The difference between an edge and an ecotone is that an edge is ________, whereas an ecotone is ________.

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#Question id: 6988

#Unit 5. Developmental Biology

Many cells in the body divide only rarely, if at all; neurons, red blood cells, and keratinocytes are extreme examples. In which portion of the cell cycle would such cells be considered to be?

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#Question id: 23839

#Unit 2. Cellular Organization

Which of the following myosin molecule have 2 heads, but does not assemble into filaments?

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#Question id: 2934

#Unit 2. Cellular Organization

Cyclin D/Cdk4 functions during:

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#Question id: 9276

#Unit 6. System Physiology – Plant

The carotenoid b-carotene, whose structure and absorption spectrum at,

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#Question id: 15150

#Unit 8. Inheritance Biology

In this problem we will explore some of the many ways that mutations in two different genes can interact to produce different Mendelian ratios. Consider a hypothetical insect species that has red eyes. Imagine mutations in two different unlinked genes that can, in certain combinations, block the formation of red eye pigment yielding mutants with white eyes. In principle, there are two different possible arrangements for two biochemical steps responsible for the formation of red eye pigment. The two genes might act in series such that a mutation in either gene would block the formation of red pigment. Alternatively, the two genes could act in parallel such that mutations in both genes would be required to block the formation of red pigment.

Further complexity arises from the possibility that mutations in either gene that lead to a block in enzymatic activity could be either dominant or recessive. If the crosses is made between a wild type insect with red eyes and a true breeding white eyed strain with mutations in both genes. Such considerations yield the Pathways in series with recessive mutations in both genes, the F1 progeny shows will have red eye, what is the expected phenotypic ratio of red to white eyed insects in the F2.