Three Models for Contractile-Ring Positioning in Animal Cells Are Presented

question 54

Short Answer

Three models for contractile-ring positioning in animal cells are presented in the schematic diagrams below. Answer the following question(s) according to these models.

-In classic experiments carried out in the 1960s and schematized below, an egg of the sand dollar Echinarachnius parma was made into a torus shape using a glass bead on the end of a needle, to study the influence of microtubules on cleavage-furrow positioning. The cells were allowed to undergo two rounds of mitosis. After the second mitosis, an extra furrow (indicated by a red arrowhead) was observed between the two asters that did not have a spindle between them. Which of the models (1 to 3) is more consistent with this observation? Write down 1, 2, or 3 as your answer.

Analyze the enforceability of agreements based on past consideration or moral obligations.

Distinguish between illusory promises and conditional promises in the context of contract enforceability.

Evaluate the legal validity of exclusive dealing contracts and requirements contracts.

Recognize contracts that are binding without consideration, including their exceptions under specific circumstances.