Bio 201 Human Anatomy and Physiology

Correct Answer:

transitional

Explanation:

Transitional epithelium is made of several layers of cells that can change shape depending on the degree of stretching. This tissue is specialized for areas that need to expand and contract, such as the urinary bladder, ureters, and part of the urethra. When relaxed, the cells appear cuboidal, but when stretched, they flatten out, allowing these organs to hold variable volumes of fluid without tearing.

Why Other Options Are Wrong:

pseudostratified

This is incorrect because pseudostratified epithelium appears to have multiple layers due to varied cell heights, but it actually has only one layer. It does not change shape with stretching and is commonly found lining the respiratory tract.

areolar

This is incorrect because areolar tissue is a type of loose connective tissue, not epithelial tissue. It provides support, elasticity, and cushioning but does not form layers of cells that change shape.

stratified squamous

This is incorrect because stratified squamous epithelium has multiple layers of flat cells. It provides protection in areas subject to friction, such as the skin and esophagus, but it does not stretch and change shape like transitional epithelium.

simple squamous

This is incorrect because simple squamous epithelium is a single layer of flat cells. It is specialized for diffusion and filtration, not for stretching.

Correct Answer:

cuticle-cortex-medulla

Explanation:

The hair shaft has three distinct layers arranged from the outside to the inside. The outermost layer is the cuticle, a protective layer of overlapping, scale-like cells that prevents damage. Beneath it lies the cortex, which makes up the bulk of the hair and contains keratin and pigment (melanin) that gives hair its color. The innermost layer is the medulla, which may be absent in very fine hair and consists of loosely packed cells and air spaces.

Why Other Options Are Wrong:

cortex-cuticle-medulla

This is incorrect because the cortex is not the outermost layer; the cuticle always surrounds the cortex.

medulla-cortex-cuticle

This is incorrect because it reverses the order. The medulla is at the core, the cortex surrounds it, and the cuticle forms the outer protective layer.

Correct Answer:

endoplasmic reticulum

Explanation:

The endoplasmic reticulum (ER) is a system of interconnected membrane-bound channels called cisternae. The rough ER, studded with ribosomes, is involved in protein synthesis and modification, while the smooth ER is responsible for lipid synthesis, detoxification, and calcium storage. Its cisternae provide a large surface area for biochemical reactions and transport of materials within the cell.

Why Other Options Are Wrong:

Golgi apparatus

This is incorrect because the Golgi apparatus also contains cisternae but is organized into stacked, flattened sacs specifically for modifying, sorting, and packaging proteins and lipids. It is not the widespread channel system found throughout the cytoplasm like the ER.

lysosomes

This is incorrect because lysosomes are membrane-bound vesicles containing digestive enzymes to break down cellular waste. They are not a system of cisternae.

ribosomes

This is incorrect because ribosomes are small, non-membranous structures that synthesize proteins. They are not channel systems and lack cisternae.

mitochondria

This is incorrect because mitochondria are double-membraned organelles that produce ATP through cellular respiration. They contain cristae, not cisternae.

Correct Answer:

dense regular

Explanation:

Dense regular connective tissue is composed of collagen fibers that are tightly packed and aligned in parallel bundles. Fibroblasts are arranged in rows between the fibers. This arrangement allows the tissue to resist tension and pulling in a single direction, making it ideal for tendons (which connect muscle to bone) and ligaments (which connect bone to bone). Its highly ordered structure provides strength but limited flexibility.

Why Other Options Are Wrong:

dense irregular

This is incorrect because dense irregular connective tissue has collagen fibers arranged irregularly in multiple directions. It provides strength in many directions, such as in the dermis of the skin, not just in one direction.

adipose

This is incorrect because adipose tissue is a loose connective tissue specialized for fat storage, cushioning, and insulation. It does not contain parallel bundles of collagen fibers or resist pulling forces.

areolar

This is incorrect because areolar tissue is a loose connective tissue with loosely arranged fibers in a gel-like matrix. It provides support, elasticity, and packing material but does not resist strong unidirectional pulling like dense regular connective tissue.

Correct Answer:

elastic

Explanation:

Elastic cartilage contains a dense network of visible elastic fibers in its matrix, making it both strong and highly flexible. This allows it to maintain shape while bending, which is essential for structures like the external ear (pinna) and the epiglottis. Elastic cartilage combines support with elasticity, making it distinct from other types of cartilage that focus more on strength or cushioning.

Why Other Options Are Wrong:

hyaline

This is incorrect because hyaline cartilage has a smooth, glassy appearance with few visible fibers. It provides support with some flexibility and is found in the nose, trachea, larynx, and at the ends of long bones.

fibro

This is incorrect because fibrocartilage contains thick bundles of collagen fibers, making it very strong and resistant to compression. It is found in intervertebral discs, pubic symphysis, and menisci, not in the external ear or epiglottis.

reticular

This is incorrect because reticular tissue is a type of connective tissue with reticular fibers forming a soft framework in lymphoid organs like the spleen and lymph nodes. It is not cartilage.

areolar

This is incorrect because areolar tissue is a loose connective tissue that provides cushioning and support under epithelial layers. It does not form cartilage and is unrelated to the ear or epiglottis.

