# Biology unit 4 question watch

1. http://files.physicsandmathstutor.co...%20A-level.pdf

Can someone explain question 8a and 8b please
2. 8a - Think about the process of decomposition. The bacteria are digesting the organic matter so that they can absorb it as food - which process would be involved in digestion?

8bi - Look at the third sentence "Every few weeks, one pile of each type of leaf was removed and weighed.". What would happen if you only used 1 pile?

8bii - You need to look at the evidence for each conclusion. For the first one, look at which kind of leaf decomposed faster - your answer to iii might help here. Conclusion 2 - does the student actually have any data to prove this? Conclusion 3 - this just states that as time changes, mass will change. You can see from the table that it does indeed.

8biii - Think about the substances produced in decomposition and digestion. Proteins and carbohydrates are broken down into soluble sugars and amino acids - what will happen to these when they come into contact with the wet ground? The bacteria will also be respiring - what happens to the products here? There will also be larger organisms that can move around freely that may enter and exit the buckets. How will this affect mass?

8biv - How does a more temperature affect the rate of respiration? Enzyme action? Bacterial colony growth? Remember to explain the effects on enzymes in terms of enzyme-substrate complexes, as always! You could also discuss what would happen if the temperature was raised too high, but I'm not sure if that's what they're looking for here.
3. (Original post by lizardlizard)

8bi - Look at the third sentence "Every few weeks, one pile of each type of leaf was removed and weighed.". What would happen if you only used 1 pile?
for 8bi: i am thinking if the independent variable is number of weeks, dependent variable is mass, then we can plot a graph using data from one pile of each type. So why the answer is not to calculate a mean?
4. (Original post by alesha98)
for 8bi: i am thinking if the independent variable is number of weeks, dependent variable is mass, then we can plot a graph using data from one pile of each type. So why the answer is not to calculate a mean?
We can't calculate a valid mean from them, as each pile is tested at a different time. Think about what would happen if we only had 1 pile - since 1 pile is used up to make 1 measurement, how would we test 5 times? If there was only 1 pile, we would only make 1 reading and so we would not obtain the needed range of results.
5. (Original post by lizardlizard)
We can't calculate a valid mean from them, as each pile is tested at a different time. Think about what would happen if we only had 1 pile - since 1 pile is used up to make 1 measurement, how would we test 5 times? If there was only 1 pile, we would only make 1 reading and so we would not obtain the needed range of results.
ok, I think I know where i have got wrong. So if a person remove the leave from the ground and measure the mass in week 4, the leaves need to be replaced in order to continue to get a mass for week 8. Therefore 5 piles are needed to get a range of data for the independent variable because the question does not say that the leaves would be replaced after measuring the mass?
6. Read the question carefully - "one pile of each type of leaf was removed and weighed". This means that every time, a whole pile was removed, so you can't use that pile again.

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