Pakistan MCQs

Ligaments are connective tissues that stabilize joints by linking bones to other bones. Tendons connect muscles to bones.

Some amphibians have strong regenerative ability, including limb regeneration. This involves coordinated growth, nerves, and tissues rather than simple wound closure.

Nerve impulses travel rapidly along specific pathways and act on targeted cells. Endocrine signals are often slower and distributed through blood or body fluids.

Skeletons help support body weight and maintain posture. This is separate from digestion, excretion, or immune memory.

Bones serve as levers and joints as fulcrums. Skeletal muscles provide the force for movement by contracting and pulling on bones.

Posture is maintained by skeletal support plus continuous or reflex muscle activity. Bones alone cannot hold normal posture without muscular control.

Chemical synapses depend on neurotransmitter release from the presynaptic neuron. Without release, the next neuron or effector receives little or no signal.

Earthworms move when circular muscles lengthen segments and longitudinal muscles shorten them. The hydrostatic skeleton gives resistance for these shape changes.

Amoeboid movement uses cytoplasmic streaming and pseudopodia rather than muscle fibers. It is a cellular locomotion mechanism.

Muscular systems are not required in unicellular or very small organisms. Protozoans and many cells move by cilia, flagella, pseudopodia, or cytoplasmic streaming.

In a withdrawal reflex, receptors detect heat or pain, neurons carry signals, and skeletal muscles act as effectors to move the limb away.

Keratin is a tough structural protein in hair, nails, claws, and epidermis. It strengthens integumentary derivatives and improves protection.