AP Bio - Unit 8 on Ecology Practice Test

(46) Which of the following best approximates the ratio of males to females among individuals below fifteen years of age? Country I Country II (A) 1 : 1 1 : 1 (B) 0.75 : 1 0.75 : 1 (C) 0.5 : 1 0.5 : 1 (D) 1 : 1 0.5 : 1 (E) 0.75 : 1 1 : 1

(A) 1 : 1 1 : 1

(8) A study of the metabolic rate in a terrestrial community shows that the energy released by respiration exceeds the energy captured in photosynthesis. Which of the following situations is occurring? (A) Community biomass is decreasing. (B) Community biomass is increasing. (C) A climax community has been reached. (D) The first law of thermodynamics is not in effect. (E) The second law of thermodynamics is not in effect.

(A) Community biomass is decreasing.

(54) Species that feed at only one trophic level include which of the following? I. Zooplankton II. Planktivorous fish III. Killer whales (A) I only (B) II only (C) III only (D) II and III only (E) I, II, and II

(A) I only

(22) Which of the following is the most direct result of the heating up of pond water during the summer? (A) The water's ability to hold oxygen decreases. (B) The water's ability to act as a buffer changes. (C) The viscosity of the water increases. (D) Hydrogen bonding at the surface of the water increases. (E) Less light penetrates the surface of the water.

(A) The water's ability to hold oxygen decreases.

(2) If the larvae of a particular species of mosquito are to survive to the adult stage, the eggs must be laid in the trapped pool of water of the northern pitcher plant. The mosquito larvae provide no apparent benefit or harm to the pitcher plant. This type of interaction is an example of (A) commensalism (B) predation (C) parasitism (D) mutualism (E) competition.

(A) commensalism

(41) The organic and inorganic materials in all of the organisms in the diagram will eventually return to the environment by the action of (A) decomposers (B) producers (C) primary consumers (D) secondary consumers (E) top carnivores

(A) decomposers

(20) Which of the following is characteristic of a fast—moving stream ecosystem? (A) high levels of dissolved oxygen (B) high salinity (C) large numbers of anaerobes (D) eutrophication (E) thermal stratification

(A) high levels of dissolved oxygen

(29) Which of the following is a symbiotic relationship that was probably present in the first terrestrial plants and is still important for the mineral nutrition of present—day angiosperms? (A) mycorrhizae (B) lichens (C) insects pollinating flowers (D) carnivorous plants feeding on insects (E) epiphytes growing on a tree truck

(A) mycorrhizae

(9) Eutrophication in lakes is frequently the direct result of (A) nutrient enrichment (B) industrial poisons (C) a diminished supply of nitrates (D) an increase in predators (E) decreased light penetration

(A) nutrient enrichment

Level Population 4 4 3 360 2 780 1 5,782 (27) In a simple ecosystem, a census of the populations in four successive trophic levels was taken as shown above. If level 1 is composed of photosynthetic autotrophs, then the trophic level with 780 individuals will most likely represent? (A) primary consumers (B) secondary consumers (C) tertiary consumers (D) decomposers (E) producers

(A) primary consumers

(12) All of the following are density—dependent factors that limit animal populations EXCEPT (A) weather (B) predation (C) birthrate (D) food competition (E) mortality

(A) weather

(57) After 10 days, the distilled water culture dish has approximately how many duckweed plants? (A) 3 (B) 6 (C) 9 (D) 12 (E) 15

(B) 6

(24) Which of the following best explains why many different species can live together within an ecosystem with limited resources? (A) Each species lives in a slightly different habitat. (B) Each species occupies a different niche. (C) Each species inhabits a different biome. (D) Each species makes up a different population. (E) Each species functions at a different trophic level.

(B) Each species occupies a different niche.

(25) Fire has which of the following effects on a community? (A) It causes all of the plants and animals in the community to become dormant. (B) It recycles dead plant material, thus nutrients become available. (C) It prevents reestablishment of the prefire community. (D) It allows for increased mutation rates in the surviving species. (E) It forces predators to become omnivores.

(B) It recycles dead plant material, thus nutrients become available.

(40) All of the following statements about the diagram are correct EXCEPT (A) The grasshopper is an herbivore. (B) Only two trophic levels are depicted. (C) The mouse and grasshopper are at the same trophic level. (D) The grass is a producer. (E) All of the organisms except grass are consumers, regardless of position.

(B) Only two trophic levels are depicted.

(19) All of the following statements about the pyramid of biomass are correct EXCEPT (A) Biomass is the total dry mass of the organisms present. (B) The base of the pyramid generally represents primary consumers. (C) The amount of biomass at a particular level of the pyramid depends on the amount of energy available. (D) Certain toxins tend to become concentrated at upper levels of the pyramid. (E) Biomass pyramids tend to vary for different ecosystems.

