energy flow

Question 1

define autotroph

Answer 1

an autotroph is an organism that creates its own energy from sunlight or from chemical reactions

Question 2

define heterotroph

Answer 2

a heterotroph is an organism that cannot produce its own food (eats plant or animal material)

Question 3

define food chain

Answer 3

sequence of organisms through which energy and nutrients move in a community

Question 4

define food web

Answer 4

system of interlocking, interdependent food chains

Question 5

define trophic level

Answer 5

hierarchal levels in ecosystem (producers, primary consumers, secondary consumers, decomposers)

Question 6

define decomposer

Answer 6

decomposers are organisms that eat dead organic matter and transform them into inorganic molecules

Question 7

define detritus

Answer 7

dead biomass

Question 8

define detritivore

Answer 8

decomposers

Question 9

define compensation point

Answer 9

when photosynthesis equals respiration

Question 10

define consumer (primary and secondary)

Answer 10

primary consumers are herbivores and secondary consumers are carnivores

Question 11

define primary productivity

Answer 11

primary productivity is the creation is new organic matter -> change in biomass per unit time by primary producers (synthesis of CO2)

Question 12

define net primary productivity

Answer 12

net primary productivity is primary productivity after the cost of plant respiration
- amount of stored chemical energy (biomass) per unit time
- net flux of carbon from atmosphere into green plants per unit of time

Question 13

define biological amplification/magnification

Answer 13

biological amplification: toxins accumulate over lifetime
biological magnification: toxin levels increase up the food chain with higher trophic levels

Question 14

describe photosynthesis (inputs + outputs and where it occurs)

Answer 14

photosynthesis occurs in chlorophyll which is a pigment in chloroplast which is an organelle in plant cell in green tissue of plant
- inputs: CO2 + H20 + light energy
- outputs : O2 + glucose

Question 15

what are inputs and outputs of respiration?

Answer 15

inputs: O2 + glucose
outputs: CO2 +H20 + energy

Question 16

how is productivity measured?

Answer 16

• by measuring amount of biomass fixed
• by measuring carbon dioxide concentrations

Question 17

why is there less energy available at the top of a food chain than at the bottom?

Answer 17

because of energy transfer inefficiencies, only 10% of energy is passed on from one trophic level to another (energy is lost from respiration and excretion + not all biomass is consumed)

Question 18

why do some say that the Earth can support less carnivores than herbivores?

Answer 18

because less energy is needed for herbivores (due to energy transfer efficiency), more biomass is needed to support carnivores

Question 19

consider two food chains of unequal length, both start with plants containing equal amounts of pesticide DDT. At the top of which food chain would you expect to find higher levels of DDT: the shorter or longer? why?

Answer 19

the longer because DDT biomagnifies so the more trophic levels there are, the more DDT has potential of accumulating

Question 20

can you rank biomes in terms of their NPP?

Answer 20

highest to lowest:
1. tropical rainforest
2. temperate deciduous forest
3. boreal forest
4. grassland
5. tundra
6. desert

Question 21

can you describe the global cycle of carbon including the major sinks and sources?

Answer 21

carbon from atmosphere can go into plants for photosynthesis (sink)
-> from photosynthesis, live plants will respire which will bring back some CO2 into atmosphere
-> dead plants will decompose and decomposers will release more CO2 into atmosphere from respiration (source)
-> some dead plant material will not decompose fully and turn into fossil fuels (sink)
-> some carbon will store in soil after decomposition (sink)
-> animals will eat plants and fix glucose and emit CO2 as they respire (source)
-> cement production, volcanoes and burning of fossil fuels emits CO2 (source)
-> long term sinks are swamps and marshes because decomposition is slow

Question 22

can you explain the recent increase of carbon dioxide in our atmosphere and greenhouse warming?

Answer 22

• recent increase of carbon dioxide is from burning of fossil fuels and cement production (carbonate rocks)
• greenhouse gases have the ability to stop longwave radiation from leaving the atmosphere, keeps it within the stratosphere and warms the planet

Question 23

Why is the Mauna Loa CO2 curve not a smooth line?

Answer 23

the curve is not smooth because there are seasonal fluctuations in CO2 emissions. When the Northern Hemisphere is in summer, CO2 is taken up by plants because there is more photosynthesis occuring. In winter, when many plants are dormant, respiration is the dominant process so more CO2 is emitted.

Question 24

what is a stoma?

Answer 24

pore at surface of leaf
- opens and closes thanks to guard cells (swollen with water = open), when open, CO2 enters intercellular chamber -> with help of water vapor, CO2 goes through cell wall

Question 25

what controls the amount of carbon in the atmosphere?

Answer 25

• geological storage compartments (fossil fuels, carbonate rocks, volcanoes)
• burning wood and other plant matter
• respiration from biosphere