Pakistan MCQs

Sensory receptors convert one form of stimulus energy, such as light, pressure, or chemicals, into electrical signals the nervous system can interpret.

Nerve signals are fast and precise, making them suitable for immediate responses such as withdrawal, escape, and coordinated movement.

Cones are photoreceptors that detect different wavelengths of light, allowing color vision where multiple cone types are present.

Thyroid hormones are essential for amphibian metamorphosis and vertebrate development. Deficiency can delay or prevent normal transformation.

Resting membrane potential depends on unequal ion distribution and selective membrane permeability. Sodium-potassium pumps help maintain these gradients.

Hormones often travel through blood or body fluids and can produce longer-lasting effects than brief nerve impulses. Their effects depend on target cell receptors.

Mechanosensory systems such as the lateral line detect environmental changes at a distance, improving survival in aquatic habitats.

Adrenaline from the adrenal medulla prepares the body for emergency action by increasing heart rate, airway dilation, and energy mobilization.

Action potentials involve voltage-gated ion channels that change sodium and potassium movement across the axon membrane. This produces a traveling electrical signal.

Sensory receptors are specialized for particular stimulus types. Photoreceptors respond to light because their molecules and membranes are adapted for that energy form.

All sensory receptors detect specific internal or external stimuli and begin signaling pathways that inform the nervous system.

Glucocorticoids such as cortisol support prolonged stress responses by mobilizing energy and modifying immune activity. They act more slowly than adrenaline.