Consider the following points: (a) All excavates live in environments where oxygen availability is low; (b) all excavates lack mitochondria;
and (c) all excavates have some mitochondrial genes. Based on this information, which of the following statements is true of the excavate lineage?
A) Their ancestors were eukaryotes that existed prior to the origin of mitochondria.
B) Their ancestors had mitochondria, but the mitochondria were lost over time.
C) Their ancestors were not able to metabolize glucose.
D) Excavates are in the process of acquiring mitochondria through evolutionary adaptation.
Answer: B
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In the formula, dN/dt = rN(K-N)/K, the rate of population growth approaches zero as
A. carrying capacity approaches zero. B. the age-specific fertility rate approaches zero. C. the per capita growth rate declines. D. the population size approaches the carrying capacity. E. carrying capacity declines with increasing population size.
In the horses example above, if a homozygous black trotter is crossed to a chestnut pacer,
(a) what will be the appearance of the F1 and F2 generations? (b) which phenotype will be the most common? (c) which genotype will be the most common? (d) which of the potential offspring will be certain to breed true? What will be an ideal response?
Visual accommodation involves the ability to ____.
A. change the sensitivity of the rods and cones by means of neurotransmitters B. change the position of the retina C. change the thickness of the lens by contracting or relaxing certain muscles D. protect the eyeball from foreign matter E. prevent eye strain
In green plants, most of the ATP for synthesis of proteins, cytoplasmic streaming, and other cellular activities comes directly from
a. photosystem I b. photosystem II c. the Calvin cycle d. oxidative phosphorylation e. photophosphorylation