A cell does not want to waste energy synthesizing the amino acid arginine if arginine is present in its diet. Therefore, when arginine is present, it activates a repressor protein to prevent transcription of genes that code for enzyme to make arginine. This is an example of what type of regulation?

#Question id: 4935

#SCPH28 | Zoology

Which gas was least abundant in Earthʹs early atmosphere, prior to 2 billion years ago?

#Question id: 4940

#SCPH06 I Botany

In their laboratory simulations of the early Earth, Miller and Urey observed the abiotic synthesis of

#Question id: 4940

#SCPH28 | Zoology

In their laboratory simulations of the early Earth, Miller and Urey observed the abiotic synthesis of

#Question id: 4941

#SCPH06 I Botany

Which of the factors below weaken the hypothesis of abiotic synthesis of organic monomers in early Earthʹs atmosphere?

1.  the relatively short time between intense meteor bombardment and appearance of the first life forms

2.  the lack of experimental evidence that organic monomers can form by abiotic synthesis

3.  Uncertainty about which gases comprised early Earthʹs atmosphere

#Question id: 4941

#SCPH28 | Zoology

Which of the factors below weaken the hypothesis of abiotic synthesis of organic monomers in early Earthʹs atmosphere?

1.  the relatively short time between intense meteor bombardment and appearance of the first life forms

2.  the lack of experimental evidence that organic monomers can form by abiotic synthesis

3.  Uncertainty about which gases comprised early Earthʹs atmosphere

#Question id: 4942

#SCPH06 I Botany

Which of the following has not yet been synthesized in laboratory experiments studying the origin of life?