Biology B4*
- Created by: Mollie Derhun
- Created on: 27-02-13 16:35
Fullscreen
Ecology in the Local Environment
Distribution of Organisms
- An ecosystem is made up of all plants and animals living there and there surroundings
- Where a plant or animal lives is called its habitat
- All the plants and animals living in the garden make up the community
- The number of a particular plant or animal living there is called its population
- Natural ecosystem have a large variety of plants and animals living there - it has good biodiversity
- Artificial ecosystems have poor biodiversity
- The distribution of organisms can be mapped using a transect line
- The data can be displayed as a kite diagram
- In artificial ecosystems, humans deliberatley keep and protect one species and remove any other animals that would compete with it/lower the yeild
- A trabsect line can show zonation on the distribution of organisms
- Changes in abiotic (not biological) factors cause zonation
- Food chains and food webs show that plants and animals are interdependant, with energy being transferred from one organism to another
- The exchange of gases in photosynthesis and respiration ensures an overall balance of these gases
- An ecosystem is self-supporting in all factors apart fom having to have the sun as an energy source
Population Size
- Population size can be estimated by obtaining data from a small sample and scaling up
- Population size = number in 1st sample x number in 2nd sample / number in 2nd sample previously marked
Photosynthesis
The chemistry of Photosynthesis
- 6CO2 + 6H2O = C6 H12 O6 + 6O2
- The sugars in glucose can be: 1) used in respiration, releasing energy 2) converted into cellulose to make cell walls 3) converted into proteins for growth and repair 4) converted into starch, fats and oils for storage
- Starch is used for storage because it is insoluble and does not move from storage areas. It does not affect water concentration and cause osmosis
- Photosynthesis is a two stage process: 1) water is split up by light energy releasing oxygen gas and hydrogen ions. 2) carbon dioxide combines with the hydrogen ions producing glucose and water
Historical understanding of Photosynthesis
- Greek scientists believed that plants took minerals out of the soil to grow and gain mass
- Van Helmont concluded that plant growth could not be only due to the uptake of soil minerals
- Priestly's experiment showed that plants produce oxygen
- Modern experiments using an isotope of oxygen show that light energy is used to split water, not carbon dioxide
The Rate of Photosynthesis
- It can be increased by the plant having : 1) more carbon dioxide. 2) more light. 3) a higher temperature which increases enzyme action
- Photosynthesis will only take place in the daytime
- Plants respire at all times by taking in oxygen and releasing carbon dioxide
- During the day they also carry out photosynthesis, taking in carbon dioxide and releasing oxygen
- The rate of photosynthesis is more that the rate of respiration
- Photosynthesis depends on light, temperature and carbon dioxide, a lack of one of these factors will limit the rate of…
Comments
No comments have yet been made