B4 - It's a green world

An ecosystem is made up of all the plants and animals living there.

Where a plant or animal lives is its habitat.

All animals living in a community make up its population.

Biodiversity means a large variety of plants and animals living there.

Antificial enivronments like fish farms have poor biodiversity, this is because humans will remove all competition by killing of natural predators and competitive species to increase yeild.

A transet line is performed to show the zonation in the distribution of organisms. This zonation occurs due to abiotic factors. Factors which a non-biological. To perform a transet line: a long length of string is placed across an area. At regular intervals a quarat will be placed down, the organisms in the quarat will be counted. If animals : number. If plants : percentage coverage.

Esitmated population size = number in first sample x number in second sample

                                                / number in second sample previously marked

However this method is only an estimate and doesn't account for death, reproduction, migration, non-identical sampling methods, marking affecting survival or the animals not falling for the same trap twice.

If you have a bigger quadrat size and more samples your estimation will be more accurate.

To draw a kite diagram:

Make a middle axis and then half your data and plot it symetrically on both sides.

6CO2 + 6H2O -> C6H12O6 = 6O2

Glucose made in photosynthesis:

-can be used in respiration to make energy.

-converted into cellulose to make cell walls.

-converted into protiens for growth and repair.

-converted into starch, fats and oils for storage.

Starch is used for storage in cells because it is insoluable and cannot move from storage areas. Unlike glucose it does not affect the water concentration of cells and casue osmosis.

Photosynthesis is a two stage process: 

-Water is split up by high energy releaseing oxygen gas and hydrogen ions.

-Carbon Dioxide gas combines with the hydrogen ions  producting glucose and water.

Greek scientists believed that plants took minerals out of the ground.

Van Helmont concluded, from experiments on growing a willow tree, that plant growth must depend on something other than soil minerals.

Priestley's expeirments showed that plants produced oxygen.

Modern experiments using a green algea called Chlorella and an isotope of oxygen 18O as part of a water molecule, have shown that the light energy is used to split water, not carbon diozide. The water is split up into oxygen gas and hydrogen ions.

Increased by: more CO2, more light, a high temperture with increased enzyme action.

Plants respire constantly, taking in oxygen and producing CO2 but this is only noticable at night as the gas exchange is smaller in terms of quantity than photosynthesis.

Limiting factors limit the rate of photosynthesis as they are needed for photosythesis. Eg. light, carbon dioxide

The leaf has an interesting structure. The cuticle is at the top, its waxy. Under that is the upper epidermus, which is trasparent becasue it lacks chloroplasts so that the next layer, the upper palisade layer will get most of the light (it has lots of chloroplasts).

Under these layers there is the spongy mysophill that has lots of air spaces so that the diffusion of gases between cells and the outer atmosphere can take place. It also creates a large surface area to volume ratio so that diffusion can occur faster. The stomata are on the bottom of the leaf.

Leaves are adapted: broad (large surface area), thin (diffusion of gases and penetration of light), trasparent (light), contain chlophyll (photosynthesis), network of vascular bundles (viens) for support and trasport of chemicals such as H2O and glucose. 

Guard cells control the opening and closing of the stomata. When the guard cells detect sunlight (daytime) they will start to photosynthesise, making glucose, since glucose affects the water concentration of the cells then therefore the water will osmose into the guard cell causing it to become tugid and inflate. This inflation causes the stomata to open as the guard cells curve to form a hole. This lets the air get into the spongy mesophyll.

By having many pigments (chlorphyll a and b, carotene and xanthophylls) the leaf can absorb lots of diferent wavelengths and therefore maximise the sun's energy.

Nitrates -> Nitrogen -> amino acids -> proteins

Phosphate -> phosphorous -> which are involved in respiration and growth ->used to make DNA and cell membranes. (sugar phosphate backbone)

Potassium compounds -> Potassium -> which are involved in respiration and photosynthesis. -> helps enzyme action

Magnesium compounds -> which are involved in photosynthesis. -> make chlorophyll

Lack of nitrates causes poor growth and yellow leaves.

Lack of phosphate causes poor root growth and discoloured leaves.

Lack of potassium causes poor flowers and root growth and discoloured leaves.

Lack of magnesium causes yellow leaves.

Minerals in soil are usually present in soil in low quanitites.

Minerals are taken up by root hair cells by active transport rather than by diffusion or osmosis. A system of carries transports selected minerals travel across the cell membrane. Active transport enables minerals, present in the soil in low concentrations, to enter root hairs already containing higher amounts of minerals. The uptake of minerals against the concentration gradient requires energy from respiration. 

Remeber: root hairs absorb water not roots.

Detritorvores feed on dead and decaying material (detritus).

Saprophytes are organisms that feed on dead and decaying material. They live on or in dead stuff.

They increase the rate of decay by increaseing the surface area and breaking it apart for further microbial breakdown. The rate of decay is increased by: higher temperatures, more oxygen and more water (humidity).

The optimium temperature for bacteria is 37C degrees. The optimium temperature for fungi is 25C. Higher temperatures mean denatured enzymes.

Increased Oxygen -> Faster rates of aerobic respiration -> Faster growth and reproduction

Increased Water -> More efficient digestion -> Faster growth and reproduction

Fungi produces enzymes to digest food outsdie their cells and then reabsorb the simple soluble substances. This is called extracellular digestion.

Canning -> heated & vacuum -> no bacteria or oxygen

Freezing -> slows down bacterial/fungal growth

Drying -> no water -> cannot feed or grow

Salt and Sugar -> kill some bacteria and fungi -> high osmotic concentration -> removes water from cells

Vinegar -> kills most bacteria and fungi -> high acidity 

Disadvantages of pesticides:

-Bioaccumilation causing a lethal dose for the predator

-Harms other organisms that are not pests

-Some are persistent (take a long time to break down and become harmless)

Organic Farming -> doesn't use artifical fertilisers or pesticides INSTEAD animal manure or compost. Also crop rotation that includes nitrogen-fixing crops. Also varying seed planting times to get longer crop time and avoid certain times in the life cycles of pests.

Organic farming avoids expensive fertilisers and their disadvantages HOWEVER the crops are smaller and the produce more expensive. (believed to be healthier and tastier)

Biological control -> using organisms to control pests eg. falcons to kill pigeons

Once introduced these organisms don't need replacing unlike pesticides. HOWEVER they could eat other useful species, they may reproduce too much and become pests themselves and spread. eg. Cane toads in Austrialia. They can also drastically change the food web of a habitat.

Intensive farming is a highly efficient system that can produce a high yield relatively cheaply using artilifcal pesticides and fertilisers. However animals cruelty and overworking/too many chemicals in soil. It improves the efficiency of the energy transpher in the food chain by removing competition such as pests and weeds. Also since the animals are inside they waste less energy on keeping warm/moving and therefore can concentrate more energy on growth/egg production.

Hydroponics is a system that doesn't use soil. A regulated and recyled flow of aerated water with dissolved minerals is used instead. Better control over mineral levels and disease, it's space efficient.