Which of the following illustrates the free-rider problem?
a. By reliably reciprocating a cooperative behavior, all individuals in the population increase their fitness.
b. Some daughters forego having offspring of their own as they help their mother with brood care.
c. An individual spends only half an hour grooming others for each hour of grooming it has re-ceived.
d. Some individuals forgo reproduction to avoid overpopulation of a species' habitat.
C
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Which of the following statements best describes the effect of climate on biome distribution?
A) Average annual temperature and precipitation are sufficient to predict which biome will be found in an area. B) Seasonal fluctuation of temperature is not a limiting factor in biome distribution if areas have the same annual temperature and precipitation means. C) The average climate and pattern of climate are important in determining biome distribution. D) Temperate forests and grasslands are different biomes because they receive a different quality and quantity of sunlight, even though they have essentially the same annual temperature and precipitation. E) Correlation of climate with biome distribution is sufficient to determine the cause of biome patterns.
An electron microscope must use electromagnet 'lenses'shaped like donuts to direct the electrons onto the specimen. Why aren't they solid, like the lenses in a light microscope?
A. A magnetic field cannot be applied across a completely solid object-there must be an opening within the object for the field to be applied through. B. The user has to be able to physically look through the magnets to focus the beam of electrons onto the specimen, since the metal of the magnets is opaque. Without a hole in the middle, the user wouldn't be able to see! C. The electrons would destroy the electromagnet material unless there was a physical hole for them to travel through on their way to the specimen. D. Electrons are particles, and particles cannot travel through a solid item. The hole in the middle allows them to travel from the source of the electrons to the specimen.
Studies of the Pax6 gene and its homologs suggest that
A. the eye has evolved independently multiple times. B. the eyes of many different species are descended from a common ancestor. C. the master genes of the eye in various species are not homologous. D. the simple eyes of invertebrates and complex eyes of vertebrates arose from two different ancestral control genes.
The human axial skeleton includes
_____ the sternum. _____ the vertebral column. _____ the humerus and tibia. _____ the femur. _____ the pelvis.