The fossil Archaeopteryx provides evidence for the evolutionary link between: MCQ with Answer and Explanation

Explanation:
The sinoatrial (SA) node, located in the right atrium, generates electrical impulses spontaneously and initiates each heartbeat, setting the rhythm. It is called the natural pacemaker. The atrioventricular (AV) node delays the impulse before it travels to the ventricles. The bundle of His and Purkinje fibers conduct the impulse through the ventricles.

Explanation:
The Lac operon in E. coli is a classic example of an inducible operon. It is normally 'off' (repressed) because a repressor protein binds to the operator, preventing transcription. However, when the inducer (allolactose, derived from lactose) is present, it binds to the repressor, inactivating it and allowing RNA polymerase to transcribe the genes needed for lactose metabolism.

Explanation:
Ecological succession is the gradual and predictable process of change in the species composition of an ecological community over time. It occurs after a disturbance (secondary succession) or on a newly formed, lifeless substrate (primary succession). The final, stable community that is in near equilibrium with the environment is called the climax community. The entire sequence of communities is called a sere.