Questions

Galileo Galilei (1564-1642) was an Italian Astronomer who

1) Discovered 4 satellites of Jupiter

2) Developed Telescope

3) Discovered that the movement of pendulum produces a regular time measurement

He is Physicist, Mathematician, inventor, and philosopher Too.

An organelle called Eyespot allows some protists to detect light. It allows the cells to sense light direction and intensity and respond to it by swimming either towards the light (positive phototaxis) or away from the light (negative phototaxis).

Eyespot is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids.

Eyespot-mediated light perception helps the cells in finding an environment with optimal light conditions for photosynthesis. Eyespots are the simplest and most common "eyes" found in nature, composed of photoreceptors and areas of bright orange-red pigment granules.

Internet service providers (ISP's) emerged in the late 1980's and early 1990's.

The ARPANET was decommissioned in 1990.

By 1995, the Internet was fully commercialized in the U.S., when the NSFNet was decommissioned, removing the last restrictions on use of the Internet to carry commercial traffic.

Donna Tratt

Black Mamba

It is ABACUS.

Words formed are as below 

BUS
CAB
CUB
US