Biol 367 Exam 2 Test Questions And All
Correct Answers.
What are the 3 life stages of xenopus? - Answer 1. Embryonic Stage
2. Larval Stage
3. Adult Stage
What happens during adult stage? - Answer Either sperm or egg are developed (gametogenesis)
What happens during embryonic stage? - Answer Cleavage, Gastrulation, organogenesis
What happens during larval stage? - Answer Metamorphosis
What happens during oogenesis? (7 steps) - Answer 1. primordial germ cell migrates to gonad
2. Stem cell then undergoes mitosis 10,000 times
3. Primary oogonium then undergoes mitosis 4 more times
4. Nest of 16 oocytes undergoes meiosis
5. Growth with lampbrush chromosomes occurs
6. Follicle cells surround oocyte
7. Full grown oocyte
What are the two features of oocytes? - Answer Polarity (animal pole and vegetal pole) and Radial
symmetry (no left or right)
Describe how the grey crescent comes to be - Answer 1. A sperm fertilizes an egg and donates its
genetic material and centrioles
2. The sperm and egg's pronuclei fuse, which turn 2 1N cells into one diploid cell
3. The MTOC start polymerizing monomer tubules
4. The monomer tubules push outwards to form a new layer called the cortical cytoplasm
, 5. the microtubules then angle away from the sperm point of entry by 30º.
6. Microtubules depolymerize, the AP leaves a grey crescent which establishes the D/V axis and is the
site of gastrulation.
What happens when the embryo is exposed to UV light? - Answer Inhibits cortical rotation and causes
a featureless embryo
What happens when the microtubules are stabilized with D2O - Answer Dorsalized embryo
What happens when you impose secondary rotation with centrifugation? - Answer Conjoined twins
What happens if you transplant the vegetal pole from an early embryo to an external environment? -
Answer No recognizable structure
Transplanting the VP to the AP of an early embryo causes __________ formation - Answer epidermis
Transplanting the VP of a late blastula to an external environment causes ________ formation - Answer
gut cell
Transplanting the VP of a late blastula to the AP causes ___________ formation - Answer epidermis
When are cells specialized? - Answer After mid blastula formation
Totipotent cells can form - Answer both whole embryo and placenta
Pluripotent cells can form - Answer many things but not placenta
multipotent cells can form - Answer limited sets of things and not the placenta
unipotent cells can form - Answer one thing
Correct Answers.
What are the 3 life stages of xenopus? - Answer 1. Embryonic Stage
2. Larval Stage
3. Adult Stage
What happens during adult stage? - Answer Either sperm or egg are developed (gametogenesis)
What happens during embryonic stage? - Answer Cleavage, Gastrulation, organogenesis
What happens during larval stage? - Answer Metamorphosis
What happens during oogenesis? (7 steps) - Answer 1. primordial germ cell migrates to gonad
2. Stem cell then undergoes mitosis 10,000 times
3. Primary oogonium then undergoes mitosis 4 more times
4. Nest of 16 oocytes undergoes meiosis
5. Growth with lampbrush chromosomes occurs
6. Follicle cells surround oocyte
7. Full grown oocyte
What are the two features of oocytes? - Answer Polarity (animal pole and vegetal pole) and Radial
symmetry (no left or right)
Describe how the grey crescent comes to be - Answer 1. A sperm fertilizes an egg and donates its
genetic material and centrioles
2. The sperm and egg's pronuclei fuse, which turn 2 1N cells into one diploid cell
3. The MTOC start polymerizing monomer tubules
4. The monomer tubules push outwards to form a new layer called the cortical cytoplasm
, 5. the microtubules then angle away from the sperm point of entry by 30º.
6. Microtubules depolymerize, the AP leaves a grey crescent which establishes the D/V axis and is the
site of gastrulation.
What happens when the embryo is exposed to UV light? - Answer Inhibits cortical rotation and causes
a featureless embryo
What happens when the microtubules are stabilized with D2O - Answer Dorsalized embryo
What happens when you impose secondary rotation with centrifugation? - Answer Conjoined twins
What happens if you transplant the vegetal pole from an early embryo to an external environment? -
Answer No recognizable structure
Transplanting the VP to the AP of an early embryo causes __________ formation - Answer epidermis
Transplanting the VP of a late blastula to an external environment causes ________ formation - Answer
gut cell
Transplanting the VP of a late blastula to the AP causes ___________ formation - Answer epidermis
When are cells specialized? - Answer After mid blastula formation
Totipotent cells can form - Answer both whole embryo and placenta
Pluripotent cells can form - Answer many things but not placenta
multipotent cells can form - Answer limited sets of things and not the placenta
unipotent cells can form - Answer one thing
