Remote sensing satellites are used to monitor the Earth's ecosystems. One measure of ecosystem status is leaf area index (LAI), which is the total area of leaves in square metres per square metre ( $\mathrm{m}^{2} \mathrm{~m}^{-2}$ ) of the Earth's surface. The graph shows LAI estimates, calculated using data from the Global Inventory Monitoring and Modelling System (GIMMS), during the period from 1981 to 2011. The data points are monthly averages in four latitudinal zones in the northern hemisphere.

Global warming has changed both the thickness and surface area of sea ice of the Arctic Ocean as well as the Southern Ocean that surrounds Antarctica. Sea ice is highly sensitive to changes in temperature.

Scientists have calculated a long-term mean for the surface area of sea ice in the Arctic and in the Southern Ocean around Antarctica. This mean value is used as a reference to examine changes in ice extent. The graph shows the variations from this mean (zero line) over a period of time.

Coral reefs are among the most spectacular ecosystems on Earth. They support a rich diversity of life and provide economic benefits to the people who use them. In Papua New Guinea in the Pacific Ocean north of Australia the following data were collected. Coral cover is the percentage of the reef surface covered by live hard coral.

PanI is a gene in cod fish that codes for an integral membrane protein called pantophysin. Two alleles of the gene, $\operatorname{PanI}{ }^{\mathrm{A}}$ and $\operatorname{PanI}{ }^{\mathrm{B}}$, code for versions of pantophysin, that differ by four amino acids in one region of the protein. Samples of cod fish were collected from 23 locations in the north Atlantic and were tested to find the proportions of PanI ${ }^{\mathrm{A}}$ and PanI ${ }^{\mathrm{B}}$ alleles in each population. The results are shown in pie charts, numbered 1-23, on the map below. The proportions of alleles in a population are called the allele frequencies. The frequency of an allele can vary from 0.0 to 1.0 . The light grey sectors of the pie charts show the allele frequency of PanI ${ }^{\mathrm{A}}$ and the black sectors show the allele frequency of PanI ${ }^{\mathrm{B}}$.

Bottlenose dolphins (Tursiops truncatus) inhabit almost all tropical and temperate oceans between $45^{\circ} \mathrm{N}$ and $45^{\circ} \mathrm{S}$. Over a two-year period, aerial surveys were carried out to investigate the seasonal distribution of these animals along the mid-Atlantic and eastern coastal waters of the USA. Sightings were recorded using a global positioning system (GPS) while flying parallel to the coast approximately 500 m offshore. The diagram below shows a map of the section of coast surveyed. The bar graph shows the seasonal data for summer and winter at the corresponding latitudes ( ${ }^{\circ} \mathrm{N}$ ). A total of 5431 bottlenose dolphins were sighted during these surveys.

The black-legged tick (lxodes scapularis) is an arthropod which sucks blood from humans and other mammals. It is encountered mainly in wooded and semi-wooded areas.
Some ticks can be infected by the bacterium Borrelia burgdorferi. When a tick bites a human, the bacterium is often introduced, causing Lyme disease. Lyme disease is a public health problem in North America and, if left untreated, can cause important neurological impairment. The diagram represents the two-year life cycle of a tick.

Average human internal (core) body temperature is $36.4^{\circ} \mathrm{C}$, with slight variations between day and night. The average surface temperature of the Earth in the 20th century was $13.9^{\circ} \mathrm{C}$. It has now risen to $14.8^{\circ} \mathrm{C}$.

E1. European robins (Erithacus rubecula) migrate South in the autumn (fall) and North in the spring. They orient their direction of flight using the local magnetic field, which they detect through magnetoreceptors in the upper beak. The orientation of the birds in a captive environment was studied in spring and autumn, which are the times of year when the birds normally migrate. The response of the birds to green light, red light and total darkness was investigated. Triangles on the edge of circles indicate the mean direction flown by individual birds while the arrows indicate the overall mean direction of flight.

The graph shows the mean annual changes in global temperatures between 1880 and 2014. The mean temperature from 1951 to 1980 was used as the value of zero change in temperature.