A-Level CAIE Biology A2 18.2 Biodiversity Question Bank

The natterjack toad, Bufo calamita, is an endangered amphibian species in the UK. It comes out of hibernation in April and breeds in pools by sand dunes along parts of the UK coast. A young natterjack toad will take about 10 weeks to develop from a fertilised egg. A natterjack toad feeds at night, by running at its prey, mainly insects and worms, on the sand dunes.

Fig. 1.1 shows a natterjack toad.

The flatback turtle, Natator depressus, is an endangered species that nests on northern Australian beaches.

Fig. 1.1 shows a flatback turtle.

Each female lays approximately 50 eggs per nest, which is a smaller number than all other species of marine turtle. The eggs are buried in the sand and when the hatchlings emerge each has a mass of approximately 43 g . Unlike most marine turtles, flatback turtles spend most of their time in coastal waters. This is where they feed and mate.

Fig. 1.2 shows the numbers of female flatback turtles nesting on a beach in northern Australia between 1993 and 2002.
number of female turtles nesting

Fig. 1.1 shows a snow leopard, Panthera uncia. The habitat of the snow leopard is the high mountains of Central Asia.

Snow leopards usually live and hunt alone. Their main prey is grazing herbivores, such as wild sheep and wild goats. They will also hunt domesticated animals and livestock.

The number of snow leopards has decreased dramatically in the last 40 years.

The American crocodile, Crocodylus acutus, was classified as an endangered species by the USA in 1975. It is found in estuarine regions of southern Florida.

Fig. 1.1 shows an American crocodile.

The salinity of the water was thought to play a part in the distribution of the American crocodile.

Fig. 1.2 shows the number of American crocodile nest sites in areas with water of varying salinity in southern Florida.

The Great Lakes, in North America, lie between the USA and Canada. A survey of birds of the Lake Ontario area has shown the relative abundance of birds between 1995 and 2005.

Table 1.1 shows the feeding habits and the relative change in numbers of some of the birds in the survey.

The Bengal Tiger, Panthera tigris tigris, is an endangered mammalian species of Southern Asia. It lives mostly in a forest habitat.

Fig.1.1 shows a Bengal Tiger.

Corals are simple marine animals and usually exist in colonies of thousands of individuals.
Fig. 1.1 shows a coral colony.

Corals absorb calcium carbonate from the sea to build their skeletons, which help to form large coral reefs. Coral reefs provide a home for about 25 % of known fish species and have the highest biodiversity of any marine ecosystem.

Fig. 1.1 is a summary of energy flow in a forest ecosystem. The width of the arrows is proportional to the energy that flows between each component in the ecosystem.