All AP Biology Resources
Example Questions
Example Question #11 : Natural Selection
Which of the following is true regarding balancing selection?
It is the opposite of purifying selection
All of these
An example is heterozygote advantage
It maintains variation in a population
All of these
Balancing selection is a type of natural selection that maintains genetic variation in a population, making it the opposite of purifying selection. Examples of balancing selection include heterozygote selection, in which there is adaptive value for heterozygotes of an allele.
Example Question #12 : Natural Selection
During which of the following levels of biological organization can natural selection occur?
All of these
Gene
Individual
Group
All of these
Natural selection is defined as survival and reproduction based on a specific phenotype. Phenotypes that increase reproductive fitness are “selected for” on different levels. Natural selection can take place on different levels of biological organization including gene, individual, and group levels.
Example Question #13 : Natural Selection
Which of the following types of selection best describes the process in which fitness depends on phenotype frequency?
Sexual selection
Disruptive selection
Directional selection
Frequency-dependent selection
Frequency-dependent selection
Frequency-dependent selection is a type of natural selection in which the fitness of a phenotype depends on frequency. This includes positive frequency-dependent selection—fitness of a phenotype increases when it is common—and negative frequency-dependent selection—fitness of a phenotype decreases when it is common.
Example Question #1 : Understanding Biological Fitness
There are two very different reproductive strategies in nature: r-selection and k-selection. These strategies are so extreme, we typically observe organisms somewhere in between these two strategies.
Which of the following characteristics is not indicative of r-selection?
Small brood size
Very fast maturation of organisms
High brood mortality rate
Very little parental care
Small brood size
The r-selection strategy for reproduction is typically seen in environments that are very volatile and unpredicatable. It has a variety of characteristics including high brood sizes with a high mortality rate, and fast maturation with very little parental assistance. Low brood sizes are typically seen in the k-selection strategy for reproduction.
Example Question #2 : Understanding Biological Fitness
Which characteristic is least likely to affect an organism's biological fitness in the tundra?
Size
Exothermic versus endothermic regulation
Color
Nocturnal versus diurnal activity
Fur
Nocturnal versus diurnal activity
Biological fitness is directly related to the ability of an organism to survive and produce future progeny. There are a lot of factors that will play into an organism's fitness, especially in a harsh place like the tundra. Small size can be beneficial, as smaller animals require less food and can survive better in harsh environments, but large size can be beneficial to help preserve body heat. The color of an animal will help it to hide from predators; many tundra animals are white to help them blend in to the snow. Thermoregulation is extremely important in a cold environment; endotherms are able to regulate their own internal temperature, and will survive better than exotherms, which would be affected by the cold temperature of the air. Finally, fur and feathers help to trap body heat close to the skin and would enhance the fitness of animals in a cold environment.
Size, color, mode of thermoregulation, and fur all impact an animal's ability to survive in the tundra. Nocturnal activity, however, would not necessarily be favored over diurnal activity, as there is no clear advantage of one over the other in this specific environment.
Example Question #3 : Understanding Biological Fitness
In the evolutionary sense, which organism has the highest fitness?
A turtle that lays hundreds of eggs each nesting season, although an unusually small number of these eggs hatch successfully
A prairie dog that, though smaller than the average member of her species, has twice as many healthy young in each litter
A childless human male who lives to be over one hundred years old
A dog who cannot give birth due to a hip abnormality, but is healthy in all other respects
A sterile mule that can pull over 800 pounds
A prairie dog that, though smaller than the average member of her species, has twice as many healthy young in each litter
With regard to evolution and natural selection, fitness refers only to the ability of an organism to contribute to the next generation of its species. In other words, if an organism has a large number of viable offspring, its fitness is high, regardless of other factors like strength, size, and longevity.
Of these answer choices, the only organism with an above-average number of healthy, surviving offspring is the prairie dog. The mule and the dog have below-average fitness because they cannot give birth. The turtle also has below-average fitness because it produces an unusually low number of healthy offspring. The human male has average to below-average fitness; certain traits made him choose not to produce offspring, though he may have been able to produce numerous offspring.
Example Question #4 : Understanding Biological Fitness
Humans regulate their internal body temperature within a very narrow range. This is an example of __________.
constancy
metabolism
evolution
homeostasis
homeostasis
Homeostasis is the tendency of the body to maintain stable, constant states. Homeostasis is often mediated by negative feedback systems, which prevent the measure from getting too high or too low. Regulation of body temperature within a narrow range would be an example of homeostatic regulation. Other examples include blood glucose concentration and blood calcium concentration.
Metabolism refers to the chemical processes of the body. These processes can help maintain homeostasis, but are not directly responsible for body regulation.
Example Question #1 : Understanding Biological Fitness
Which of the following would be considered innate behavior?
Inflexible behavior
Decisions
Classical conditioning
Communicating
Courtship
Inflexible behavior
Innate behavior is known as inflexible behavior, in which learning plays no role in the behavior. Communicating, courtship, and decision making all rely on learned behavior from the environment.
Example Question #1 : Understanding Biological Fitness
Which organism would be considered the most biologically fit?
Lives 70 years and produces no offspring
Lives 36 years and produces 6 offspring
Lives 45 years and produces 3 offspring
Lives 27 years and produces 1 offspring
Lives 94 years and produces 5 offspring
Lives 36 years and produces 6 offspring
The most biologically fit organism is one that produces the most fertile offspring. Lifespan can correlate to the number of offspring produced, but is not a direct factor in determining fitness.
Since the organism that lives 36 years produced the most offspring (6), it is the most biologically fit.
Example Question #6 : Understanding Biological Fitness
In regard to the theory of evolution, “fitness” most likely refers to which of the following?
Reproductive success
All of these
Physical abilities of an individual
Flexibility of an individual
Reproductive success
In evolutionary terms, “fitness” refers to the reproductive success or reproductive potential of an organism—its contribution to its species' gene pool.
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