The correct answer is competitive inhibiiton by Compound A. You can gather that because Compound A's inhibitory properties were negated, the reaction rate increased. As a result, competitive inhibition by Compound A takes place since the reaction rate increases as reactant concentration increases which occurs regardless of inhibitor presence (assuming enough enzymes are present). In contrast, the concentration of reactants would be irrelevant in the case of allosteric regulation either by Compound A or an unknown compound. Enzyme Breakdown would not result in an increase of the reaction rate. 

A noncompetitive inhibitor does not directly compete with the substrate binding to the substrate-binding site of an enzyme. The inhibitor instead binds to another site on the enzyme, which alters the enzyme's affinity for its substrate; therefore, adding more substrate would not cause a change in enzymatic activity.

Hemoglobin is a protein found in red blood cells. It has a high affinity to bind to oxygen, carbon dioxide, and carbon monoxide. In the lungs, where oxygen concentrations are high, hemoglobin will bind to oxygen molecules and carry them through the blood to deliver to the cells of the body. Oxygen can then be used by these cells to gain energy through oxidative phosphorylation and the electron transport chain, which require oxygen as an electron receptor.

Though hemoglobin can bind carbon dioxide, most carbon dioxide waste is dissolved in the blood in the form of bicarbonate and carbonic acid. Hemoglobin's high affinity for carbon monoxide means that, when the gas is present in excess, it can block the binding sites for oxygen. This is the reason for the toxicity associated with carbon monoxide poisoning.

Proteins have the most diverse functions in biological systems. Their remarkable diversity in function is due to their diversity in structure. Structural proteins, such as tubulin and collagen, have a fibrous structure that aids their function. Enzymes have active sites that allow them to bind specific molecules (substrates) and enact a conformational change to facilitate chemical reactions. Signaling proteins include several types of hormones, known as peptide hormones. Protein receptors are commonly found embedded in the cell membrane and contain active sites to bind substrates, hydrophilic regions to interact with the cell environment and extracellular space, and hydrophobic regions to interact within the lipid bilayer.

Keratin is a fibrous protein found in hair, nails, and the epidermis of skin. Myosin is one of the major proteins of muscle. Trypsin is an enzyme in the small intestine that helps digest proteins. Collagen is a fibrous protein found in connective tissue, such as bone and cartilage. Fibrin is a clotting protein found in the blood in response to injury.

Collagen in skin and keratin in hair and nails provide the body with structure. Actin and myosin are found in muscle and facilitate movement. Antibodies defend the body against microbes. Numerous enzymatic proteins, such as pepsin and lipase, act as catalysts. Peptide hormones, such as insulin and oxytocin, help relay signals in the body.

Producers are always the lowest level of a trophic hierarchy, and consist of the autotrophs in the system. Organisms that feed off of producers are considered primary consumers.

In this example, the grasses are the producers. Both the rabbits and the turtles will be primary consumers.

An organism that feeds on primary consumers is considered a secondary consumer.

Autotrophs are organisms that are capable of generating biological energy from inorganic sources, such as sunlight in the case of photoautotrophs. Cyanobacteria are thought to be the prokaryotic precursor to chloroplasts through the endosymbiotic theory because they are able to perform photosynthesis. Cyanobacteria are, thus, photoautotrophs. Green algae are another type of photoautotroph.

Heterotrophs use organic materials from the environment to general energy. Animals are heterotrophs, including cows.

Saprotrophs, many of which are fungi, gain nutrients from decaying organic material. Mushrooms are saprotrophs.

Ecology is essentially the study of all the living things on the planet and their relationships with each other. Ecology can be organized into levels: population, community, ecosystem, and biosphere. A population is a group of organisms that belong to the same species, share an area, and can reproduce with each other. A community is composed of the different species that can be found in a geographical location. An ecosystem encompasses all abiotic and biotic factors in an area. The biosphere refers to those parts of the earth that are able to support and sustain life.

Within ecosystems, there is always a transfer of energy, usually from one organism to another. There is also energy transfer between abiotic and biotic factors. The caterpillar and lion are examples of consumers because they are unable to make their own food and must rely on other living organisms for energy. Consumers are subdivided into herbivores, omnivores, and carnivores. Producers are those living things in the ecosystem that generally produce energy using photosynthesis or light. Organisms that break down dead or decaying matter for energy are called decomposers. These are most likely bacteria, fungi (such as mushrooms), and some worms.