Adhesion of plant cells is mediated by a pectin-rich region of the cell wall called the
a. external lamina.
b. middle lamella.
c. intermediate lamella.
d. plasmodesmata.
Ans: b. middle lamella.
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GGG and GGC are codons for the amino acid, glycine. A mutation caused the insertion of a cytosine in place of the guanine during DNA replication. Over many generations the DNA changes so that the frequency of GGC is similar to that of GGG. What is this phenomenon called?
A. directional selection
B. bottleneck effect
C. stabilizing selection
D. adaptive variation
E. neutral variation
The birds are:
a. stenotherms. b. eurytherms. c. homeotherms. d. poikilotherms. e. ectotherms.
What describes the greater fitness of individuals who carry one copy of the sickle-cell allele in areas where malaria is common?
A) low genetic variability B) heterozygote advantage C) the benefit of mutualism D) competitive exclusion
Given that nonexperimental datasets are likely to have treatments that have not been randomly assigned, what is likely to contribute to difference in average outcomes between groups with different treatment levels?
A. Some of those differences are driven by a selection bias B. Heteroskedasticity C. Skewed perceptions of quality D. Non-normality of the underlying population distribution