Section 26 College Board AP Biology Ecology

Which of the following statements most directly supports the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis?

a. during cold periods pond-dwelling animals can increase the number of unsaturated fatty acids in their cell membranes while some plants make antifreeze proteins to prevent ice crystal formation in tissues.

b. Bacteria lack introns while many eukaryotic genes contain many of these intervening sequences.

c. carnivores have more teeth that are specialized for ripping food while herbivores have more teeth that are specialized for grinding food.

d. Plants generally use starch molecules for storage while animals use glycogen and fats for storage.

d. Plants generally use starch molecules for storage while animals use glycogen and fats for storage.

A group of students designed an experiment to determine the effect of compost on the germination and growth of plants. The students set up experimental plots by mixing different ratios of soil and compost. They planted 20 pea and 20 melon seeds in each plot and watered each plot regularly. The students recorded the number of seeds that germinated, and as the plants grew, they recorded plant length, number and size of leaves, and general health observations.

The following observations were recorded.

• In all treatments, more pea seeds germinated than melon seeds.

• There was a week of rainy weather at three weeks.

• Melon plants developed fungal growth at four weeks.

• Melon plants grew longer than pea plants, but many melon leaves showed signs of yellowing as the weeks passed.

The students concluded that pea plants grew better in compost than did melon plants.

Which of the following best addresses the validity of the conclusion made by the students?

a. The conclusion is valid because the independent and dependent variables in the experiment were controlled.

b. The conclusion is valid because the experimental design included a large sample size.

c. The conclusion is invalid because other factors in the experiment (both abiotic and biotic) affected the results.

d. The conclusion is invalid because the units of measurement were not given in the experimental design.

c. The conclusion is invalid because other factors in the experiment (both abiotic and biotic) affected the results.

In the American Southwest, annually emerging cicadas are dependent upon the cottonwood trees in the floodplain. Adult male cicadas perch in the cottonwood trees and chirp to attract females. Females lay their eggs in the branches of the cottonwoods, and upon hatching, the cicada nymphs drop to the ground, burrow into the soil, feed on the tree roots, and later emerge as adults. Other organisms in the flood plain community prey on the cicadas.

Human activity has caused a decrease in the amount of flooding and an increase in the incidence of wildfires in the floodplain. In an investigation into the recent changes in the floodplain ecosystem, researchers monitored the soil temperature, amount of cottonwood ground coverage (area of the ground that is shaded by leaves), and cicada emergence for a period from mid June until late July.

To assess the impact of wildfires on soil temperature and cicada emergence, the researchers compared mean emergence dates for two natural sites where portions had been affected by wildfire. In addition, cicada emergence was monitored at an experimental site where the soil temperature was experimentally maintained.

The data from the temperature-controlled experimental plots can best be used to support which of the following conclusions about cicada development?

a. Adult cicadas lay more eggs when the soil is warmer than when the soil is cooler.

b. Adult cicadas mate more frequently when the soil is warmer than when the soil is cooler.

c. Cicada nymphs grow larger in warmer soil than in cooler soil.

d. Cicada nymphs mature to adults faster in warmer soil than in cooler soil.

Cicada nymphs mature to adults faster in warmer soil than in cooler soil.

The pesticide DDT was widely used in the 1940s as a method of insect control. In the late 1950s the first DDT resistant mosquitoes were discovered, and eventually DDT resistant mosquitoes were found globally. When DDT is used now, the development of DDT resistance in mosquito populations occurs in months rather than years.

Which of the following best explains the observations concerning DDT resistance in mosquitoes?

a. Competition for limited resources cause mosquitoes to migrate to geographical areas that have richer supplies of DDT.

b. The proportion of DDT resistant mosquitoes in a population remains constant due to the metabolic costs of DDT utilization.

c. Natural selection favors DDT resistant mosquitoes that are already present in a population where DDT exposure occurs.

d. DDT is a chemical signal that delays normal reproductive cycles in many mosquito populations.

c. Natural selection favors DDT resistant mosquitoes that are already present in a population where DDT exposure occurs.

A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after 7 days, and the opaque cover was permanently removed from Dish A. Both dishes were returned to the light and examined again at 14 days.

The most probable cause for the difference in mean stem length between plants in dish A and plants in dish B is which of the following?

a. shortening of cells in the stem in response to the lack of light

b. elongation of seedlings in responses to the lack of light

c. enhancement of stem elongation by light

d. genetic differences between the seeds

b. elongation of seedlings in response to the lack of light

To investigate the influence of predation risk on ray behavior, a student observed and counted the large marine animals swimming in a shallow, nearshore section of a coral reef ecosystem. The time of each observation was recorded relative to the time of high tide. The student noted that at low tide, when the water level is low, many of the large animals are forced out of the study area and into the deeper waters of the outer reef. During high tides, when the water level is high, the large animals are able to reenter the study area.

Over a three-day period, the student observed a total of 604 individual rays belonging to three species: cowtail rays, giant shovelnose rays, and black stingrays. For each ray that was sighted, its body length was estimated and its status as either alone (ungrouped) or found with other rays (grouped) was noted. Occasionally, rays were observed sifting through the sandy substrate of the study area to capture food items such as molluscs and crustaceans. In one instance, an injured ray with bite marks that were likely sustained in a shark attack was sighted. In addition to the rays, the student observed lemon sharks (n = 46) and blacktip reef sharks (n = 39).

Based on the results of the study, which of the following is the most likely connection between behavior and evolutionary fitness in a nearshore coral reef environment.

a. Rays that search for food alone at low tide typically grow to larger sizes than do rays that search for food in groups.

b. Rays that join groups during rising tides are always reproductively more successful than are rays that do not join groups.

c. Rays that swim far from shore at high tide often encounter a greater variety of species than do rays that remain near the shore.

d. Rays that roam across large distances during falling tides become stronger swimmers than do rays that spend more time at rest.

b. Rays that join groups during rising tides are always reproductively more successful than are rays that do not join groups