Cheetahs were almost extinct but conservation efforts managed to save them. Now, most cheetahs are genetically identical. What phenomenon explains this?
A. Gene flow
B. Bottleneck effect
C. Natural selection
D. Selective mating
Ans: B. Bottleneck effect
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Bacterial infections have become much more of a threat to human health due to
A. the increased use of antibiotics. B. an increase in acquired antibiotic resistance by innocuous strains. C. horizontal transfer of pathogenicity. D. both an increased use of antibiotics and an increase in acquired antibiotic resistance by innocuous strains. E. All of the events given have increased the threat of bacterial infections.
A likely biological basis of major depressive disorder is
A) reuptake pumps for serotonin in the presynaptic neuron membrane that are overactive, depleting serotonin in the synapse. B) absent reuptake pumps for serotonin in the presynaptic neuron membrane. C) reuptake pumps for serotonin in the postsynaptic neuron membrane that do not function adequately. D) reuptake pumps for serotonin in the postsynaptic neuron membrane that are overactive, depleting serotonin in the synapse.
You have a significant reduction in the amount of pulmonary surfactant. What is the likely effect?
a. The risk of bacterial infection will increase. b. The risk of having chronic obstructive pulmonary disease will increase. c. The bronchioles will constrict, which will increase airway resistance. d. The lungs will be difficult to inflate. e. Gas exchange cannot occur.
Genetic exchange between 2 homologous chromosomes is called
A. pleiotropy. B. crossing over. C. synapsis. D. independent assortment. E. allelic exchange.