BIO NMDCAT

Correct: Compact bone consists of osteons and a mineralized matrix that provides great strength. A: Chondrin is found in cartilage. C: Bone has abundant extracellular matrix. D: Elastic fibers increase flexibility, not compressive strength. Concept: Structure of compact bone.

Correct: Blood vessels supply nutrients, while osteoblasts produce new bone during healing. A: Elastic cartilage is found in the ear. C: Chondrocytes are cartilage cells. D: Dense connective tissue forms tendons and ligaments. Concept: Bone repair.

Correct: Ossification is the formation of bone tissue from cartilage. A & D: Calcification and mineralization are parts of ossification but not the complete process. C: Resorption refers to bone breakdown. Concept: Bone development.

Correct: Cartilage contains chondrocytes in lacunae and lacks Haversian systems. A & B: These are features of compact bone. D: Cartilage is avascular. Concept: Microscopic comparison of cartilage and bone.

Correct: Articular cartilage provides a smooth, shock-absorbing surface at joints. A: Red blood cells are produced in bone marrow. C: Tendons attach muscles to bones. D: Mineral storage is mainly a function of bone. Concept: Function of articular cartilage.

Correct: Collagen gives bones flexibility and resistance to breaking. A: Hardness is due to mineral salts. C: Minerals are stored in bone, not collagen. D: Blood cells are produced in bone marrow. Concept: Role of collagen in bone.

Correct: Bone contains living osteocytes, blood vessels, and nerves, making it metabolically active. A: Minerals alone are non-living. C: Bone has abundant extracellular matrix. D: Bone has a remarkable capacity for repair. Concept: Characteristics of living bone tissue.

Correct: Osteoblasts beneath the periosteum deposit new bone on the outer surface, increasing bone thickness. A: Chondrocytes increase bone length. C: Osteoclasts resorb bone. D: Osteocytes mainly maintain bone tissue. Concept: Appositional growth of bone.

Correct: Chondrin gives cartilage resilience and flexibility for shock absorption. A: Mineralization makes bone rigid. C: Osteons are bone structures. D: Cartilage is avascular. Concept: Structure-function relationship of cartilage.

Correct: Hyaline cartilage is flexible and resilient, allowing structures like the nose to bend and regain shape. A: Compact bone is rigid. C: Skeletal muscle contracts rather than providing structural flexibility. D: Dense connective tissue lacks the elasticity of cartilage. Concept: Structure-function relationship of cartilage.

Correct: Bone hardness results from deposition of calcium phosphate and other mineral salts. A: Collagen provides tensile strength but not hardness alone. C: Elastic fibers increase flexibility. D: Chondrin is characteristic of cartilage. Concept: Composition of bone matrix.

Correct: Cartilage is avascular, so nutrients diffuse through the matrix, making repair slow. A: Bone is richly vascularized. B: Muscle has a good blood supply. D: Tendons receive more blood than cartilage. Concept: Vascularity and healing.

Correct: Removal of mineral salts leaves collagen fibers, making the bone flexible. A: Brittleness occurs when collagen is removed. C: Organic matrix remains intact. D: The bone can bend after decalcification. Concept: Role of inorganic and organic components of bone.

Correct: Articular cartilage provides a smooth surface for movement and absorbs shock. A: Blood cells form in bone marrow. C: Calcium is mainly stored in bone. D: Tendons attach muscles to bones. Concept: Functions of cartilage.

Correct: Bone is vascular, whereas cartilage is avascular. A: Both contain living cells. B: Both possess extracellular matrices. D: Both contribute to support, although bone is the primary supporting tissue. Concept: Comparison between bone and cartilage.

The correct option is Utilize RNA-dependent DNA polymerase to synthesize DNA from an RNA template. Retroviruses possess an RNA genome and the enzyme reverse transcriptase, which reverse-transcribes their RNA into DNA, a process essential for integrating into the host's genome.

The correct option is Gonorrhea. Untreated gonorrhea (along with Chlamydia) is a leading cause of pelvic inflammatory disease (PID), which scars the fallopian tubes and heavily predisposes women to ectopic pregnancies.

The correct option is Microtubule-associated motor proteins within the axon. The virus enters the sensory nerve endings and exploits the neuron's microtubule transport system (dynein motors) to travel retrograde up the long axon to the cell body in the ganglion for latency.

The correct option is Contain high numbers of spirochetes and are highly infectious. Secondary syphilis is marked by systemic mucocutaneous lesions (rash, mucous patches) that are laden with Treponema pallidum, making this stage extremely contagious through contact.