Describe the use of Quadrats as a technique for sampling the distribution of organisms in their habitat

- Going to use Quadrats to take the population of daisy's on each side; grazed and ungrazed.

Sample has to be random so it's not biased, and it also has to be representative. Because of this we have to take a sample large enough that our estimate of the population will be as close to the true population as possible.

- The easiest way to do this is to plot a grid on a drawing/map of the land. Then have some random numbers to generate the x and y values. Lets say for example the numbers generated are (x, y) 3, 3

- Then the Quadrat will be placed at the coordinate 3, 3. Then the number of daisy's in that Quadrat must be counted and put into a table.

- This is 1 Quadrat done, but to get the best and most reliable results we would ideally want 10 Quadrats done. or more accurately at least 10% of the actual area of the land.

- Once the 10 Quadrat values have been put into a table then we would add up the number of daisy's and divide by the number of quadrats. This would give us the value of the number of daisy's per meter square.

Recall the use of Quadrats to estimate the population size of an organism in two different areas


- This is a photo of a Sand Dune Ecosystem which is made up of a number of populations which form the community. The habitat is shown below and is split in two different areas by a fence. One side which is grazed by cattle and one side which is ungrazed.

- So we have to different areas within an ecosystems and could choose to study the population on either side. We could do this by counting the number of individuals in the population. The technique is called 'Quadrating.' Based on squares hence the word "Quad". These squares can be made of any material (wood, string, metal) to form a square grid.

- The Quadrat is used to take a sample of the population in a selected area. This is done by laying down the Quadrat and counting the number of individuals inside the square. If this is done for every square in the area, it can be used to gain an estimate of the population size.

- To summarise Quadrats are a method of sampling different locations so populations can be compared.

Understand the terms: Population, Community, Habitat and Ecosystem

An Ecosystem is a Community of Organisms in a particular Habitat. The Community is made up of different populations of the different species interacting within that habitat.

- Habitat includes all the "Abiotic" factors (non biological factors)
eg. cycle of daylight with dark, temperature (local or seasonal), rainfall, humidity, geology (slope of the land)

- Community of Organisms is made up of populations of different species and they are all interacting.
Population is the number of individuals of a particular species.
And species are organisms that reproduce to give fertile offspring.

Plant Fertilisation Practice Test

Plant Fertilisation

- When the pollen grain sticks to the stigma, it begins to germinate causing a tube to grow named a pollen tube. It descends down the stigma, through the carpel and into the ovule. Each pollen grain has its own pollen tube.

- The pollen nucleus fertilises the ovule, which will lead to the formation of a zygote. This will then turn into the embryonic plant.  In addition to this Cotyledons are formed, which are food stores for the seedling. They support the plant until it develops its first set of leaves.

- The outside of the ovule forms a seed coat, or a TESTA

- Another thing that occurs, is the thickening of the walls of the ovary/carpel. The plant will put energy into building up sugars and proteins in the ovaries/carpel, which produces fruit.

Wind Pollination

- For the process of pollinating a flower there has to be a transfer of pollen grains from the anthers of one plant to the stigma of another, through air carried by the wind.

- In wind pollination it is unnecessary for the plant to have a nice appearance and scent because it doesn't need to attract insects. Because of this it has no nectaries because that would be a waste of energy. The wind moves the pollen from the anther of one plant to the stigma of another.

- First adaptation to have light pollen grains, possibly a wing feature to help them glide through the air efficiently. 

- Second adaptation is to have anthers that hang well away from the basic flower structure to expose them to the wind more. This is so it is easy for the wind to pick up the pollen grains.

- Third adaptation is for the stigma to have a large surface area, similar to the end of a feather.

Insect Pollination

- For the process of pollinating a flower there has to be a transfer of pollen grains from the anthers of one plant to the stigma of another. This is known as Cross Pollination.

- Pollen contains the male nuclei, and is transferred to the stigma of other plants by insects.

- Because of this it is necessary for the plant to attract insects to it. It does this by either making itself look appealing (coloured petals - insects react well to this), or smelling good. Also a value to the insect of going to the flower, which is provided using food by the nectaries. The nectaries produce fructose which the insect uses as a source of protein.