Correct Answer:

blood

Explanation:

Blood is a connective tissue with a fluid matrix known as plasma. The fibers of blood, such as fibrin, are not usually visible unless clotting occurs. This unique composition allows blood to transport oxygen, nutrients, hormones, and waste products throughout the body. Unlike solid connective tissues such as bone or cartilage, blood’s fluid matrix enables it to circulate and perform vital roles in immunity, regulation, and homeostasis.

Why Other Options Are Wrong:

adipose

This is incorrect because adipose tissue is a loose connective tissue that stores fat in adipocytes. It has minimal matrix and no fluid component.

bone

This is incorrect because bone is a rigid connective tissue with a solid matrix composed of calcium salts and collagen fibers. Its fibers are always present and contribute to strength.

cartilage

This is incorrect because cartilage has a firm but flexible matrix with fibers like collagen and elastic visibly embedded in it. It does not have a fluid matrix like blood.

areolar

This is incorrect because areolar tissue is a loose connective tissue with visible collagen and elastic fibers scattered in a gel-like matrix. It does not have a fully fluid matrix.

Correct Answer:

pseudostratified

Explanation:

Pseudostratified epithelium is a single layer of tall cells that appear to be multilayered because their nuclei lie at different levels. Despite the appearance, all cells rest on the basement membrane. This type of epithelium often contains cilia and goblet cells, making it well-suited for lining respiratory passageways such as the trachea and bronchi. The cilia help move mucus and trapped particles out of the airways, protecting the lungs.

Why Other Options Are Wrong:

transitional

This is incorrect because transitional epithelium has multiple layers of cells that change shape depending on stretching. It is found in the urinary bladder, not in the respiratory system.

adipose

This is incorrect because adipose tissue is a connective tissue that stores fat. It does not form epithelial linings and is not related to respiratory passageways.

stratified squamous

This is incorrect because stratified squamous epithelium has multiple layers of flat surface cells. It provides protection in areas like the skin and esophagus, not mucus movement in respiratory passages.

areolar

This is incorrect because areolar tissue is a type of loose connective tissue. It serves as packing material under epithelia but is not itself a lining tissue for respiratory pathways.

Correct Answer:

stratified cuboidal

Explanation:

Stratified cuboidal epithelium is made up of two or more layers of cells, with the surface cells being cube-shaped (square in cross-section). This type of tissue provides protection and limited secretion/absorption. It is relatively rare in the body and is found in structures such as the ducts of sweat glands, mammary glands, and salivary glands. Its multiple layers make it more durable than simple cuboidal epithelium.

Why Other Options Are Wrong:

stratified squamous

This is incorrect because stratified squamous epithelium has multiple layers of cells with flattened surface cells, not square-shaped ones. It is specialized for protection in areas subject to friction.

stratified columnar

This is incorrect because stratified columnar epithelium has surface cells that are tall and column-like. It is found in limited areas such as parts of the pharynx and male urethra, not with square-shaped cells.

pseudostratified

This is incorrect because pseudostratified epithelium appears layered but is actually a single layer of cells with nuclei at varying levels. It typically has columnar-shaped cells, not cuboidal surface cells.

transitional

This is incorrect because transitional epithelium has multiple layers of cells that change shape depending on the degree of stretching. The surface cells can appear dome-shaped or flattened, but not consistently square.

Correct Answer:

stratified squamous

Explanation:

Stratified squamous epithelium is composed of multiple layers of cells, with the deepest layers being cuboidal or columnar and the surface layers flattened (squamous). This arrangement provides protection against friction, abrasion, and pathogens. It is commonly found in areas subject to wear and tear, such as the skin, mouth, esophagus, and vagina. The multiple layers make it durable, while the flat surface cells are easily shed and replaced.

Why Other Options Are Wrong:

simple squamous

This is incorrect because simple squamous epithelium is only a single layer of flat cells. It functions in diffusion and filtration, not protection through multiple layers.

pseudostratified

This is incorrect because pseudostratified epithelium appears layered but is actually a single layer with nuclei at different levels. It is often ciliated and found in the respiratory tract, not layered with flat cells on top.

transitional

This is incorrect because transitional epithelium has multiple layers of cells that change shape depending on stretching. The surface cells can look rounded or flat, but this is different from the consistently flat surface cells of stratified squamous.

adipose

This is incorrect because adipose tissue is a type of connective tissue specialized for storing fat. It is not epithelial tissue and does not have layers of flat surface cells.