4.4 Trophic Levels

-Trophic means to feed

Photosynthesis Herbivore Carnivore Top Carnivore

Producer Primary Consumer Secondary Consumer Tertiary Consumer

Light energy-> Plant chemical energy-> Chemical energy-> Chemical energy->

chemical energy animal chemical energy Chemical energy Chemical energy

All organisms die and are then broken down my decomposers eg. Funghi and bacteria. These break down complex molecules into nitrates and phosphates.

4.3 Quadrates samples

Wes use quadrates to find the population of certain species, in this case daisies. The sample must be random so there is no bias. It must also be representative.

The sample has to be large enough so that the estimate of the population is as close as possible to the real population.

4.2 Quadrates

The image shows a Sand Dune ecosystem which is made up of a number of populations which form the community and the habitat.

There is a fence which splits the Sand Dune region into grazed by cattle and ungrazed.

So there are two different types of areas within an ecosystem and we can choose to study both populations.

The first step is to count the number of individuals in the population. The technique used to do so is called quadratic. Quadrates are made up of squares and can be produced in any material such as wood, metal or string forming a square grid.

These square grids are used to sample the populations of different areas. By counting the number of individuals in the grid, and repeating this numerous times, we are able to gain an estimate of the population.

4.1 Ecosystems

An ecosystem is a community of organisms in a particular habitat.

The study of habitat is non biological (abiotic factors) eg:

-Cycle of daylight/dark (photo period)

-Temperature (local/seasonal/annual)

-Rainfall

-Humidity

-Slope of the land

The community is made up of populations of different species and their interacting with each other. Population is the number of individuals of a particular species. Species are organisms that reproduce to give fertile offspring. The main type of interacting is: Feeding.

Summarise:

Ecosystem-community of organisms in a particular habitat-community of different species interacting.

3.4 Plant Fertilisation

Pollen grains germinate, tube grows downwards. Germination happens with specific species, so only the same type of pollen can germinate. Male nucleus goes through the pollen tube down to the ovule.

In order for a seed to form, the following must happen:

-Fertilisation: Pollen nucleus + ovule= Zygote

-Coating: Outside ovule forms seed coating: TESTA

-Food stores for the seedling: Cotyledons (support plant till leaves come)

-Fruit: Ovary wall thickens, energy put into sugars proteins, which eventually form the fruit.

3.3b Wind Pollination

Through the movement of wind, pollen is transferred from the male part of the plant to another plant's female part.

In order for the pollen to be carried in the wind, it is made to be lightweight and has winglike features to help move effectively through air.

Also, the anthers will hang well clear of any flower structures so that they are exposed to the wind.

The stigma will have a large surface area, featherlike structure to catch the pollen grains as they pass through the wind.

The flower has no scent, no color or nectaries because it is a waster of energy as these features are not needed for wind pollination.

3.3a Insect Pollination

Cross-Pollination is the transfer of pollen (Male nuclei) from one plant to another plant's stigma (female part).

In order for a plan to be pollinated by an insect, the plant must attract the insect.

The plants colored petals and various scents are watch attract the insect, and the insect always returns because they receive fructose and pollen (protein).

Stamen (Male part of the plant):

Anther which produces pollen grains

Filament which supports the anther

Carpal (Female part of the plant):

Stigma is where pollen grains fall

Style which connects the stigma to the ovary

Ovary which contains eggs (ovules)