B4 Flashcards
Describe a natural ecosystem?
- natural ecosystems have BIODIVERSITY
> many different species of plants and animals coexist in the same environment
What is an ECOSYSTEM?
- a physical environment with a particular set of conditions, plus all the organisms that live in it
Describe an artificial ecosystem?
- e.g. Greenhouses
- designed and maintained for a particular purpose so they have low biodiversity
What are the affects of weed killers, fertilisers and pesticides in an artificial ecosystem?
- they prevent other animals and plants from growing alongside the crop
- leads to low biodiversity
Describe FORESTRY PLANTATIONS?
- very carefully set up, controlled and monitored.
- have less biodiversity due to the fact they aren’t as old as natural woodlands, which take years to form and result from the relationships and interactions of the organisms that live there and around.
- fewer species are introduced, and not all will survive from the start
What is a community?
- the total number of individuals of all the different populations of plants and animals in a habitat at any one time
What is a POPULATION?
- the total number of individuals of the same species that live in a certain area
What is the only thing that Ecosystems rely on?
- their energy source, the sun
Name 4 sampling methods used to measure the size and distribution of population?
- pooters
- sweep nets
- pitfall traps
- quadrats
How do pooters work?
- the are containers which suck in organisms without harming them
How do sweep nets work?
- used to collect insects in long grass or moderately dense woodland where there are lots of shrubs
How do pitfall traps work?
Pitfall traps are containers set into ground that are used to catch small insects
How do quadrats work?
Quadrats are square frames that have sides 0.5m long. They are used to count a smaller, representative part of a population.
What must you make sure of when sampling?
- you take a big enough sample to make the results a good estimate
- you sample randomly, the more random the sample the more likely it is to be representative of the population
What is Capture-recapture (Lincoln index)?
A method used to estimate a population size
How does capture-recapture work?
1- A trap is used to catch a sample of individuals
2- the sample is counted and recorded and each individual is marked with a number tag/band or a dot of paint
3- the individuals are released, unharmed into the environment, and are given time to redistribute themselves
4- another sample is taken, some of them are marked, some aren’t.
How can you estimate population size from capture-recapture?
Population size =
No. In 1st sample ✖️ number in 2nd sample
➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖
No. In 2nd sample already marked
When using capture-recapture, what do you have to do?
- make sure no organisms have died, immigrated or emigrated between sampling
- make sure that identical sampling methods are used from one visit to the next
- make sure the marking of the organism doesn’t harm them
What is a transect line used for?
- used to map the distribution of organisms
- used for studies of how species change across a boundary between habitats
What is ZONATION?
- the gradual change in the distribution of species across a habitat
What does photosynthesis produce?
- glucose for biomass and energy. Oxygen is produced as a by-product
What is the equation for photosynthesis?
Carbon dioxide➕water ➡️ glucose ➕ oxygen
What can glucose and starch be converted into?
- energy (during respiration)
- proteins for growth and repair
- starch, fats or oils that can be stored in seeds
- cellulose, which is needed for plant cell walls
Describe Glucose?
- glucose is soluble, it can be transported around a plant as soluble sugar, but it must be converted It to starch, which is insoluble to be stored
Describe starch?
Starch is a very useful, strong molecule.
It is insoluble which means it doesn’t affect the water concentration inside cells when stored, it also does not move away in soloutions.
What have scientists used radioactive oxygen-18 to discover?
- that the oxygen produced in photosynthesis as a by-product, comes from the water and not the carbon dioxide.
- only when oxygen-18 is introduced via the water do you get a radioactive waste product of oxygen.
- it shows that photosynthesis is a two-stage process.
Describe the two stages of photosynthesis?
1- light energy is used to split water, releasing oxygen gas and hydrogen ions.
2- then the carbon dioxide gas combines with the hydrogen to make glucose
How can photosynthesis be increased?
- increasing the temperature
- increasing the light intensity
- increasing the carbon dioxide concentration
What happens in photosynthesis when the temperature rises?
- as the temperature rises so does the rate of photosynthesis.
- this means that temperature is the limiting factor in the rate of photosynthesis.
- as the temperature approaches 45, the enzymes controlling photosynthesis start to denature and the rate of photosynthesis declines to zero
What happens in photosynthesis when the concentration of carbon dioxide rises?
- so does the rate of photosynthesis.
- carbon dioxide is limiting the rate of photosynthesis up to a certain point.
- after this point, a rise in carbon dioxide levels has no effect.
- carbon dioxide is no longer a limiting factor
What happens in photosynthesis when the light intensity increases?
- so does the rate of photosynthesis
- the light intensity is limiting the rate of photosynthesis up to a certain point, when light intensity has no further effect
Describe a leaf?
- contains a pigment CHLOROPHYLL, (which absorbs light) in millions of chloroplasts, plus other pigments to absorb light from different parts of the spectrum.
- is broad and flat to provide a huge surface area to absorb sunlight
- has a network of vascular bundles for support and to transport water to the cells and remove the products of photosynthesis, ie. glucose
- has a thin structure so the gases only have a short distance to travel to and from the cells
- has stomata (tiny pores) on the underside of the leaf to allow the exchange of gases; these are opened and closed by guard cells
What does carbon dioxide do during photosynthesis?
- carbon dioxide diffuses in through the stomata (leaf pores)
What does oxygen do during photosynthesis?
- oxygen diffuses out through the stomata