Chapter 23 Ecosystems Flashcards

Question

Why do CO2 levels fluctuate naturally?

Answer 1

At night photosynthesis stops, but respiration of plants continues, so increases CO2 levels In winters, days are shorter, so less photosynthesis

Answer 2

Combustion of Fossil Fuels Deforestation, and potentially combustion of trees Ocean Acidification Leads to global warming, melting of ice caps, flooding, extreme weather

Answer 3

Succession- a process in which ecosystems change Primary: New land, no soil or organic matter present e.g from igneous rock, sand dunes Secondary: Soil remains, but no plants or animals remain, e.g land post forest fire

Answer 4

Barren land- Pioneer Species Intermediate community- secondary and tertiary colonisers, leading to shrubs and small trees Climax Community

Answer 5

Lichens First Seral Stage, adapted to barren land Specially adapted to survive: - produce a large quantity of seeds/spores - seeds germinate rapidly - tolerance to extreme environments -fix nitrogen and can photosynthesise When they die, increase the humus (organic component) of the soil so other species can survive

Answer 6

Secondary colonisers: Mosses - able to survive since some humus of the soil, and presence of nitrates, and some water retention - arrived as seeds Tertiary colonisers: Ferns --- Grasses --- Shrubs --- Small Trees At each seral stage, the rock is eroded more, increased humus, increased water retention Better adapted plants outcompete members at the previous seral stage, less specific adaptations

Answer 7

A stable state with a few dominant species Lower biodiversity than End of primary succession

Answer 8

After plants arrive Insect/Worms from neighbouring areas ---- secondary ---- tertiary Slower than plants

Answer 9

Succession halted by humans/ artificially with the new community called a plagioclimax e.g via trampling of vegetation by domesticated animals, or burning

Answer 10

Distribution- Locations of organisms within an ecosystem, likely to not be random Abundance- The number of organisms

Answer 11

Line Transect- Line, sample at regular intervals Belt- Two parallel lines, sample space in between at regular intervals Useful for measuring how changes

Answer 12

Immigration and births increase abundance Emigration and deaths decrease abundance

Answer 13

Cheap and quick to run But unlikely to be representative if the sample size is small

Answer 14

(Number of individuals in a sample) / (sample area) Organisms per m2

Answer 15

Sample- mark, release Sample later, same area, same technique Size= (first sample x second sample) / second which were marked Doesn't take into account emigration/immigration Needs a large sample size to be accurate

Answer 16

D = 1- sum of (n/N)^2

Answer 17

Nitrogen fixation Denitrification

Answer 18

Lay tape measures from the starting area Place a quadrat between the tapes Identify the species and count the number of them, record. Repeat at regular intervals

Answer 19

Constructed dams- Reduce flow rate to make slow water a new habitat Felled trees- gives sunlight to lower levels, prevent climax community Lodges- sheltered habitats for insects Also promotes ecotourism

Answer 20

Fallen trees could cause damage to river beds, but areas likely to not be full of business Dams could promote flooding so loss of farmland. Depends on severity of flooding.

Answer 21

Woods KJ/M^-2Yr^-1 Ocean KJ/M^-3 Yr^-1

Answer 22

Ans/ (/1000/1000) 1/ 1x10^-6

Answer 23

Reduce space for movement so reduce energy for muscle contraction/respiration Keep warm to reduce energy for thermoregulation High protein/energy diets Vaccinations Use selective breeding/ genetic engineering to provide genes to maximise growth

Answer 24

Acidic conditions mean decomposers cannot survive Denatures enzymes and lack of oxygen So decomposition does not take place

Answer 25

Take a sample of the producers, either measure dry mass or use calorimetry (burn in oxygen) to measure energy change via temperature change of the water heated Scale up to calculate energy change of the population Repeat for a sample of the primary consumers and scale Efficiency= (energy consumers / energy producers) x 100

Answer 26

Different temperatures, light intensities- greater rate of photosynthesis in some places which can be transferred into more biomass Less limiting for space Other factors such as lower humidities, species produce less waste

Answer 27

Position within the food chain Primary consumers the best, they are herbivores As they become carnivorous, even if more biomass at that stage is transferred, too much is lost between the stages to be efficient