What is the inner layer of cells that forms the gut and respiratory system in animals?

endoderm

blastula

mesoderm

ectoderm

The correct answer is: Endoderm

en·do·derm

the innermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the lining of the gut and associated structures.

blas·tu·la

an animal embryo at the early stage of development when it is a hollow ball of cells.

mes·o·derm

the middle layer of an embryo in early development, between the endoderm and ectoderm.

ec·to·derm

the outermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the epidermis and nerve tissue.

Hope this helped you! :3

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

b.