The Dead Sea is the most saline lake on Earth, with a salt concentration over 10 times higher than that of sea water.

It is such a harsh environment that only microorganisms from the Archaea domain are able to survive.

Salt concentration is an example of an abiotic factor that affects the growth of organisms.

State two other abiotic factors.

Give two biotic factors that affect the growth of organisms.

A healthy garden will support several species of ladybird.

The photograph below shows a ladybird.

Ladybirds are natural predators of greenflies, as represented in the food chain below.

oak tree  →  greenfly  →  ladybird  →  blue tit

Many of the ladybirds in the garden died.

Explain what is likely to happen to the number of greenflies in the garden.

Give two factors that may limit the number of ladybirds.

Population and community are terms used to describe the organisms in an area.

Describe the difference between the terms 'population' and 'community'.

The photograph below shows loggers cutting down trees in a forest.

Describe the effects of cutting down trees on the biotic and abiotic factors of the forest ecosystem.