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Exam Development

Essay Instructions:

1. What is the difference between growth and development?
2. What is the difference between a zygote and an embryo?
3. What are the two hemispheres of the frog yolk and what is the role of each?
4. The typical frog has 7 developmental stages. List two of those stages and one important event that occurs each of those two stages.
5. Define and present an example of a embryonic homology
6. Define and present an example of a embryonic analogy
7. What is a teratogen? Provide one example
Module two
1. In a few sentences, explain von Leeuwenhoek’s hypothesis about the role of sperm in embryogenesis.
2. List and describe (1 -2 sentences) four ways the mammalian female reproductive tract influences sperm motility.
3. Three reasons why sea urchins are used as a model in fertilization studies.
4. Outline one model of how chemotaxis explains sperm attraction to the egg.
5. List 3 ways that polyspermy is prevented.
6. List and define (with 1-2 sentences) the five basic steps of recognition of sperm and egg.
Module Three
1. List 3 reasons why the zebrafish is an important model in early development studies.
2. How does amphibian cleavage and gastrulation differ from the zebrafish model?
3. In a few sentences explain the development of the mesoderm in an animals, avian, amphibian or fish model.
4. What is the primitive streak?
5. What is compaction?
6. Contrast the monozygotic and the dizygotic twin from fertilization to birth, including 3 distinct points of difference.
7. Of the three vertebrate classes we have considered, which has been the most difficult for scientists to study during the gastrulation phase? List three reasons.
8. Compare neural tube development in birds and fish.
List at least one characteristic unique to each and one common to each.
9. Compare neural tube development in mammals and amphibians. List at least one characteristic unique to each and one common to each.
10. Mammals have left-right axis development. List some distinctions between the left and right sides of a mammal 298
11. Define cleavage and rotational cleavage. 300
12. Unlike birds, fish , and amphibians, mammal embryos do not have a yolk. How do they compensate for the absence of a yolk? 305

Essay Sample Content Preview:

Exam Development
Author’s Name
University Affiliation
Exam Development
Part I
While growth refers to the change in size or physical development, development includes both the change in size, but also includes other factors of improvement.
A zygote is the first phase of prenatal development and it comprises of non-differentiated cells whereas an embryo is larger than the zygote. The zygote stage precedes the embryo stage.
Vegetal hemisphere and animal hemisphere are the two hemispheres of the frog’s yolk. The two hemispheres play different important roles. The vegetal hemisphere protects and nourishes the developing pole, whereas the animal hemisphere serves as the entry point of the sperm.
Two stages of from development are the cleavage and blastula formation. During the cleavage phase, the egg transforms from a single cell to an embryo. In the blastula formation, stage harbors the rapid cell division or rather mitosis.
Embryonic homology is the appearance of structures, which appear to have originated from a common ancestor. A typical example is the wing of a bird and the forelimb of a human.
Embryonic analogy is the appearance of structures, which perform similar functions. A typical example is the wing of a butterfly and the wing of a bird.
A teratogen refers to a substance or factors, which can interfere with the development of the embryo. In most cases, teratogens are found in the environment, and the mother may be exposed to them during pregnancy.
Part II
Leeuwenhoek held that sperms resembled seeds and that the female provided the nutrients, which could support the growth of the seeds. In this context, Leeuwenhoek is consistent with current literature on the same because there must be a fusion of the sperm and the egg to realize fertilization. Most importantly, the sperm cell facilitates fertilization.
Female reproductive
Production of seminal fluid that contains sugars and proteins, which support the survival of the sperms
The female reproductive tract has sperm storage sites that contain conditions, such as optimal temperatures, which enhance their survival.
Cervical mucus supports sperm motility
The fallopian tube contraction promotes sperm motility
Sea urchin models
The shape of their eggs and sperms resemble those of human beings
Fertilization success in sea urchins is very high
Sea urchins are tolerant to a variety of chemicals
A typical model of chematoxis is the sperm attraction to the follicular factors, which show an association with fertilization. The model suggests that after ovulation, the sperms meet the eggs at the fertilization sites within 24 hours. However, the majority of the sperms ejaculated in the female reproductive tract remain motionless in the storage sites until ovulation, when the sperm achieve maximum motility and move to the fertilization site. The manner in which they move remains a mystery, but the possible manner of movement is the attraction of the sperm to factors released by the eggs.
Prevention of polyspermy
Fast block, which is achievable through depolarization and dissolving of the egg
Slow block that occurs through removal of the egg’s sperm receptors, swelling of the vitelline membra...
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