Animal Development Revised Quiz

Explanation
A zygote is a diploid cell formed from the joining of a sperm and an egg. It is the initial cell that is formed during fertilization and contains the full set of chromosomes from both parents. This cell then undergoes rapid cell division and development to form an embryo.

Explanation
An animal egg provides nourishment for the embryo. This is because the embryo, which is the developing offspring, relies on the nutrients stored in the egg for its growth and development. The egg provides essential proteins, fats, and other nutrients that are necessary for the embryo to survive and develop into a fully formed animal. Without this nourishment, the embryo would not be able to grow and would not survive.

Explanation
Microlecithal or isolecithal eggs are found in mammals and mesolecithal eggs are found in amphibians.

Explanation
The last part of the sentence is true however, in isolecithal eggs the yolk is evenly distibuted so the animal pole is better seen in telolecithal eggs.

Explanation
Cleavage is a type of cell division that occurs during the early stages of embryonic development. It involves the rapid and repeated division of cells without growth in between. This process is essential for the formation of a multicellular organism from a single-celled zygote. Cleavage is a form of mitosis, where the parent cell divides into two identical daughter cells. Meiosis, on the other hand, is a type of cell division that occurs in reproductive cells, resulting in the production of gametes with half the number of chromosomes.

Explanation
After the process of cleavage, the zygote develops into a multicellular stage called the gastrula. During gastrulation, the blastula undergoes cell movement and rearrangement, forming three primary germ layers - ectoderm, endoderm, and mesoderm. These germ layers give rise to different tissues and organs in the developing organism. Therefore, the correct answer is Gastrula.

Explanation
After the morula is formed, the next stage of development is called the blastula stage. During this stage, a central cavity called the blastocoel forms within the morula. Therefore, the correct answer is Blastula.

Explanation
The types of cleavage should be switched holoblastic cleavage occurs in microlecithal cells.

Explanation
A squid is a mollusk which is a Protosome.

Explanation
The major difference between Protosomes and Deuterosomes is their type of cleavage. While Protosomes go through indeterminant cleavage, Deuterosomes go through indeterminate cleavage. This means that in Protosomes, the fate of each cell is determined early on, while in Deuterosomes, the fate of the cells is not determined until later stages of development.

Explanation
The correct answer is Microderm. Microderm is not a germ layer that develops into bodily structures and organs. The three primary germ layers that give rise to different tissues and organs during embryonic development are endoderm, ectoderm, and mesoderm. Endoderm develops into the innermost lining of organs such as the digestive tract and respiratory system. Ectoderm gives rise to the outermost layer of the skin, nervous system, and sensory organs. Mesoderm develops into muscles, bones, blood vessels, and other connective tissues. Microderm is not a recognized germ layer in embryonic development.