Biology, B2

All living things and their surrounding make up an ecosystem.

Many ecosystems are still unexplored and could contain new species.

Artificial Ecosystems - usually controlled using pesticides(control pests), herbicides (remove weeds) and fertilisers(increase crop yield)

Keys-can be used to identify the animals and plants in a habitat

Population- a group of plants or animals of the same species

Community- lots of different species living in the same ecosystem

Biodiversity- describes the range of living things in an ecosystem. eg a farmer decreases the biodiversity on his farm when he uses pesticides and herbicides

Different counting methods are used to estimate populations.estimates are often inaccurate if the sample size is not large enough. To increase accuracy- repeat the process, make the sample size as large as possible.

Quadrats- method of this. place on ground in a random way (fairness). Percentage cover of each plant is recorded.

population formula - no of animals 1st x no of animals 2nd

no of marked animals 2nd

Animal kingdon is split into two groups:

• Vertebrates- have a back bone
• Invertebrates- don't have a backbone

5 vertebrate groups:

• Fish- have scales and gills (get oxygen from water)
• Amphibians- have moist permeable skin
• Reptiles- have dry scaly skin
• Birds- all have feathers and beaks, but not all can fly
• Mammals- have fur, produce milk

Some organisms do not fit into the animal/plant kingdom

• Mushrooms-fungi-cannot move like animal, or make food like plant
• Euglena-protoctista-can make own food, can feed
• Archaeopteryx- bird and reptile characteristics, reptiles and birds linked.

Dolphins and whales are mammals. They have evolved to look like fish so they can live in water.

Hybrids are the result of breeding two different species. These are sterile and cannot breed. Therefore it is not a species and is difficult to classify. eg donkey and horse= mule

carbon dioxide + water glucose + oxygen

for storage, glucose joins together to make larger molecules of starch. starch is not very reactive (good storage molecule) and insoluble(not easily lost from the cell in solution)

To increase the rate of photosynthesis you can:

• Keep the plants warm
• Increase the amount of light
• Give the plants extra carbon dioxide

carbon dioxide, light intensity and temparature all limiting factors of ps

Uses oxygen to release energy from glucose. At the same time it releases carbon dioxide and water.

Plants carry this out 24hours at night and day! If they would stop respiring they would have no energy and die.

Need oxygen to respire. takes in oxygen from air and release carbon dioxide.

as long as a plant is photosynthesising it needs to take in carbon dioxide. at the same time it will release oxygen.

survival depends how well it can adapt to changes in the environment. The numbers of predators can affect population, numbers of prey vice versa. survival may also depend on the presence of another organism:

• Mutualism- This is when both species benefit from the arrangement. When an organism helps another organism of a different species, that also benefits themselves.
• Parasitism- when parasites live on or in a host organism. The parasite benefits from this arrangement, but the host suffers as a result.

an 'up and down' pattern of population change is called CYCLIC FLUCTUATION

an indicator species is used to monitor pollution levels

Charles Darwin- developed the theory of natural selection

• in any species there is variation
• will be competition for limited resources such as food
• those best adapted will survive (survival of the fittest)
• successful adaptations are passed to the next generation in genes
• the changes may result in a new species
• the less well adapted species may become extinct
  1. a giraffe's with a longer neck can reach food high up
  2. a giraffe is more likely to get enough food to survive to reproduce
  3. a giraffe's offspring inherit its long neck

Jean Baptiste de Lamarck

• different theory called the law of acquired characteristics
• was discredited, as acquired characteristics cannot be passed on by genes
  1. a giraffe stretches its neck to reach food high up
  2. the giraffe's neck gets longer because its used a lot
  3. the giraffe's offspring inherit its long neck