Alkylating agents are electrophilic chemicals which readily add alkyl groups to various positions on nucleic acids. A common example is:

#Question id: 5016

#SCPH28 | Zoology

Approximately how far back in time does the fossil record extend?

#Question id: 5017

#SCPH06 I Botany

Arrange these events from earliest to most recent.

1.  emission of lava in what is now Siberia at time of Permian extinctions

2.  emission of lava that solidified at the same time as iron-bearing terrestrial rocks began to rust

3.  emission of lava that solidified at the same time as rusted iron precipitated from seawater

4.  emission of lava in what is now India at time of Cretaceous extinctions

#Question id: 5017

#SCPH28 | Zoology

Arrange these events from earliest to most recent.

1.  emission of lava in what is now Siberia at time of Permian extinctions

2.  emission of lava that solidified at the same time as iron-bearing terrestrial rocks began to rust

3.  emission of lava that solidified at the same time as rusted iron precipitated from seawater

4.  emission of lava in what is now India at time of Cretaceous extinctions

#Question id: 5018

#SCPH06 I Botany

Which event is nearest in time to the end of the period known as snowball Earth?

#Question id: 5018

#SCPH28 | Zoology

Which event is nearest in time to the end of the period known as snowball Earth?

#Question id: 5019

#SCPH06 I Botany

A major evolutionary episode that corresponds in time most closely with the formation of Pangaea was the