Describe the experimental evidence for the selective adhesion property of cells
What will be an ideal response?
ANSWER: Easily recognizable cells from the primary cell layers of amphibian embryos were placed
individually in alkaline solution, which caused the tissues to break down into single cells.
Researchers then combined different mixtures of cells, such as ectoderm + mesoderm and
ectoderm + mesoderm + endoderm. When the pH was returned to neutrality, the cells did
not remain segregated, but formed aggregates. In the ectoderm + mesoderm mixture, the
ectoderm moved to the periphery of the aggregate, surrounding the mesoderm cells. In the
ectoderm + mesoderm + endoderm mixture, the ectoderm cells were located on the
periphery, the endoderm cells were internal, and the mesoderm cells were between the
other two cell types. The researchers concluded that the cells had selective affinity for each
other; these properties result from cell surface molecules that give cells specific adhesion
properties.
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A. a total of 37 genes. B. genes for proteins used in oxidative phosphorylation. C. genes whose products are used in translation of mRNA. D. ribosomal genes. E. All of the items listed are correct.
The scientific approach that classifies organisms based on evolutionary relationships is known as ____
a. comparative morphology b. evolutionary ecology c. taxonomy d. cladistics e. genetics
In pines, the mature male gametophyte is called the ____
a. flagellated sperm b. pollen cone c. pollen tube d. pollen grain e. pollination drop
Cartilage is different from bone because cartilage:a
is rich in nerves. b. contains veins. c. has a matrix that is composed almost exclusively of collagen. d. contains lymphatic vessels. e. contains arteries.