4. (2 pts.) We see 3 different developmental strategies in mammals: monotremes (

Question

4. (2 pts.) We see 3 different developmental strategies in mammals: monotremes (lay shelled eggs), marsupials (part internal and part external development), and placentals (fully internal development). Each type of development has its advantages and drawbacks. For any ONE of these (your choice), state one benefit and one drawback. 5. (1 pt.) Why do animals like cnidarians, particularly corals and anemones, undergo metamorphosis, in other words, why is metamorphosis a successful strate gy for them? 6. 1 pt) For animals that undergo metamorphosis, what is one risk they could potentially face? 7. (1 pt) The germ layer that distinguishes triploblasts from diploblasts is the: ENDODERM MESODERM/ECTODERM (circle one). What is one structure that is derived from this tissue layer? 8. (1 pt.) Sea urchins are: PROTOSTOMES/DEUTEROSTOMES (circle one), which means they have cell cleavage, cell fate and coelom

Explanation / Answer

Monotremes are the mammals that lay eggs. Monotremes have only single duct for their urinary and reproductory system. They have single cloaca where as most of the other mammals have separate genital tract.They are nonplacental mammals. Monotremes undergo meroblastic cell division. This means that cells at the yolk’s edge have cytoplasm continuous with that of the egg, which allows the yolk and embryo to exchange waste and nutrients with the surroundings.

Cnidarians are are the aquatic animals which have specialized cells for capturing their prey. They undergo metamorphosis a process by which the animal undergoes changes after giving birth.they have a change in their nutrition sources and behavioral changes. This change has become necessary in them for their survival which becomes the part of evolution.

After the metamorphosis there would be rapid change in their body which could make them difficult for their survival as their physical and chemical changes in their body needs a new environment but still time could give them a chnace to adjust depending upon the surroundings doing the best for survival.

Mesoderm is the layer that differentiates from diplobasts and triptoblasts. Mesoderm is the germ layer formed from inward movement of some cells during gastrulation. The formation of mesoderm leads to the development of coelom. Organs in the coelom can move freely grow and develop independently of the cell wall while the fluids in them protects them from shocks.

Sea urchins are Deuterostomes, which means they have Intermediate cell cleavage, developmental cell fate and enterocoely coelom.

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