Cellular respiration is an anabolic reaction.

A. Stratified epithelia are tall, narrow cells:Stratified epithelia are defined by having multiple layers of cells, not by cell shape. While some stratified cells can be tall (columnar), they can also be cuboidal or squamous in shape, depending on the location.

B. Pseudostratified epithelia consist of at least two layers of cells stacked on top of one another:Pseudostratified epithelium appears multilayered because nuclei are at different levels, but all cells contact the basement membrane. It is not composed of multiple layers.

C. Stratified epithelia are present where protection from abrasion is important:Stratified epithelia provide multiple layers of cells, offering significant protection against mechanical stress, friction, and abrasion. This is why they are found in areas such as the skin, mouth, and esophagus.

D. Simple epithelia form impermeable barriers:Simple epithelia are composed of a single cell layer and allow for selective diffusion, absorption, or secretion rather than forming completely impermeable barriers.

A. stratum spinosum:This layer lies just above the stratum basale and is composed of keratinocytes that provide structural strength. While important for resilience, it does not contain multiple layers of dead cells.

B. stratum basale:This is the deepest epidermal layer consisting of a single row of basal cells that actively divide to form new keratinocytes. It contains living cells, not dead ones.

C. stratum corneum:The stratum corneum is the outermost layer of the epidermis, made up of up to 30 layers of flattened, dead keratinized cells. These cells provide a protective barrier against pathogens, water loss, and mechanical stress.

D. stratum granulosum:This layer lies beneath the stratum corneum and consists of keratinocytes beginning to die and fill with keratin. It does not contain as many layers as the stratum corneum and is not the thick, fully dead cell layer.