(B) The base of the pyramid generally represents primary consumers.

(10) Warning coloration is most effective against vertebrate predators that are (A) color—blind (B) able to learn through trial and error (C) highly dependent on olfactory sensation (D) camouflaged (E) nocturnal hunters

(B) able to learn through trial and error

(14) In the nitrogen cycle, the transformation of gaseous nitrogen into nitrogen—containing compounds is performed primarily by (A) fungi (B) bacteria (C) green plants (D) herbivores (E) carnivores

(B) bacteria

(47) If, in Country I, infant mortality declined and the birth rate remained the same, then initially the population would be expected to (A) be more evenly distributed among the age classes (B) be even more concentrated in the young age classes (C) stabilize at the illustrated level for all age classes (D) increase in the oldest age classes (E) increase in the median age classes

(B) be even more concentrated in the young age classes

(11) Competition for food would probably be most severe between two (A) closely related species in different niches (B) closely related species in similar niches (C) unrelated species in different communities (D) unrelated species in the same community occupying different niches (E) ecological equivalents in different niches

(B) closely related species in similar niches

(1) Competitive exclusion is most likely to occur between two (A) closely related species occupying different niches (B) closely related species occupying the same niche (C) related species occupying different habitats (D) unrelated species occupying different niches (E) populations of the same species

(B) closely related species occupying the same niche

(49) The type of population growth represented by that portion of the graph line enclosed in the bracket is most accurately termed (A) stable (B) exponential (C) density-dependent (D) arithmetic (E) decelerating

(B) exponential

(28) The population of the country shown in the figure above will most likely (A) stabilize within 20 years (B) increase for many years (C) not change (D) reach zero population growth within 10 years (E) decrease within 20 years

(B) increase for many years

(5) A species of malaria carrying mosquito lives in a forest in which two species of monkeys, A and B, coexist. Species A is immune to malaria but species B is not. The malaria—carrying mosquito is the chief food for a particular kind of bird in the forest. If all of these birds are eliminated suddenly by hunters, which of the following would be the immediate observable consequence? (A) increased mortality in monkey species A (B) increased mortality in monkey species B (C) increased mortality in the malaria—carrying mosquitoes (D) emergence of malaria—resistant strains in monkey species B (E) emergence of malaria—sensitive strains in monkey species A

(B) increased mortality in monkey species B

(56) In similar rocky coastal ecosystems where sea otters have disappeared due to human harvesting or killer whale predation, the kelp forests also disappear and the species diversity of the community decreases drastically. In these ecosystems, the sea otter can best be described as (A) top carnivore (B) keystone species (C) primary producer (D) secondary herbivore (E) dominant species

(B) keystone species

(58) In pond water, the duckweed population grows at an average rate of (A) 1 plant per day (B) 2 plants per day (C) 1 plant per 3 days (D) 3 plants per day (E) 9 plants per 15 days

(C) 1 plant per 3 days

(53) The minimum number of trophic levels in a food chain ending with killer whales is (A) 2 (B) 3 (C) 4 (D) 5 (E) 6

(C) 4

(60) Under which of the following additional conditions would the duckweed population be most likely to grow faster? (A) Oxygen gas bubbled through the culture dishes (B) The addition of an organism that eats duckweed (C) The addition of distilled water to every culture dish (D) An increase in light intensity (E) The addition of glucose to the culture medium

(C) The addition of distilled water to every culture dish

(30) In the process of succession, which of the following is true of K—selected plant species? (A) They keep their carrying capacity at a minimum level. (B) They usually reproduce early in life. (C) They are usually found in climax stages of succession. (D) They are the dominant species in early stages of succession. (E) They have a short lifespan.

(C) They are usually found in climax stages of succession.

(48) Over the next 10—15 years, the stabilization of Country I's population at its current size would require that (A) infant mortality be reduced to about half the present level (B) the death rate be reduced drastically (C) each couple produce fewer children than the number required to replace themselves (D) about 15 years be added to the life expectancy of each person (E) couples have an average of only 3 children

(C) each couple produce fewer children than the number required to replace themselves

(4) Species that utilize the same source of nutrition within a food web can best be described as (A) providing double links in a food chain (B) being homeothermic relative to energy flow (C) occupying the same trophic level (D) being secondary consumers within a complex food web (E) being autotrophs, heterotrophs, or omnivores

(C) occupying the same trophic level

(15) During the carbon cycle, which of the following carbon compounds would be utilized as an energy source by heterotrophs? (A) calcium carbonate (B) carbonic acid (C) organic molecules (D) carbon dioxide (E) carbon monoxide

(C) organic molecules

(63) The population density at point Q indicates that (A) exponential population growth is occurring (B) predation is beginning to occur (C) the reproductive rate equals the death rate (D) the average age of individuals is decreasing (E) the reproductive capacity for each individual is increasing

(C) the reproductive rate equals the death rate

(13) Which of the following is true about secondary consumers in an ecosystem? (A) They eat only plants. (B) They are eaten by primary consumers (C) They are smaller and weaker than are primary consumers. (D) They are fewer in number than are primary consumers. (E) They contain the greatest total biomass in the system.

