includes all living organisms and their interactions with the atmosphere, hydrosphere, and lithosphere. The biosphere extends from the highest point in the atmosphere to the deepest point in the ocean, encompassing all areas where life can exist.

Explanation
An ecosystem is a complex system that includes both living organisms (biotic components) and non-living factors (abiotic components) that interact with each other. These interactions between organisms and their environment are essential for the functioning of the ecosystem. Therefore, the correct answer is that an ecosystem contains both the living organisms and the abiotic components of the environment.

Explanation
Approximately 10% of the energy in one trophic level becomes incorporated into the next level as secondary productivity. This is due to the inefficiencies in energy transfer between trophic levels, such as energy being lost as heat or being used for metabolic processes. As energy moves up the food chain, only a small portion is transferred to the next level, resulting in a decrease in energy availability at each subsequent level.

Explanation
Herbivores are generally more numerous than carnivores because they occupy a lower trophic level in the food chain. They feed on plants, which are abundant and provide a large source of energy. This allows herbivores to reproduce and maintain larger populations compared to carnivores, who rely on consuming other animals. Additionally, herbivores often have shorter lifespans and faster reproductive rates, contributing to their higher numbers.

Explanation
This statement is false because not all food chains begin with a photosynthetic producer. Some food chains may start with a primary consumer that feeds on plants or other organisms, which are not photosynthetic producers. For example, a food chain could start with a herbivorous animal that consumes plants, and then continues with a carnivorous animal that preys on the herbivore. In this case, the food chain does not begin with a photosynthetic producer.

Explanation
This statement is true because decomposers play a crucial role in breaking down dead organic matter and recycling nutrients back into the ecosystem. They consume the remains of organisms from all trophic levels, including plants, animals, and other decomposers. This process helps to release nutrients that can be used by other organisms, ensuring the continuation of the food web and the overall functioning of the ecosystem.

Explanation
Energy recycling is not an important part of every ecosystem. While energy flow and transfer are crucial for the functioning of an ecosystem, energy recycling specifically refers to the process of reusing or repurposing energy within the system. In reality, energy in ecosystems is not recycled but rather flows through the system in a one-way direction, with energy being continuously lost as heat. Therefore, the statement is false.

Explanation
A pyramid of biomass is not based on the number of organisms at each trophic level, but rather on the total biomass (the total mass of living organisms) at each trophic level. This means that the pyramid represents the amount of energy stored in the form of biomass at each trophic level, with typically fewer organisms but greater biomass at higher trophic levels.

Explanation
The statement in the question suggests that food chains are long and involved, with at least seven or eight trophic levels. However, this statement is false. Food chains typically consist of only a few trophic levels, usually ranging from three to five. The number of trophic levels is limited because energy is lost as it moves up the food chain, and there is not enough energy available to support a large number of levels. Therefore, the correct answer is false.

Explanation
Nitrogen fixation is actually the conversion of atmospheric nitrogen gas into a form that can be used by plants, such as ammonia or nitrate. It is an essential process for the nitrogen cycle and is carried out by certain bacteria and cyanobacteria. The conversion of nitrate to nitrous oxide and nitrogen gas is not part of nitrogen fixation, but rather a different process called denitrification. Therefore, the correct answer is false.