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At the embryonic node, two populations of cilia work together to establish left-right asymmetry. Which of the following correctly describes the roles of each type?

Match each description on the left to the correct type of neurulation on the right.  A flat sheet of epithelial cells undergoes apical constriction at hinge points and folds into a hollow tube. –> [a] Mesenchymal cells condense into a solid rod, then a lumen forms at its center –> [b] Occurs more anteriorly in vertebrates; responsible for brain formation –> [c] Occurs more posteriorly in vertebrates (A defect in this process is more likely responsible for spina bifida in humans ) –> [d]

A scientist wants to test the hypothesis that children born to mothers who smoked during pregnancy have a higher incidence of craniofacial abnormalities. She identifies 500 children with craniofacial abnormalities and 500 children without, then surveys their mothers about smoking habits during pregnancy. Which of the following correctly describes this study and its limitations?

Which of the following correctly describes the location of the Izumo and Juno proteins during sperm-egg fusion?

A patient is diagnosed with a neurocristopathy. Which of the following observations would be consistent with this diagnosis? Select all that apply.

Read the following passage and see the figure below. This is question 2 of 2 about this passage and figure. “The popular herbicide atrazine induces a compound that converts testosterone into estrogen. Researchers wanted to know whether the survival of some amphibian species could be at risk due to atrazine’s effects on the number, function, and fertility of males. In Hayes et al. (2002), researchers tested the hypothesis that atrazine reduces testosterone levels in male frogs by exposing one group of 90 male frogs to 25 parts per billion (ppb) atrazine every 3 days for 46 days. A group of 90 control males and a group of 90 control females were treated identically to the atrazine-treated group, except they were not exposed to atrazine. All frogs were housed individually and fed Purina rabbit chow. After 46 days, individual testosterone levels were measured in frogs from each group. The results are below.”   QUESTION: Identify the researchers’ hypothesis and prediction.

Two migrating NCCs are traveling through the embryo and make contact with each other. According to the principle of contact inhibition of locomotion, what will happen next?

Read the following passage and see the figure below. This is question 1 of 2 about this passage and figure. “The popular herbicide atrazine induces a compound that converts testosterone into estrogen. Researchers wanted to know whether the survival of some amphibian species could be at risk due to atrazine’s effects on the number, function, and fertility of males. In Hayes et al. (2002), researchers tested the hypothesis that atrazine reduces testosterone levels in male frogs by exposing one group of 90 male frogs to 25 parts per billion (ppb) atrazine every 3 days for 46 days. A group of 90 control males and a group of 90 control females were treated identically to the atrazine-treated group, except they were not exposed to atrazine. All frogs were housed individually and fed Purina rabbit chow. After 46 days, individual testosterone levels were measured in frogs from each group. The results are below.”   QUESTION: What is a controlled variable in this experiment?

74. Which of the following routes of administration will be injected into the muscle?

62. Healing time for muscles and tendons is longer than the time for ligament reconstructions. Muscles & tendons also heal weaker than ligaments.