Ecosystems and How They Work

Energy transfer follows the 10 percent rule. Producer (13,500) -> Primary (1,350) -> Secondary (135) -> Tertiary (13.5).

Applying the 10 percent rule: Producer (5,000) -> Primary (500) -> Secondary (50).

Carnivores cannot fix atmospheric nitrogen or synthesize it from the air. They obtain necessary nitrogen compounds by consuming other organisms that have already incorporated nitrogen into their tissues.

Fossil fuels like coal and oil contain carbon, nitrogen, and sulfur impurities. When burned, these release oxides of carbon, nitrogen, and sulfur into the atmosphere.

Phosphates are limiting nutrients in aquatic ecosystems. Excess phosphate runoff causes eutrophication, leading to rapid, uncontrolled growth of algae and bacteria.

Nitrification converts ammonia into nitrates, which plants can use. Denitrification is the process where bacteria convert nitrates back into nitrogen gas, releasing it into the atmosphere.

Plants cannot absorb nitrogen gas directly from the air. They rely on nitrogen-fixing bacteria, often in soil or root nodules, to convert nitrogen gas into a usable form like ammonia or nitrates.

Unlike the carbon, nitrogen, and water cycles, the phosphorus cycle does not include a significant gaseous phase. Phosphorus primarily cycles through soil, water, and living organisms.

The nitrogen cycle involves biological processes (bacteria), atmospheric processes (lightning), and human inputs (fertilizer). Rocks are primarily associated with the phosphorus or rock cycles, not the nitrogen cycle.

Forests, the atmosphere, and the ocean are all massive natural reservoirs for carbon. Fertilizer is a human-made product, not a large-scale natural carbon reservoir.

Photosynthesis is the process by which autotrophs capture atmospheric carbon dioxide and convert it into energy-rich organic molecules like glucose.

Cellular respiration breaks down organic molecules to release energy, producing carbon dioxide as a byproduct, which is then released into the atmosphere.

Photosynthesis removes carbon from the atmosphere, and respiration returns it. These two processes are the primary drivers of the short-term biological carbon cycle.

In the hydrologic cycle, transport refers to the movement of water from one location to another, such as through atmospheric currents or surface runoff.

Organic chemistry is defined by the study of carbon-based compounds. Carbon's ability to form stable, complex chains is the basis for all known life.

According to the law of conservation of matter, the total amount of matter on Earth remains constant; it is only recycled through different forms and locations.

The law of conservation of matter states that matter cannot be created or destroyed in a chemical reaction, only rearranged.

The 10% rule in ecology states that only about 10% of the energy at one trophic level is passed on to the next level, while the rest is lost as heat.

Anaerobic respiration occurs in the absence of oxygen. Oxygen is a reactant in aerobic respiration, not a product of anaerobic processes.

Anaerobic respiration is the process of breaking down glucose without oxygen, using alternative electron acceptors like sulfates or nitrates.

In a food chain, the tertiary consumer is the organism at the top level, which eats secondary consumers.

The limiting factor principle states that too much or too little of any abiotic factor can limit or prevent the growth of a population, even if other factors are optimal.

Helium is an inert noble gas and is not a greenhouse gas. Water vapor, methane, and carbon dioxide are all potent greenhouse gases.

The Earth's atmosphere is composed of approximately 78% nitrogen, 21% oxygen, and 1% other gases.

Nitrogen makes up the vast majority of the Earth's atmosphere, accounting for about 78% of its volume.

The troposphere is the lowest layer of the atmosphere and contains the vast majority of the air mass and weather systems.

A community is defined as all the populations of different species that live and interact in a specific area.

Genetic diversity refers to the variety of genes within a population. Species, ecosystem, and functional diversity refer to broader levels of biological organization.

A population is defined as a group of individuals of the same species living in the same area at the same time. A community includes multiple species, and an ecosystem includes both living and non-living factors.

Ecology is the scientific study of interactions between organisms and their environment, including relationships between living things. While biology is the broader study of all living organisms, ecology specifically focuses on connections in nature. The spelling of 'Botony' is incorrect; it should be 'Botany' which studies plants.

The Encyclopedia of Life and similar scientific databases estimate the number of formally described species to be around 2 million. The other options are either too low or significantly overestimate the number of documented species.

A species is defined as a group of organisms that can interbreed and produce fertile offspring. Population, community, and biosphere describe larger ecological groupings.

Eukaryotic cells are characterized by having a defined nucleus and membrane-bound organelles. Prokaryotic cells lack these structures.

Prokaryotic cells are simple cells that lack a nucleus and membrane-bound organelles. They contain DNA and a cell membrane but are structurally less complex than eukaryotic cells.

Cell Theory is the fundamental scientific theory that states all living organisms are composed of cells. The other theories listed relate to physics or chemistry.

The cell is the smallest structural and functional unit of all living organisms. Atoms and molecules are smaller but are not considered alive.