Plant responses to the relative lengths of light and dark periods in their environment during each 24-

hour period are



a. gravitropisms.
b. photoperiodisms.
c. thigmotropisms.
d. circadian rhythms.
e. phototropisms.


B

Biology & Microbiology

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Chapter 22 - Genes and Disease - Cancer Copyright Cengage Learning. Powered by Cognero. Page 4 a. proto-oncogene b. pre-oncogene c. post-oncogene d. dys-oncogene e. oncogene

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In a dihybrid cross exhibiting complete genetic linkage, what would you expect?

A) one parental allele combination occurring more frequently than another B) two equally frequent gametes containing only parental allele combinations C) only recombinant gametes D) one parental allele combination occurring more frequently than another and no recombinant gametes E) two equally frequent gametes containing only parental allele combinations and no recombinant gametes

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Exotoxins, produced by Gram-negative bacteria, are highly antigenic and can be inactivated to form toxoids and used as vaccines.

a. true b. false

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What stimulates germination of desert plant seeds after a hard rain?

A) production of auxins B) removal of abscisic acid C) cooler temperatures D) activation of cytokinins

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