IB Biology SL C4.1 Populations and communities Question Bank

The grey partridge (Perdix perdix) is a species of bird that is found on farmland. Sparrowhawks (Accipiter nisus) and buzzards (Buteo buteo) are birds of prey that kill and feed on birds, including grey partridge. The number of grey partridges in a region of southern England was monitored from 1970 to 2004. The numbers of sparrowhawks and buzzards, seen from sampling positions during regular observation periods, were counted. The results are shown in the graph below.

The mountain yellow-legged frog (Rana muscosa) was once a common inhabitant of the Sierra Nevada (California, USA). It has declined during the past century due in part to the introduction of non-native fish, such as trout, into naturally fish-free habitats. The bar chart shows the average number per lake of tadpoles (aquatic larval stage) and frogs in lakes with and without trout in 1996.

The Asian shore crab (Hemigrapsus sanguineus) is an invasive invertebrate species found along the French coast. It preys on another invasive species, the amphipod Ptilohyale littoralis, and also on the blue mussel (Mytilus edulis), a native species. Scientists studied the relationships between the species.

In order to study which prey is preferred by the crabs, each crab was put into a tank for 12 hours containing only one species of prey at a time (no choice) or containing both species at the same time (choice). 15 crabs of each sex were tested. The graphs show the mean number of prey consumed by male and female crabs.

Native oyster populations are decreasing where rivers meet the ocean along the northwest coast of North America. These oyster populations are being attacked by a gastropod.

It is known that oysters and gastropods have hard parts composed of calcium carbonate and that ocean acidification is increasing. Studies were carried out using juvenile oysters and gastropods to investigate the effects of acidification on the decrease in the population of oysters.

The first step was to raise oysters in two different mesocosms. One had seawater at a normal concentration of $\mathrm{CO}_{2}$ and the other had sea water with a high concentration of $\mathrm{CO}_{2}$. Gastropods were raised in two further mesocosms with normal and high $\mathrm{CO}_{2}$ concentrations respectively.

Beavers are large rodents that live in waterways throughout the northern hemisphere. Dams made by beavers change the temperature of the streams and affect the mayfly, Baetis bicaudatus. In the summer of 2008, beaver ponds in West Brush Creek and Cement Creek, Colorado, were studied to evaluate their impacts on mayflies. The study sites included streams flowing into (upstream) and out of (downstream) each beaver pond.

Mayflies, including the species B. bicaudatus, are aquatic insects that hatch and spend their larval stages in water emerging from the water as adults. Larger females produce an increased number of better quality eggs.

A group of nine semi-wild Asian elephants (Elephas maximus) from an elephant camp in Myanmar were trained to pull two ends of a single rope to get access to food in food trays located on a table behind a barrier. When both elephants pulled the rope, the table moved towards them making the food trays accessible. The task required two elephants to work together in cooperation for mutual benefit to obtain food.

The graph shows the rate of cooperation between pairs of elephants in pulling the rope when there were two food trays, one at each end of the table (as shown in the diagram), or when there was one food tray placed in the centre of the table. The cooperation rate was the number of successful cooperative attempts divided by the number of all attempts in one session. The experiment was repeated for many sessions on successive days.

A study was conducted on the presence of a form (isotope) of carbon, carbon- $13\left({ }^{13} \mathrm{C}\right)$, in trees at four different altitudes of Lushan, a mountain in central subtropical China.

Samples of fresh leaves and leaf litter (dead leaves on the ground) were taken from altitudes between 219 m and 1268 m . The carbon isotope in the leaves was measured in each sample. Presence of the carbon isotope was measured to indicate the relative uptake of carbon dioxide in photosynthesis.

The distribution of native grasses in a temperate arid region of Mendoza, Argentina, was studied in six habitats (I to VI) at different altitudes. The table shows the presence (+) or absence (-) of the species in each habitat.

White sage (Salvia apiana) is a native Californian shrub. Slender oat (Avena barbata) is a grass, originally from the Mediterranean, which was introduced to California. The map shows the distribution of the two species in relation to one another in an area near Santa Ynez, California.

Using the scale bar, determine the area of quadrat A1, giving the units.