b2

B2 revision.

A habitat is the part of the physical environment where animals and plants live.

Population is the total number of individuals of the same species in a certain area.

Community- total number of individuals of different species living together in a habitat at any one time.

Ecosystem- a physical environment with organisms living in it. It has a particular set of conditions. They can be natural or artificial.

Natural ecosystems aren’t altered by humans such as woodlands. They have a high biodiversity (many different species coexist in the same environment).

Artificial ecosystems are completely man-made and carefully controlled to keep conditions constant such as green houses. They are designed for a particular purpose.

Weed killers and pesticides can be used in artificial ecosystems preventing biodiversity.

Methods of sampling…

Pooters- are containers which collect insects without arming them.

Sweep nets- are nets used for collecting insects from long grass.

Pitfall traps- containers set in the ground used to catch small insects.

Quadrats- square frames, thrown randomly, you count and record the number of species in the quadrat.

When sampling you have to make sure you take a big enough sample, the larger the sample the more accurate the results.

The more random the sample the more likely it is to representative of the population.

Comparing 2 habitats…

1. collect sample
2. count and record the population of each species
3. repeat above steps several times
4. large, reliable, random, sample
5. make quantitative estimates of the population size and distribution

Identifying species is easy because they have different characteristics.

Animals are compact- so they can move around easily; can’t make their own food; have a nervous system.

Plants can’t move around; have spreading shoots and roots; have chloroplasts so they can make their own food and have cell walls.

Fungi can’t move around; have spreading hyphae; they can’t make their own food.

Fungi are grouped in a different kingdom because they don’t have the characteristics of animals or plants.

Euglena are microscopic organisms which can photosynthesis but also move around. They don’t have characteristics of plants and animals.

Vertebrates…

Fish- have wet scales, and gills.

Amphibians- have moist permeable skin that allows them to absorb oxygen through their skin.

Reptiles- have dry scales preventing them loosing water on land.

Birds have a beak and feathers.

Mammals- have fur, and produce milk.

Species are groups of animals that share characteristics. Members of the same species are so similar they can reproduce together producing fertile offspring.

The binomial system is when each species is given 2 Latin names.

Between species there can be vast variation. Eg dogs are a species but there is differentiation between breeds.

The archaeopteryx is and extinct organism identified from fossils. It was hard to classify because it has both bird and reptile characteristics.

When organisms from different species mate they produce a hybrid which will be born infertile.

Species that live in the same habitat and compete for the same things will be similar.

Closely related species can be founding different…