Why do seals and sea lions retain zygapophyses in their backbones, while whales and sea cows do not?
How could we use this anatomy to determine the behavior of extinct whales (and what additional evidence do we have in one fossil whale to back up behavioral predictions)?
Seals and sea lions still come onto land from time to time, especially to give birth. Thus the presence of zygapophyses in extinct whales can be taken as an indication of occasional terrestrial behavior (probably to give birth). This prediction is supported by the fossilized protocetean whale Maiacetus: the animal is preserved with a late-term embryo inside of her but in the forward-facing position. This is like the condition in terrestrial mammals and unlike modern whales, which give birth underwater with the young born tail first.
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When myosin moves along the actin, it goes through cycles of binding and releasing (duty cycle). How does myosin keep from losing its place on the actin when it releases?
A) The time of the duty cycle is large (.99) so that it is only unattached a short time. B) The myosin is still attracted to the actin by weak electrostatic forces that prevent it from moving too far away during release. C) The myosin is attached to the actin by another protein that it uses as a safety line to prevent it from slipping too far back. D) The myosin is arranged in dimers so that when one releases, the other is bound.
In hyperopia, the eyeball is too short and the focal point is in front of the retina
Indicate whether the statement is true or false
The adrenal ______ secretes a small amount of both sex hormones.
A) medulla B) cortex C) accessory gland
The change in size of the bone marrow (where blood cells are produced) as an infant matures is an example of ________, whereas the transformation of blood stem cells into white blood cells is an example of ________.
A. development; differentiation B. growth; differentiation C. growth; development D. differentiation; growth E. differentiation; development