Why have scientists not found evidence for heavy bombardment of leftover asteroids and meteoroids?

One of the purposes of transcription is to produce a sequence of bases that

Why do we perceive objects as retaining their brightness under different lighting levels?

Below are the three main organs that make up the plant body. what is the main function of the structure that is identified as b in the picture above? it anchors the plant.it produces food.it absorbs nutrients.it supports the plan