GCSE OCR Gateway Science B2

Sampling Techniques - These only give an estimate of numbers becasue populations change all the time.

Pooter- collect small inseccts, arthropods, from tree bark, under stones, etc.

Pitfall trap - placed at ground level baited, collects surface dwellers - carnivores can eat herbivores

Quadrats - estimate plant species

• placed randomly
• placed a number of times
• average number found for each quadrat

Capture and Release - no. of animals caught 1st time * no. of animals caught 2nd time

no. of marked animals caught 2nd time

Ecosystem - a place or habitat together with all the organism that live there.

Population - the number of inhabitants in a place or habitat

Natural Ecosystems - have many dffferetn species living them and a high biodiversity

Artifical Ecosystems - usually have a lower biodiversity and pesticides, weedkiller and fertilisers are used

Characteristics that place an organism into the animal kingdom :

• They can move independently
• They do not have chloroplasts
• They cannot make their own food
• They are more compact, this helps with movement

Characterstics that place an organism into the plant kingdom :

• They cannot move independently
• They contain chloroplasts, which makes them green
• They can make their own food
• They spread out more, because they cannot move

Fungi and Euglena cannot be placed into one of these groups due to characteristics.

Animals can be divided into two groups :

• Vertebrates - animals with backbones
• Invertebrates - animals without backbones

Vertebrate animal groups have very different characteristics :

• Fish have wet scales and gills to get oxygen from the water
• Amphibians have a moist permeable skin
• Reptiles have dry scaly skin
• Birds all have feather and beaks but not all of them can fly
• Mammals have fur and produce milk

Organisms are further divided until there is only one type of organism in the group. This group is a species. every species has two names. This way of naming species is called the binomial system. Hybrids are the result of breeding two animals from different species.

Photosynthesis

When green plants make food (sugar) using light energy

Glucose is stored as insoluble starch so the substance cannot leave the cell which is very useful.

Glucose is used in respiration for energy, and is converted to :

• sucrose - how the sugars are transported around the plant
• starch - how the sugar is stored
• cellulose - forms the cell walls
• oils - storage in the seeds
• proteins - cell growth

The limiting factors for photosynthesis are :

• sunlight
• carbon dioxide
• temperature

If the plant is getting enough of the other two limiting factors but not enough of the third factor, then this is the limiting factor, it is controlling the rate of photosynthesis.

How fossils are formed -

they are often formed from hard parts of living things. If dead animals are covered in sediment and buried, the hard parts are replaced by minerals which turn to stone, forming a fossil.

Why the fossil record is incomplete -

• Conditions not always right to form fossils
• Some fossils not found
• Some fossils destroyed
• Not all body is fossilised, soft organs decompose before fossilisation

Natural Selection

• Within any species there is variation
• Organisms will produce more young that will survive
• There will be competition for limited resources e.g. food
• Only those best adapted will survive
• Those that survive pass on their successful adaptation to the next species
• When different species are competing, the less well adapted species may become extinct

The peppered moth was seen by predators so it adapted so it would be camoflauged against the habitat.

Rats were poisoned by Warfarin so now they are becoming resistant.

Bacteria is becoming immune to antibiotics instead of being destroyed.

Indicator Species

Some species can tolerate low oxygen levels present in polluted areas, others need clean water

e.g. mayfly larva that need high oxygen levles.

Lichens are also an indicator species as these survive in clean and not polluted air.

Extinct - when all members of the species have died

Endangered - numbers are so low it is difficult for population to rise due to destruction of habitat, natural disasters or hunting

Conservation - protecting endangered species

Sustainability - making sure our natural resources don't die out

Sustainable Development - meet human demand whilst conserving the environment

• fishing quota
• whales bred in captivity
• if woodland is cut down, it is replaced

Sustainable Development

As the world population grows, more and more resources are being used up. The demand for food and energy is constantly growing. We are producing more waste products and we have less land to dispose of them.

In order to maintain this growing population, feed them and dispose of their waste, we must encompass sustainable development.