BIOL4 Biology Unit 4 Exam - 13th June 2011

Are there more than 3 papers?
I can only find three (June 10, Jan 11 and the Specimen)!!
If anybody has more let me know. Thanks!!

When predators eat their prey, it reduces the size of the prey population.
The predators are therefore in more intraspecific competition with each other for the fewer prey that are left.
As a result, the predator population becomes reduced as some predators aren't able to obtain prey for survival.
With fewer predators left, fewer prey are eaten; the prey population in turn increases.
With more prey available, there is therefore more food - so the predator population increases again.

Yep. You're supposed to post a question

If you're talking bout respiration then.....

Electrons are transfered down the transport chain through various carrier molecules. each carrier molecule is at a lower energy level than the previous one, so energy is lost from the electrons at these stages. this energy is used to transport protons from the mitochondrial matrix into the intermembrane space of the mitochondria. this creates a proton gradient, so protons move back into the mitochondrial matrix through the enzyme ATP synthase. the energy gained from this is used to combine ADP and and an inorganic phosphate molecule to produce ATP.


Question: What are the two main types of selection and what do they mean?

Leeching is when are removed from soil. Nitrates then go into water courses and as the nitrates build up in the water the algae start to grow, they couldn't before because the lack of nitrates limited their growth. Due to highest nitrate concentration the algae and plants start to grow exponentially. Algae grows on the surface of the water which limits the amount of light that can penetrate through the water. Light is a limiting factor for plants and they start to die because of the lack of photosynthesis. Then saprobiotic organisms grow, these start to decompose the dead plants and use these as food source, these organisms need to respire and use the organisms, oxygen is no reduced so aerobic organisms start to die and less comp for oxygen for anaerobic organisms mean they now grow exponentially and they can decompose things more.

What are the advantages and disadvantages of intensive rearing of livestock (6 marks).

Advantages:
- More energy as lessmovement, efficient
- No predation
- Less chance of disease
- Less food needed due to controlled diet, cheaper
Disadvantages
- Antibiotic resistance
- Ethical concerns, unnatural for animal
- Reduced genetic diversity

What are the assumptions for Hardy- Weinberg (4 marks)

Advantages:
- More energy as lessmovement, efficient
- No predation
- Less chance of disease
- Less food needed due to controlled diet, cheaper
Disadvantages
- Antibiotic resistance
- Ethical concerns, unnatural for animal
- Reduced genetic diversity

What are the assumptions for Hardy- Weinberg (4 marks)

-No emigration/immigration
-No natural selection
-No gene flow
-Large population size
-No mutuations
-Random mating
Outline the stages in the carbon cycle(5 Marks)

Hey, I dont have any revision notes fo this unit yet and when i get hold of some, ill upload them right away. I do have the AQA nelson thornes text book answers for this unit as they are not in the book. They may be of some help to you!

When there is a high concentration of carbon dioxide in the atmosphere: CO2 diffuses into oceans and photosynthetic aquatic organisms use CO2 to build up their macromolecules in their bodies.
Energy is transferred to other organisms in the food chain by primary consumers feeding on the producers.
When these organisms die - decomposers, more specifically, saprobiotic microorganisms secrete enzymes onto the dead organic matter by extra cellular digestion. This breaks it down into more smaller, soluble molecules which are absorbed by the saprobionts by diffusion.
CO2 is released back into atmosphere by respiration.
If decay is prevented, shells and bones sink to bottom of ocean and form sedimentary rocks such as limestone. When these are weathered, CO2 is returned back to the atmosphere.

Describe the mark release recapture method (4 marks)

Firstly a sample is captured, the first captured organisms are marked and counted using some kind of marker, the they are released, after some time the same species of organisms are captured, counted and out of the counted how many are marked. Then a population is estimated by using the calculation total in first * total in second / number marked that are recaptured in second.

Explain the process of the light independent stage (6 marks)

Also why did this receive a downvote? Is it wrong? http://www.thestudentroom.co.uk/showpost.php?p=32007220&postcount=134

Firstly a sample is captured, the first captured organisms are marked and counted using some kind of marker, the they are released, after some time the same species of organisms are captured, counted and out of the counted how many are marked. Then a population is estimated by using the calculation total in first * total in second / number marked that are recaptured in second.

Explain the process of the light independent stage (6 marks)

Also why did this receive a downvote? Is it wrong? http://www.thestudentroom.co.uk/showpost.php?p=32007220&postcount=134

I wouldn't say the the same species of organisms are captured. It makes it seem like you are going to get the same sample from before. I would say a second sample of the same species would be taken after some time. Make sure you say that the marking doesn't make the organisms more liable for predation. I would just add it it, you never know with AQA.

1) Occurs in the stroma
2) RuBP combines with CO2 using an enzyme
3) Converts into 2 molecules of GP
4) GP is reduced to TP using reduced NADP from light dependent reaction.
5) TP is used to make useful substances and glucose
6) ATP is needed to regenerate RuBP so the cycle can repeat.

What problems does deforestation cause?

It increases the CO2 concentration in the atmosphere as it reduces photosynthesising biomass on Earth.

I cant think of anything else @.@

How would you sample buttercups on a field? (2 marks)

I wouldn't say the the same species of organisms are captured. It makes it seem like you are going to get the same sample from before. I would say a second sample of the same species would be taken after some time. Make sure you say that the marking doesn't make the organisms more liable for predation. I would just add it it, you never know with AQA.

1) Occurs in the stroma
2) RuBP combines with CO2 using an enzyme
3) Converts into 2 molecules of GP
4) GP is reduced to TP using reduced NADP from light dependent reaction.
5) TP is used to make useful substances and glucose
6) ATP is needed to regenerate RuBP so the cycle can repeat.

What problems does deforestation cause?

How about habitats being destroyed? .....species diversity?

yeah, like niches and habitats?

forgot about those!
lol