(D) They are fewer in number than are primary consumers.

(6) In traveling from a forest ecosystem to a grassland, one notes that the trees gradually give way to prairie grasses. The critical factor governing this shift is usually the (A) length of the growing season (B) annual mean temperature (C) availability of carbon dioxide (D) availability of water (E) availability of oxygen.

(D) availability of water

(51) The dashed line on the graph represents the (A) maximum population size (B) average birth rate (C) biotic potential of the population (D) carrying capacity of the environment (E) point of maximum effect for density—independent factors

(D) carrying capacity of the environment

(3) In the food pyramid above, which of the following organisms are herbivores? (A) humans (B) fish (C) minnows (D) copepods (E) algae

(D) copepods

(16) Which of the following best explains why there are seldom more than five trophic levels in a food chain? (A) Most carnivores function at more than one trophic level. (B) Trophic levels above this number contain too many individuals. (C) Top carnivores are too few in number to prey effectively (D) The ecosystem contains too much biomass. (E) Energy is lost from each trophic level.

(E) Energy is lost from each trophic level.

(64) The population would be most likely to remain at the level shown at Q under which of the following conditions? (A) All predators are eliminated. (B) The population size is well below its carrying capacity. (C) Euglena is a primary producer. (D) Euglena is a primary consumer. (E) Environmental conditions do not fluctuate.

(E) Environmental conditions do not fluctuate.

(62) In which region of the curve is population size most likely to exhibit regulation by availability of resources such as nutrients, nest sites, and places to hide from predators? (A) I only (B) II only (C) I and II (D) II and III (E) III and IV

(E) III and IV

(59) Duckweed vegetatively reproduced at the fastest rate in (A) pond water (B) nitrate—enriched distilled water (C) pond water with added chlorophyll (D) distilled water (E) N—P—K fertilizer solution

(E) N-P-K fertilizer solution

(18) Which of the following is an important characteristic of the tropical rain forest biome? (A) High light levels on the forest floor. (B) The dominance of a small number of tree species. (C) More widely fluctuating temperatures than in most other biomes. (D) Distinct rainy and dry seasons. (E) Rapid recycling of nutrients

(E) Rapid recycling of nutrients

(55) If a fat—soluble but poorly metabolized substance such as DDT gets into this ecosystem, the highest tissue concentrations will most likely occur in which of the following? (A) Phytoplankton (B) Zooplankton (C) Abalones (D) Sea otters (E) Seals

(E) Seals

(61) The dotted line marked K indicates which of the following? (A) The annual reproductive rate (B) The proportion of a population that can be removed without destroying its ability to maintain a stable population size (C) The carrying capacity of the population (D) The maximum number of offspring that each pair of parents can produce in a single year (E) The intrinsic rate of reproductive increase of the population

(E) The intrinsic rate of reproductive increase of the population

(23) The primary producers of the deep sea communities associated with hot water vents are (A) plants (B) tube worms (C) photosynthetic algae (D) cyanobacteria (E) chemoautrophic bacteria

(E) chemoautrophic bacteria

(26) A parasite may be described as an organism that derives nourishment from another living organism and (A) becomes necessary to the life of the host (B) is neutral in its effect on the host (C) benefits the host nutritionally (D) provides a supportive structure for the host (E) harms the host in the process

(E) harms the host in the process

(39) Which of the following organisms is most likely to be located at the apex of the pyramid of biomass? (A) grass (B) grasshopper (C) snake (D) mouse (E) hawk

(E) hawk

(17) An overlap in the niches of two species will most frequently result in (A) interspecific cooperation (B) a hybridization of species (C) a mutualistic symbiotic relationship (D) an increase in the biomass (E) interspecific competition

(E) interspecific competition

(50) The graph indicates that the sheep population most likely is (A) growing in excess of its carrying capacity, since fluctuations in population size occurred after 1850 (B) headed for extinction because of the population explosion about 1930 (C) regulated by density—dependent factors, because there appears to be about a 10—year cycle of sharp declines in size (D) shifting from K—selected strategy to an r—selected strategy (E) stable after 1850 under the effects of density—dependent regulating factors

(E) stable after 1850 under the effects of density—dependent regulating factors

(7) Grass → Cricket → Prairie chicken → Coyote → Vulture. In which organism in the food chain above would be the biological magnification of DDT concentration be most obvious? (A) grass (B) cricket (C) prairie chicken (D) coyote (E) vulture

(E) vulture