Please i need someone to answer this for me. its urgent A scientist is trying to determine the age of a rock layer in O points a canyon using Uranium-234, an isotope of Uranium. It has a half-life of about 2,000 years. There originally was 400 radioactive atoms of Uranium-234. If the rock layer tested has 100 radioactive atoms of U-234 left, how many half lives have passed AND how old is the rock layer?

Ry was studying two populations of the same species of lizards. one population lived on an island and the other lived on the mainland. both populations were affected by a hurricane that hit the island and the mainland with equal force. a year later, henry was testing the gene frequency and saw a decrease in genetic variation in the island species, but not in the mainland species. which best describes a conclusion he might have reached? gene flow greatly affects small populations, but large populations can recover. genetic drift greatly affects small populations, but large populations can recover. gene flow greatly affects large populations, but small populations can recover. genetic drift greatly affects large populations, but small populations can recover.

Lumps of iron and manganese ore called can be harvested from the seafloor near underwater volcanoes.

The genetic code is essentially the same for all organisms. based on this information, one can logically assume which of the following statements to be correct? a. dna was the first genetic material. b. the same codons in different organisms translate into the different amino acids. c. different organisms have different numbers of different types of amino acids. d. a gene from an organism can theoretically be expressed by any other organism. e. all organisms have experienced convergent evolution.