Changes that have occurred in living organisms over the past four billion years are due primarily to
A. extinction of species.
B. continental drift.
C. changes in geological periods.
D. interaction of genetic and environmental changes.
E. the change in the orbit of the moon, causing mass extinction due to volcanic activity.
D. interaction of genetic and environmental changes.
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Imagine that horn color in Hodags (folkloric creatures of Wisconsin) is controlled by a single gene so that when you mate a Hodag homozygous for bright orange horns (COCO) with a Hodag homozygous for ivory horns (CICI), numerous offspring are produced, all with pale orange horns. Now consider that you cross an orange-horned Hodag with an ivory-horned Hodag and get an F1.
A. 9 bright orange: 6 pale orange: 1 ivory B. 1 bright orange: 2 pale orange: 1 ivory C. 3 bright orange: 1 ivory D. 1COCO: 2COCI: 1CICI E. 3COCO: 1CICI Clarify Question
What best summarizes the oocyte's contribution to the zygote? a. The oocyte contributes paternal DNA
b. Numerous substances are contributed by the oocyte, including maternal DNA, enzymes, yolk, and proteins. c. Nothing; an oocyte forms after several cleavages of the zygote. d. Oocytes are the source of the enzymes used by the sperm to penetrate the egg's membrane.
All of the following are gymnosperms EXCEPT
A. Pines. B. Ginkgo. C. Cycads. D. Horsetails.
The raw materials of science are:
A) hunches. B) theories. C) predictions. D) observations. E) hypotheses.