Topic 10

Question 1

Ecosystem?

Answer 1

an environment including all the living organisms interacting within it, the cycling of nutrients and the physical and chemical environment in which the organism are living. They can range in size, i.e a desert or a rock pool.

Question 2

Trophic Level?

Answer 2

describes the position of an organism in a food chain or web and describes its feeding relationship with other organisms.

Question 3

Evaluation of pyramids of numbers

Answer 3

Represents the numbers of organisms at each trophic level in a food chain.
In most food chains the number of organism decreases at each trophic level.
But is some food chains cause the pyramid to be upside down.
It is the simplest and easiest way of representing a food chain.

Question 4

Evaluation of pyramids of biomass

Answer 4

Represents the biomass of the organisms at each trophic level in a food chain.
More realistic model as it shows the combined mass of all the organisms in a particular habitat.
using a dry mass eliminates the inaccuracy of variable water content in organisms, but is involves destroying the material.

Question 5

Evaluation of pyramid of energy

Answer 5

made up of observations over time, hence gives a more accurate model than a pyramid of number or biomass. (It considers the reproduction rate).
But very difficult to calculate.
The energy in ecosystems remains the same at every level. It is the size of the different type of energy stores that changes.
As you move along a food chain, less energy is stored in the organisms and more is stored in the surrounding atmosphere.

Question 6

Why are there energy losses as you move along a food chain?

Answer 6

not all organic matter is digested between the trophic levels. The energy in the fees passes to detritivores and saprotrophs.
Some material is not invested e.g the carcass
Much of the material that is digested is used to drive respiration, which result in the production of ATP. Hence this energy can not be passed on.

Question 7

Ecological techniques to assess abundance and distribution of organisms in a habitat

Answer 7

Quadrats: a square frame divided into sections that you lay on the ground to identify the sample area.
Line transects: a way of gathering data more systematically. A tape is stretched between two points and every individual plant that touches the tape is recorded.
Belt transect: when two tapes are laid out and the ground between them surveyed.
ACFOR Scale: a simple scale used to describe the abundance of a species in a given area.
Abundant, Common, Frequent, Occasional, Rare
Percentage cover: describes the area covered by the above ground parts of a particular species.
Individual counts: the number of individual organisms in an area.

Question 8

What is a t- test?

Answer 8

a statistical test that allows you to judge whether any difference between the means of two sets of data is statistically significant.
Null hypothesis: the two means are equally
Alternative hypothesis: 1) mean 1 > mean 2
2) mean1 < mean 2
3) mean 1 is not equal to mean 2
if the value in the table is greater than your t test value accept the null hypothesis.

Question 9

What is a spearmints rank test?

Answer 9

a statistical test that allows you to judge whether any difference between the means of the two sets of data is statistically significant.
Null Hypothesis: there is no correlation between x and y
Alternative hypothesis: 1) there is some correlation between x and y
2) a positive correlation between x and y (1 =perfect positive)
3) a negative correlation between x and y (-1 = perfect negative)
if the value in the table is greater than your rs value accept the null hypothesis.

Question 10

GPP?

Answer 10

gross primary productivity - the rate at which light energy is fixed by producers in photosynthesis and stored as biomass

Question 11

NPP?

Answer 11

NPP = GPP - R. the total energy fixed by photosynthesis minus the energy released from respiration. It is the energy available to be passed onto the next trophic level.

Question 12

R?

Answer 12

the rate at which glucose is broken down in respiration, providing energy for active transport, movement etc and losing energy as heat.

Question 13

Climax community?

Answer 13

a self-sustaining community with relatively constant biodiversity and species range. It is the most productive group of organism that a given environment can support long term.

Question 14

Plagioclimax?

Answer 14

a climax community that is at least in prt th result of human intervention.

Question 15

Climatic climax community?

Answer 15

the only climax community possible in a given climate.

Question 16

Succession?

Answer 16

the process by which the communities of organism colonising an area change over time.

Question 17

Primary Succession

Answer 17

1. Pioneer species such as lichens and algae penetrate rock and break it up. they trap organic material and form humus.
2. A thin layer of soil develops and plants with roots establish e.g grasses and ferns. These intermediate species die and decompose = humus layer deepens and soil has increased water and nutrients.
3. Gradually larger trees can be supported and the biodiversity of animals increases. A climax community is reached and the biodiversity is stable.

Question 18

Secondary succession.

Answer 18

Development of an ecosystem with pre-existing soil contain seeds, roots, water and nutrients. e.g after a fire, deforestation…

Question 19

Biotic Factors?

Answer 19

The living elements of a habitat that affect the ability of a group of organisms to survive there.

• predation: populations oscillate in a repeating cycle as prey and predator population increase and decrease.
• Finding a mate: the likelihood of finding a mate will detainee population size.
• Territory: territories are used to ensure a breeding pair has sufficient resources to raise young.
• Parasitism and disease: diseased animals are weakened/dead and do not reprise thus reducing population size.

Question 20

Abiotic Factors?

Answer 20

The non-living elements of the habitat of an organism.
Light: low light levels cause low biodiversity as less photosynthesis.
Temperature: in extreme temperature there will be low biodiversity. As enzymes denature etc.
Wind and water currents: hurricanes/flooding destroy organisms. Wind/currents may be needed to disperse seeds etc.
Water availability: when water stress become too serve organisms die.
Oxygen availability: when water is fast flowing/ cold there is plenty of oxygen. When soil is well aerated there is plenty of oxygen.
Soil structure and mineral content: sand has a shifting strict hence little grow. it also is drained very quickly chance minerals pass through very quickly.

Question 21

The Convention on International Trade in Endangered Species of Fauna and Flora (CITES):

Answer 21

Sites states strict rules about the trade of material from organisms. It splits organisms into three groups, in which no trade is allowed, trade with strict regulation, and organisms which are threatened in one country but not globally.
Limitations:
deals exclusively with trade agreements not the protection of ecosystems etc
Many countries have not signed up to CITES
Strong commercial interests can override scientific evidence for the need for protection.

The idea of sustainability of resources depends on effective management of the conflict between human needs and conservation. E.g conserving fish stocks or attempts to reduce causes of climate change.

Question 22

Scientific Community

Answer 22

Scientific journals: scientific findings are not widely accepted by the scientific community unless they are published in a journal. It is an easy and clear way to show scientific findings.
Peer review process: the process by which scientific papers are sent to other scientists who are experts in the field, for them to read and assess before publication in a journal.
Conferences: scientists share data, discuss ideas and listen to a number of presentations on the same area of work. Allow scientists to take a critical look at other work in their field, and collaborate together.