Which statement best describes how flight and feathers are related in the evolution of birds?
A) The first flying birds did not have feathers, which evolved later.
B) Feathers and flight evolved at the same time.
C) The first feathered ancestors to birds did not fly but may have used their feathers for insulation and display.
D) Feathers are soft and do not leave fossils or fossil traces, so it is unknown which organisms first had feathers.
Answer: C
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You have a planar bilayer with equal amounts of saturated and unsaturated phospholipids. After testing the permeability of this membrane to glucose, you increase the proportion of unsaturated phospholipids in the bilayer
What will happen to the membrane's permeability to glucose? A) Permeability to glucose will increase. B) Permeability to glucose will decrease. C) Permeability to glucose will stay the same. D) You cannot predict the outcome. You simply have to make the measurement.
In which of the following situations is genetic drift likely to occur?
A. A small population of lizards is isolated on a small island. B. A mouse develops a fur coat that enables it to hide more readily from predators. C. Two schools of tuna merge together to form one large population. D. A river changes course, changing the local environment for a population of butterflies.
Which of the following statements is true?
a. When lipids and water are mixed, it is the water molecules that isolate themselves into droplets. b. When lipids and water are mixed, the lipids dissolve and enter into a solution. c. Lipids are nonpolar and will not dissolve in water. d. Polar substances are able to pass through a plasma membrane more readily than nonpolar substances. e. All portions of a phospholipid molecule found in a membrane are classified as nonpolar.
Which of these would be considered a cis-regulatory element for a gene?
A. Methylation of DNA preventing transcription B. A region of DNA sequence upstream of a gene where transcription factors bind C. A DNA binding protein that functions to repress transcription D. A protein that binds to an enhancer to activate gene expression E. a ribosome that translates a mRNA sequence to produce a transcription factor