Question

question: 10
homologous structures may have similar ancestry but not the same function. analogous structures have different evolutionary ancestry, but the same function.
which of these pairs of structures are most likely analogous structures and why?
a. human ear muscles and horse ear muscles, because humans cant move their ears and horses can
b. flippers of penguins and wings of birds, because penguins cant fly and birds can
c. insects wings and birds wings, because both organisms use them for flying
d. arms of humans and wings of bats, because the bones are similar
a scientist is trying to determine the nature of a contaminant in her lab cultures. she conducts an analysis in which she finds that the contaminant in her cultures has the following characteristics:

• its genetic code is double - stranded dna.
• it also contains rna and changes over time.

using the information in the table to compare and contrast the characteristics of the possible contaminants in the scientists cell cultures, what is the most likely contaminant in the scientists cell cultures, and why?
a. both viruses and eukaryotic cells, because they both have linear double - stranded dna.
b. eukaryotic cells, because they have linear, double - stranded dna as well as rna in the cytoplasm.
c. both viruses and prokaryotic cells, because they have double - stranded dna and they both change over time.
d. both prokaryotic cells and eukaryotic cells, because they both have double - stranded dna as well as rna in their cytoplasm.

Explanation:

For the first part:

• Analogous structures have different evolutionary ancestry but the same function. Insects' wings and birds' wings have different evolutionary origins (insects are invertebrates, birds are vertebrates) but both are used for flying.

For the second part:

• Viruses can have double - stranded DNA (as per the table, virus genetic code may be DNA or RNA, and can have double - stranded nucleic acids). Prokaryotic cells have double - stranded DNA only. Eukaryotic cells have double - stranded DNA only. But the contaminant has double - stranded DNA and also contains RNA. Prokaryotic cells have DNA in the cytoplasm (nucleoid region) and may have some RNA in the cytoplasm (for processes like translation). Viruses can have RNA as part of their genetic material (but the key here is that prokaryotic cells have DNA (double - stranded) and also have RNA in the cytoplasm for normal cellular processes like gene expression (transcription of DNA to RNA). Eukaryotic cells have DNA in the nucleus (double - stranded) and RNA in the cytoplasm, but the table shows eukaryotic cells have DNA only as genetic code. Viruses' genetic code may be DNA or RNA, but the fact that the contaminant has double - stranded DNA (like prokaryotes and eukaryotes) and RNA (prokaryotes have RNA in cytoplasm for normal cell function, eukaryotes have RNA in cytoplasm but genetic code is DNA only, viruses' genetic code may be RNA but the double - stranded DNA part for virus is only'may be').

Answer:

First question: C. insects' wings and birds' wings, because both organisms use them for flying
Second question: D. Both prokaryotic cells and eukaryotic cells, because they both have double - stranded DNA as well as RNA in their cytoplasm.