Hydrogen peroxide is an example of a reactive oxygen species, made as a byproduct of metabolism. Peroxisomes use the enzyme catalase to catalyze the following reaction: . Hydrogen peroxide can be toxic to a cell if it builds up, thus converting it to harmless substances like water and oxygen gas is an important metabolic function of peroxisomes. Also, note that the breakdown of fatty acids (beta oxidation) occurs in both peroxisomes and mitochondria. Proteins, carbohydrates, and nucleic acids are broken down by the lysosome.

One of the functions of the liver is to detoxify certain substances such as alcohol, lactic acid, and drugs. Since the smooth endoplasmic reticulum plays an important role in detoxification, liver cells contain extensive smooth endoplasmic reticula. The process of forming glycoproteins is carried out by the rough endoplasmic reticulum, and to some extent, the Golgi apparatus.

The golgi apparatus collects, packages and distributes proteins to the locations where they are used. Proteins are always synthesized on ribosomes, which can either be floating in the cytosol, or on the rough endoplasmic reticulum. The smooth endoplasmic reticulum's functions include synthesis of lipids, and detoxification of substances. Lysosomes contain hydrolytic enzymes which break down macromolecules.

Lysosomes are membrane-bound organelles that contain digestive enzymes which break down all four types of macromolecules. The mitochondria is responsible for synthesis of the majority of the cell's energy in the form of ATP. The cytoskeleton maintains cell shape and provides a "freeway" for transporting substances within the cell. Flagella are proteinaceous structures that aid in cell motility.

Cell theory consists of three statements: all organisms considered to be alive are made of cells, the cell is the simplest unit of a living thing, and all cells arise from other live cells. Thus, the idea that cells arise spontaneously is not part of cell theory.

This question requires the knowledge that several biological substrates come in enantiomer forms (think of them as your right and left hands). Effectively these molecules come in two mirror/opposite configurations. Having the right configuration or shape is crucial for enzymes to catalyze reactions due to highly shape-specific bnding sites on substrate molecules.  Thus, the correct answer to this qustion is "enzymes are highly specific on shape in order to carry out a reaction." The other answer choices, except "the cell has evolved to prefer a particular enantiomer becuase it is more abundant," do not allude to this underlying concept of  why cells need a particualr enantiomeritic form/shape in order to carry out a reaction and are not correct. Last, enantiomers typically appear in similar oncentrations due to equal potential energies; therefore, it is unlikely and incorrect to expect the cell to develop an evolutionary preference based upon abundance.   

The plant central vacuole is a membrane bound organelle containing water and other enzymes. The central vacuole functions as a storage space in the center of the plant cell, and is responsible for many functions including digestion, isolating harmful materials, maintaining internal hydrostatic pressure (turgor), storage of water and small molecules, cell rigidity, and more. Aerobic respiration occurs in the mitochondria, where:

The tail, terminal disc, and most mitochondria are found near the rear of the sperm cell (in order to facilitate movement). The acrosome is a cap-like organelle (derived from the Golgi apparatus) that develops over the anterior half of the head in the sperm cells of many animals. The acrosome contains digestive enzymes which allows the break down of the outer membrane of the ovum (zona pellucida). In short, the acrosome is located at the head of the sperm cell and allows penetration of the egg cell.

Lysosomes serve as the "clean-up" crew in the cell, digesting excess proteins and lipids in the cell and breaking them down into smaller molecules.  Lysosomes do not produce messenger RNA, which is produced in transcription byDNA.  Ribosomes synthesize proteins, and the Golgi Apparatus sorts and ships proteins.

The flagellum (plural flagella) is the whip-like structure on the end of a human sperm cell that propels it forward.  Cilia are the hair-like structures on membranes on cells that aid in movement.  Smooth endoplasmic reticulum (ER) is the organelle involved in synthesizing lipids and detoxifying substances.  Cytoplasm is the jelly-like substance throughout the cell.