Which of the following excretory structures is used by birds?
A. nephridia
B. cloaca
C. urethra
D. flame cells
Answer: B
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A microbiologist is working with two genera of bacteria, A and B, to determine if cells are competent. Strains are grown under optimal conditions, and DNA fragments that carry the gene for green fluorescent protein is added to each culture at 20-minute intervals. Samples from each treatment are plated to nutrient agar and incubated, after which the plates are examined under an ultraviolet lamp. The microbiologist observes that all plates of bacteria B contain colonies that are fluorescent, while for bacteria A only the plates from stationary phase demonstrate fluorescent colonies. What can be concluded from these results?
A. Competence in bacteria A is constitutively expressed. B. Competence in bacteria B is dependent on the phase of growth. C. Both bacteria A and bacteria B cells are competent. D. Neither bacteria A nor bacteria B cells are competent.
Ecologists develop a(n) ________ life table to follow the fate of a group of individuals, who were all born at a given time, from birth to death
Fill in the blank(s) with correct word
Before fats can be metabolized in aerobic cellular respiration they must be converted to
A. simple sugars. B. fatty acids and glycerol. C. amino acids. D. fatty acids and amino acids.
Which statement about analogies is correct?
a. They occur only as errors. b. They are synonymous with homologous traits. c. They are derived by similar environmental constraints. d. They are a form of mutation.