Question

Which character is not the same in Aves and mammals?
A. Single system arch
B. Metanephric kidney
C. Seven cervical vertebrae
D. Homeotherms

Answer 1

In mammals, a multicellular organism occurs during the early stages of fertilization, in which two four-celled stage embryos and eight-cell stage embryos are present. They differ in the spine.

Complete answer: In mammals, there are seven cervical vertebrae, but in aves, it varies between 13 to 25 in number, but other characteristics, such as homeotherms, metanephric kidneys, single systemic arches are present in both aves and mammals. Mammals reproduce by the fusion of male and female gametes that initiate the development of new offspring. The whole process is known as fertilization. In the ampulla of the uterine tube or the oviduct, the fallopian tube possesses gametes. The fertilized egg then moves down from the fallopian tube and gets implanted to the uterus wall of the mother. Mammals are vertebrates present in the class Mammalia and in females, production of the milk occurs through the mammary glands. In the oviduct, fertilization takes place and the ova is viable till 24 hours after fertilization. During the fertilization, the fusion of gametes produces diploid zygotes. The beginning process of fertilization in all other animals and mammals are mostly the same, such as cleavage, growth and differentiation. During the process, ectoderm, outer layer, middle layer, mesoderm, inner layer, endoderm are germ layers that can be seen.
Therefore, the correct answer is option C.

Note: Activation of ovum, encounter of the spermatozoa, ova, the fusion of the sperm with the egg, capacitation or contact and acrosomal reactions or penetrations are some of the mechanisms that occur during the time of fertilization in mammals.