Scientists are always thinking about ways to
improve experimental design. In the text's
potato chip experiment, which of these might
do so?
a. show a different movie
b. exclude teenagers as group members
c. collect uneaten chip remains and weigh
them for both groups
d. provide free drinks
e. use a smaller theater
C
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There are cases, particularly in fruit flies, in which a normal body part grows in the wrong spot. For instance, legs on the head growing instead of antennae, or a second set of wings behind the normal pair. What can explain this?
A. These are due to the reappearance of stem cells, which are totipotent. B. These are due to misregulation of hormones from environmental contamination with pesticides. C. These occur as a result of mutations in homeotic genes, which normally act to direct development along the anterior-posterior axis. D. These naturally occur sometimes in animals that have metamorphic development, due to different organization of homeotic gene expression in larvae versus adults.
Which of the following does not occur during PCR?
A) Denaturation at high temperatures B) Synthesis of oligonucleotide primers C) Annealing of oligonucleotide primers D) Extension of primers by DNA polymerase E) Changes in the reaction temperature by a thermocycler
Toxoplasmosis includes all the following, except
A. ingesting pseudocysts from contaminated raw or undercooked meat. B. intrauterine infectious are generally mild with very little damage to fetal tissues. C. tachyzoites can cross the placenta. D. immunocompromised patients often develop a fatal, disseminated infection. E. ingesting or inhaling oocysts from infected cats or cat feces.
what does clonal de-selection (deletion) do?
What will be an ideal response?