General Biology Quiz

Calcium ions are released upon fertilization, triggering a wave of metabolic activity in the egg, including increased respiration and protein synthesis.

Thermogenin present in the mitochondria of brown adipose (fat) cells form an alternate channel for protons, disrupting the formation of the proton gradient and uncoupling proton passage from ATP formation. The energy that normally would synthesize ATP is instead released as heat—the needs of hibernating animals. Rerouting ATP formation to release heat is called thermogenesis.

Warm-blooded animals (endotherms) include mammals and birds. Among the choices, the bat is a mammal and therefore warm-blooded.

The monosaccharides glucose and galactose enter intestinal mucosa cells by active transport, whereas fructose enters by facilitated diffusion.

The epithelial cells of intestinal mucosa manufacture and secrete disaccharidases and peptidases. These enzymes are not released into the lumen of intestine but remain closely associated with the microvilli of the epithelial cells.

Initiation of heart beat may be by extrinsic nerves (neurogenic) as in many adult arthropods, or by an internal pacemaker (myogenic) as in vertebrates.

Gas exchange in the alveoli occurs via simple diffusion, where oxygen moves from an area of higher partial pressure in the alveoli to lower partial pressure in the blood, and carbon dioxide moves in the opposite direction.

While chewing breaks down food physically, the question likely refers to the mechanical breakdown of tough fibrous components in meat, which are primarily muscle tissues. Breaking these fibers increases the surface area for digestive enzymes.

Rotifera is a phylum of microscopic aquatic invertebrates, the wheel animalcules-widely distributed usually in fresh water.

Reflex acquired is conditioned reflex. It is attained by training in which the cerebral cortex is an essential part of the neural mechanism. Thus conditioned is not inborn or inherited.

Nonsteroid hormones (like peptide or amino acid-derived hormones) are water-soluble and cannot cross the cell membrane, so they bind to surface receptors and trigger secondary messengers like cAMP. Steroid hormones are lipid-soluble and act directly on intracellular receptors.