Biology B1 (Interdependence and adaption)

Every organism has certain features or characteristics that allow it to live successfully in its habitat. These features are called adaptations, and we say that the organism is adapted to its habitat. Organisms within a community compete with each other for limited resources, including water and space. Plants also compete with each other for light and minerals.

The meaning of key words used to describe adaptations

WordMeaning Environment all the conditions that surround a living organism Habitat the place where an organism lives Population all the members of a single species that live in a habitat Community all the populations of different organisms that live together in a habitat Ecosystem a community and its habitat

Habitats have limited amounts of the resources needed by living organisms and organisms can only survive if they can get enough of these resources, so they must compete for resources with other organisms. If they are unsuccessful and cannot move to another habitat, they will die.

The resources that animals compete for include:

• food
• water
• space
• mates

The resources that plants compete for include:

• water
• space
• mineral salts.

Cold climates

The Arctic is cold and windy with very little rainfall. Plants in the Arctic often grow very close to the ground and have small leaves. This helps to conserve water and to avoid damage by the wind.

The polar bear is adapted to life in a cold climate

Polar bears are well adapted for survival in the Arctic. Their adaptations include:

• a white appearance as camouflage from prey on the snow and ice
• thick layers of fat and fur for insulation against the cold
• a small surface area to volume ratio, to minimise heat loss
• a greasy coat that sheds water after swimming
• large furry feet to distribute their load and increase grip on the ice.

Hot climates

Camels live in deserts that are hot and dry during the day, but cold at night. Their adaptations include:

• large, flat feet to spread their weight on the sand
• thick fur on the top of the body for shade, and thin fur elsewhere to allow easy heat loss
• a large surface-area-to-volume ratio to maximise heat loss
• the ability to go for a long time without water - they don't store water in their humps, but they lose very little water through urination and perspiration
• the ability to tolerate body temperatures up to 42ºC
• slit-like nostrils and two rows of eyelashes to help keep out sand.

Desert plants

Cacti are well adapted for survival in the desert. Their adaptations include:

• stems that can store water
• widespread root systems that can collect water from a large area.

In addition, cacti have spines instead of leaves. These minimise the surface area and so reduce water loss by transpiration. The spines also protect the cacti from animals that might eat them.

Extremophiles

Extremophiles are organisms that live in very extreme…