4.1 Adapt to survive
Organisms rely on materials from their surroundings and other living organisms, in order than they can successfully survive to reproduce. All living organisms have adaptations (special features that make it possible to survive in their habitat).
Plant adaptations: To produce their glucose for energy and growth, plants need to photosynthesise. They also need to have enough water to maintain their cells and tissues. Plants are adapted to live in a wide variety of places. Most plants get their required water and nutrients through their roots.
Animal adaptations: Animals get their food by eating plants (herbivores) or other animals (carnivores). Herbivores have teeth for grinding up plant cells; carnivores have teeth adapted for tearing flesh or crushing bones. Animals are also often adapted to attract a mate.
Extremophiles - Organisms that survive and reproduce in the most extreme conditions.
For example, bacteria called thermophiles survive at temperatures up to 80 degrees, whereas normally enzymes denature at 40 degrees.
4.2 Adaption in Animals
Animals in cold climates need to keep warm to survive. Common adaptations are:
- Having a large volume and a small surface area as this helps to retain heat. The ratio of surface area to volume falls as the object gets bigger
- Thick layers of insulating fat or blubber, which can also provide a food supply when there is little food in winter
- A thick fur coat
Animals are also often camouflaged so they cannot be seen to their prey, and so they cannot be seen by their predators.
Animals in hot climates like deserts include:
- A larger surface area and a smaller volume helps lose heat through their skin
- Thin fur
- Little body fat
- They are active in the cool evenings instead of the hotter days
- They are adapted to need little water and to get all the water they need from their food.
4.3 Adaption in plants
Plants take in water from the soil through their roots. It travels up the plant and into the leaves through small openings called stomata in their leaves. These can open to allow gases in and out for photosynthesis.
The rate at which a plant loses water is linked to the conditions it is growing in. When it is hot and dry, photosynthesis and respiration take place quickly.
To stop water loss through the leaves, the surface area: volume ratio is key. For example, desert plants have broad leaves with a large surface area, to collect the dew that forms in cold evenings. This water is then funnelled down towards their shallow roots.
To survive in dry conditions, many plants have extenstive root systems to allow them to obtain as much water as possible from the soil. Some can store water in their tissues.
4.4 Competition in animals
The most successfully adapted organism is most likely to win the competition for resources, and can survive to produce healthy offspring.
Animals compete for food; territory and mates.
Competition for food: Herbivores feed on many types of plants so they do not risk extinction if something happens to their food source; carnivores are adapted to have long legs to run fast and sharp eyes to spot prey; and prey animals compete to be the one that isn't caught.
Competition for territory: Most animals cannot successfully reproduce if they have no territory.
Competition for a mate: The male animals often try to impress the females - such as the peacock's display of feathers. In some species, like lions and deer, the males fight between themselves.
A successful competitior is an animal that is adapted to be better at finding food or a mate than the other members of its own species.
4.5 competition in plants
Plants compete for
- light for photosynthesis to make food using energy from sunlight
- water for photosynthesis and to keep their tissues rigid and supported
- nutrients/minerals to make chemicals required for cells
- space to grow, allowing their roots to spread and their leaves to capture light
Plants can compete successfully by having different types of roots. Some have shallow roots which take water and nutrients from near the surface of the soil. Others have long, deep roots, which go far underground.
Some plants are adapted to prevent animals from eating them.
Spreading the seeds: A plant has to avoid competition with its own seedlings to reproduce successfully. Many plants use the wind; some have sticky fruits or burrs to get caught up in the fur or feathers of an animal, which are then carriesd around.
The plants which grow fastest will compete successfully agains the slower plants.
4.6 How do you survive?
Non-living factors (e.g. average temperature or the average rainfall) hugely affects what can survive in a particular environment. Light, pH and the climate also influence where a particular organism can be found. For example, the oxygen levels in water is closely linked to the distribution of different species. Salmon are only found in water with a large quantity of dissolved oxygen.
When the non-living factors of an environment change, this imapcts the distribution of living organisms. For example, the average temperature may rise or fall, the amount of sunlight may change; the amount of sunlight or the average rainfall may change.
Living factors also affect distribution, e.g. if a new type of predator moves into an area; or a new pathogen wipes out a species.
Environmental change can be measured by using non-living indicators. The changing distribution of living organisms can be used as an indicator of environmental change. Lichen are very sensitive to air pollution and the more polluted the air, the fewer lichen species there will be. So a field survey on the numbers and types of lichen can be used to give an indication of air pollution.