Cellular Biology: Structure and Transport Functions Quiz

The cell membrane, also known as the plasma membrane, is a crucial structure that surrounds the cell and controls the movement of substances in and out of the cell. It serves as the permeability barrier separating the inside from the outside of the cell.

The correct term for a bacterium that is spherical or ovoid in shape is 'coccus'. While 'bacillus' is rod-shaped, 'spirillum' is spiral-shaped, and 'vibrio' is comma-shaped. Therefore, the term 'coccus' specifically refers to bacteria with a spherical or ovoid shape.

Symporters are proteins that transport two different substances in the same direction across a cell membrane. Antiporters transport two substances in opposite directions, uniporters transport a single substance, and facilitated transporters aid in the transport of specific molecules across the cell membrane.

Periplasmic binding proteins are specifically designed to bind substances in the periplasmic space and transfer them to membrane-bound proteins for transportation across the cell membrane. The other options do not accurately describe the function of periplasmic binding proteins in bacterial cells.

Magnetosomes are intracellular organelles in certain bacteria that contain magnetic crystals of magnetite, allowing the bacteria to orient themselves along magnetic fields.

The bright-field microscope is the most commonly found microscope in elementary teaching laboratories due to its simplicity and cost-effectiveness for basic microscopy needs.

The answer to this question involves the ability of a microscope to distinguish between two closely spaced objects. The resolution of a microscope determines the minimum distance at which two objects can still be observed as separate entities.

Phase-contrast microscopes are commonly used in biology to visualize unstained living cells. Electron microscopes are used for ultra-high resolution imaging, fluorescence microscopes use fluorophores to label specific structures, and confocal microscopes can image specific depths of a sample.

Confocal scanning laser microscopes use a pinhole to select a specific focal plane, allowing the generation of a 3D image by scanning the plane of light. Fluorescence, electron, and phase contrast microscopes do not have this specific functionality.

Scanning electron microscopy utilizes an electron beam to scan the surface of a specimen coated with a heavy metal, allowing for detailed imaging and analysis.

Bacterial motility using flagella is the most common mode of movement among bacteria. Flagella are whip-like appendages that bacteria use to propel themselves through liquids.

Lysozyme is known for degrading the peptidoglycan layer of bacterial cell walls, making it an important component of the body's immune system defense against bacterial infections.

Endotoxins are a type of lipopolysaccharide (LPS) found in the outer membrane of Gram-negative bacteria. They are not composed of proteins, carbohydrates, or nucleic acids.

LPS, or lipopolysaccharides, are large molecules located on the outer leaf of the outer membrane of gram-negative bacteria.

In Gram-negative cells, the periplasm is the space located between the inner and outer cell membranes. Proteins found in the periplasm typically fulfill functions related to transport, signaling, and protection. While enzymes involved in DNA replication, proteins involved in photosynthesis, and ribosomal proteins are essential for other cellular processes, they are not specifically localized to the periplasm of Gram-negative cells.

Flagella are composed of flagellin protein subunits, not actin, collagen, or keratin.

The correct term for flagella sticking out uniformly around the cell is peritrichous. Monotrichous refers to a single flagellum at one pole, lophotrichous to multiple flagella at one pole, and amphitrichous to a single flagellum at each pole.

Chemotaxis is the movement of a cell or organism in response to a chemical stimulus. Osmosis is the movement of water molecules across a semipermeable membrane. Phagocytosis is the process by which cells engulf and digest particles. Cytokinesis is the division of the cytoplasm after cell division.

Tumbling in bacteria is in response to a reverse in the direction of flagellar rotation, allowing the bacterium to change its direction of movement.

Pili and fimbriae are hair-like structures found on the surface of bacteria that are involved in processes such as attachment to surfaces and motility. They do not play a role in protein synthesis, cell wall synthesis, or energy production.

Magnetosomes are membrane-bound organelles containing magnetic crystals that allow bacteria to align with Earth's magnetic field. The incorrect options do not accurately describe the crystal particles found in bacterial cells.

Glycogen and PHB granules are polymers that serve as carbon storage inclusions in cells, providing a readily accessible source of energy when needed.

Small acid-soluble proteins in bacterial endospores serve as a vital source of carbon and energy during the germination and outgrowth process, aiding in the spore's survival and growth.