If relatively small carbonaceous chondrites from space were a significant source of Earthʹs original amino acids, then which two of these would have been most important in permitting their organic materials to survive impact with Earth?

I. Carbonaceous chondrites must contain no D-amino acids.

II. Earthʹs early atmosphere must have had little free oxygen.

III. The chondrites must have arrived on Earth before 4.2 billion years ago.

IV. Earthʹs early atmosphere must have been dense enough to dramatically slow the chondrites before they impacted.

V. The chondrites must have impacted land, rather than a large body of water.

#Question id: 5565

#SCPH28 | Zoology

Among these choices, the largest cell involved in frog reproduction is ________.

#Question id: 5566

#SCPH01 Biochemistry

In some rare salamander species, all individuals are females. Reproduction relies on those females having access to sperm from males of another species. However, the resulting embryos receive no genetic contribution from the males. Why do you think sperm are necessary for reproduction?

#Question id: 5566

#I Life Science/ Life Sciences Group – I-V

In some rare salamander species, all individuals are females. Reproduction relies on those females having access to sperm from males of another species. However, the resulting embryos receive no genetic contribution from the males. Why do you think sperm are necessary for reproduction?

#Question id: 5566

#SCPH06 I Botany

In some rare salamander species, all individuals are females. Reproduction relies on those females having access to sperm from males of another species. However, the resulting embryos receive no genetic contribution from the males. Why do you think sperm are necessary for reproduction?

#Question id: 5566

#SCPH28 | Zoology

In some rare salamander species, all individuals are females. Reproduction relies on those females having access to sperm from males of another species. However, the resulting embryos receive no genetic contribution from the males. Why do you think sperm are necessary for reproduction?

#Question id: 5567

#SCPH01 Biochemistry

The cortical reaction of sea urchin eggs functions directly in ________.