BIOL4 Biology Unit 4 Exam - 13th June 2011

Reply 660

Jing_jing

14

Original post by FatalError

What is the enzyme that fixes CO2 into the calvin cycle?

Rubisco, which has 8 active sites! Just a fun fact there :biggrin:

Also thought to be the most abundant enzyme in the world.

Reply 661

Rickesh

What is the difference between agricultural and natural ecosystems?

Reply 662

FatalError

Ping pong answers are good because in January i remember 4 questions come up that people asked here. I still failed though, HSW messed me up!

Reply 663

Rickesh

Original post by FatalError

Ping pong answers are good because in January i remember 4 questions come up that people asked here. I still failed though, HSW messed me up!

What did you get?

Reply 664

Master.K

18

What on conservation could come up, there's barely anything in the nelson thornes book on it. :s-smilie:

Reply 665

FatalError

Agricultural ecosystems have additional energy input in the form of fossil fuels for farming machinary and food for farmers themselves. Increase in productivity due to preventing limiting factors with the use use of additional nitrogen fertilizer. Reduced species diversity due to use of pesticides to control pest numbers and also plagioclimax so succession doesn't occur.

Reply 666

FatalError

I got an E. I had C3 in the morning, Business Unit 3 straight after, 30 minutes break then Biology!

Reply 667

Rickesh

Original post by FatalError

Agricultural ecosystems have additional energy input in the form of fossil fuels for farming machinary and food for farmers themselves. Increase in productivity due to preventing limiting factors with the use use of additional nitrogen fertilizer. Reduced species diversity due to use of pesticides to control pest numbers and also plagioclimax so succession doesn't occur.

yep..your turn

Reply 668

FatalError

What on conservation could come up, there's barely anything in the nelson thornes book on it.

Just remember the types of land.

Moorland- Basically succession prevented by burning and only heather survives (it's a plant species)
Hedgerows- Just cutting so doesn't develop into forest.
Grassland- Grazing. Remember that grass can still grow but not other plant species because grazing cuts their shoots off whereas grass auxin is produced at the base so it can still grow despite grazing.

Reply 669

Black Butler

Hi what are definitions for :

gross productivity and net productivity.

Note : I know what they are just want a typical aqa answer.

Reply 670

FatalError

Why are hedgerows a disadvantage to farmers?

Reply 671

FatalError

gross productivity and net productivity.

Ermm, is gross productivity the amount of energy initially available and net productivity the amount of energy left over at the trophic level after respiratory losses?

Reply 672

Abby :)

8

Original post by FatalError

Why are hedgerows a disadvantage to farmers?

Takes up space that could be crops
Makes turning machinery difficult
Acts as habitats for pests.

Reply 673

Jing_jing

14

Original post by Black Butler

Hi what are definitions for :

gross productivity and net productivity.

Note : I know what they are just want a typical aqa answer.

Gross productivity is the total amount of organic material produced whereas net productivity is the total increase in dry biomass after respiratory losses?

I'm always a bit fuzzy on those two... and the majority of ecology :tongue:

Reply 674

Rickesh

Original post by FatalError

Why are hedgerows a disadvantage to farmers?

Because they reduce crop yield, as the crops have competition (interspecific) e.g for nutrients such as nitrate ions this becomes the limiting factor and prevents photosynthesis from reaching its maximium. They also take up a lot of space therefore less space fpr the crops.

Reply 675

FatalError

Takes up space that could be crops
Makes turning machinery difficult
Acts as habitats for pests.

Yep that's it. Also remember that plant species in hedgerows will compete for nutrients and water in the soil and so could reduce crop productivity.

Reply 676

Black Butler

Original post by Jing_jing

Gross productivity is the total amount of organic material produced whereas net productivity is the total increase in dry biomass after respiratory losses?

I'm always a bit fuzzy on those two... and the majority of ecology :tongue:

Ive got it as the rate at which chemical energy (from biomass) is assimilated by the plant

and for net productivity the same thing except an extra 'excluding respiratory losses'

eh?

Reply 677

Jing_jing

14

Original post by Black Butler

Ive got it as the rate at which chemical energy (from biomass) is assimilated by the plant

and for net productivity the same thing except an extra 'excluding respiratory losses'

eh?