The ideal Christmas tree has a conical shape. The top of the tree is pointed and narrow, with clear apical dominance, and the bottom of the tree is wide, with extensive lateral branching
Certain evergreen species are suitable for use as Christmas trees because they have this shape normally and thus require little pruning or training as they grow. For example, spruces and firs are often grown as Christmas trees, whereas yews and longleaf pines are not.
Based on this information, spruces and firs are likely to have
A) high levels of auxins near the top and low levels of cytokinins at the bottom of the tree.
B) high levels of auxins near the top and high levels of cytokinins at the bottom of the tree.
C) low levels of auxins near the top and high levels of cytokinins at the bottom of the tree.
D) low levels of auxins near the top and low levels of cytokinins at the bottom of the tree.
B
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Albinism is a recessive disorder in which the skin and hair fail to produce pigment. The following question(s) ask you to evaluate the pedigree chart shown here in which "N" is the allele for normal pigmentation and "n" is the allele for albinism. The shaded circles for Deirdre and Shannon represent the only individuals expressing the disorder.
What is Bill's genotype?
A. NN B. nn C. Nn D. Cannot be determined
Reef-building corals do not typically reside at depths greater than 20 meters. Why?
a. The oxygen levels are too low to support. b. There is no available calcium carbonate to build their exoskeletons. c. There is insufficient light to support their dinoflagellate symbionts. d. There are no protists at those depths.
A eukaryotic chromosome consists of _____
a. DNA and lipids b. RNA and proteins c. DNA and proteins d. DNA and carbohydrates e. just DNA
The ____ consists of a whorl of petals
a. calyx b. sepal c. corolla d. carpel e. stamen