Where is the temporalis muscle located?

Correct Answer: C

Rationale: The temporalis muscle spans the side of the head, originating from the temporal bone's fossa and inserting on the mandible, elevating it for chewing. The forehead hosts frontalis for brow movement. The neck has muscles like sternocleidomastoid for head turning. The chin area features mentalis for lip motion. Temporalis' lateral cranial position and masticatory role distinguish it, essential for jaw closure, unlike forehead, neck, or chin functions.

Correct Answer: B

Rationale: Gram-positive bacteria, with thick peptidoglycan walls, secrete potent, soluble proteins known as exotoxins into the bloodstream. These toxins, like tetanus or botulinum toxins, are released during bacterial growth, targeting specific host cells and causing diseases such as diphtheria or food poisoning. Endotoxins, conversely, are lipopolysaccharides from gram-negative bacteria's outer membranes, released upon cell lysis, not secreted. The generic term 'toxin' lacks specificity, and 'none of the above' dismisses the clear distinction. Exotoxins' solubility in plasma and their secretion mechanism highlight their role in pathogenesis, contrasting with endotoxins' structural origin, making them the precise answer for gram-positive bacterial products.

Correct Answer: D

Rationale: Animals are heterotrophs, obtaining nutrients by consuming organic matter. Bread mold, a fungus, also functions heterotrophically, secreting enzymes to break down external organic substrates like bread, absorbing the products. Seaweed, oak trees, and grass are autotrophs, using photosynthesis to synthesize food from sunlight. Bread mold's reliance on external digestion and absorption mirrors animal nutrition, unlike plants' self-production, making it the closest match in nutritive strategy, reflecting shared ecological roles as decomposers or consumers.

Correct Answer: D

Rationale: During pregnancy, the placenta forms from maternal and fetal tissues, connecting the embryo to the uterine wall. It transfers oxygen and nutrients from the mother's blood to the fetus's, removes waste, and produces hormones like progesterone to sustain pregnancy. The amnion encases the fetus in fluid, the yolk sac provides early nutrients in other species, and the fallopian tube transports eggs. The placenta's nourishing role, critical for fetal development, distinguishes it as the key gestational organ in humans.

Correct Answer: A

Rationale: Somatic motor (efferent) neurons, part of the voluntary nervous system, release acetylcholine at neuromuscular junctions to initiate skeletal muscle contraction, driving movements like lifting. Sympathetic neurons regulate involuntary functions (e.g., heart rate), not skeletal muscle. Sensory neurons transmit stimuli to the CNS, not activating muscles. 'Muscle neuron' isn't a term neurons innervate, not reside in, muscle. Somatic motor neurons' direct, voluntary control distinguishes them, essential for skeletal muscle's deliberate action, unlike autonomic or sensory roles.