Non-membranous organelles are not isolated from the cytosol because they lack a surrounding lipid membrane. Without a barrier, these structures—such as ribosomes, proteasomes, and components of the cytoskeleton—reside directly in the cytosol and can exchange molecules, ions, and information with the cytosolic environment immediately. This contrasts with membranous organelles (like mitochondria, ER, Golgi, lysosomes, and the nucleus), whose membranes create separate internal compartments and regulate what enters or leaves. So the lack of a membrane means they remain in direct contact with the cytosol, making the statement true.

Classification into four primary tissue types defines how we categorize the tissues that form organs and body structures. The four main categories are epithelial, connective, muscle, and nervous tissue, and this grouping is the foundational way we describe tissue structure and function in anatomy and physiology. The statement that there are three primary tissue types would miss one of these essential categories, so it isn’t correct. The fact that epithelial tissue lacks vascularization describes a property of a specific tissue type, not the count or arrangement of primary tissue types as a group. And while it’s true that all tissues are composed of cells, that’s a general cell-theory point and doesn’t directly address how many primary tissue types exist. So the four-tissue classification best captures what’s being asked about primary tissue types.

Epidermal turnover and shedding timing. New keratinocytes originate in the deepest layer, move up through the epidermis, and become corneocytes in the outermost stratum. Once they reach the stratum corneum, they remain there for about two weeks before desquamation replaces them. This two-week dwell time fits with the overall roughly one-month cycle of epidermal renewal. So, the most accurate duration is about two weeks.

Dendrites are the input arms of a neuron, designed to receive signals from other neurons or sensory receptors. Their branched structure increases surface area for synaptic contacts, which is why they’re described as branches off of the cell body. They don’t carry outgoing messages—that’s the axon’s job. The nucleus sits in the cell body, not in the dendrites, and ventricles are lined by ependymal cells, not dendrites. So describing dendrites as branches off the cell body best matches their form and role in neuronal communication.