Under the microscope, you observe the first few cell divisions of an embryo. Instead of dividing the entire ball, the divisions are only separating the top half into smaller and smaller spheres. The bottom half appears to remain as one large cell. What is a likely explanation?
A. Gastrulation has occurred.
B. A developmental error has occurred.
C. The bottom half is the notochord.
D. It is a bird or fish embryo.
Answer: D
You might also like to view...
Food is sent along the GI tract by means of a wavelike process called ________
Fill in the blank(s) with correct word
Which of the following statements best characterizes a euphyll?
A. It differs from a lycophyll by having a branched, rather than a single, vascular system. B. It is believed to have evolved from a branch that flattened and developed photosynthetic tissue between the branches. C. It is also called a megaphyll because it is large compared to a lycophyll. D. It evolved separately from the photosynthetic appendages of moss gametophytes. E. All of the choices provided are correct.
Most nutrient absorption occurs in the ________, a major organ of the digestive system
Fill in the blank(s) with correct word
The most dangerous form of malaria is caused by
a) Plasmodium ovale. b) Plasmodium malariae. c) Plasmodium falciparum. d) Plasmodium vivax.