• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

biology paper 1 doubts

Messages
57
Reaction score
11
Points
18
i
I don't get how to do this.
Please help.
Thanks..
it has been stated from the question, that the net productivity of the producer is 1.8%.
but the actual energy the herbivore [primary consumer] receive is only 0.75%.
therefore, the proportion is 0.75/1.8, the ratio of energy received to energy sent.
 
Messages
274
Reaction score
277
Points
53
Nov 09. ques 13
Please explain why the answer is A and not C?
thanks..
Every single order of protein structure affects the shape of a protein (including the active site of an enzyme).

Take it this way: with sickle cell anemia, one of the polar amino acids is replaced by a non-polar one. This changed the primary structure. Since the new amino acid is non polar, it can't make any hydrogen bonds, so the secondary structure is ruined. Also, since the new amino acid is non polar, it has to face the centre of the molecule, not outside, so the polypeptide has to refold to do that - tertiary structure ruined. Now the entire beta polypeptide chain cannot interact with the other three in the same way anymore - quaternary structure changed.
 
Messages
65
Reaction score
25
Points
28
Each of the following events takes place during mitosis.
1 centromeres divide
2 chromatids move to opposite poles of the cell
3 chromosomes line up along the equator of the spindle
4 chromosomes uncoil
5 two chromatids are joined by a centromere
In which order do the events take place?
first to last

A
1 2 4 5 3
B 3 1 2 4 5
C 4 5 3 1 2
D
5 3 1 2 4
can someone please help me,,, why is the answer D not C ???
 
Messages
175
Reaction score
45
Points
28
Every single order of protein structure affects the shape of a protein (including the active site of an enzyme).

Take it this way: with sickle cell anemia, one of the polar amino acids is replaced by a non-polar one. This changed the primary structure. Since the new amino acid is non polar, it can't make any hydrogen bonds, so the secondary structure is ruined. Also, since the new amino acid is non polar, it has to face the centre of the molecule, not outside, so the polypeptide has to refold to do that - tertiary structure ruined. Now the entire beta polypeptide chain cannot interact with the other three in the same way anymore - quaternary structure changed.
Thankyou so much! Great explanation!
 
Messages
65
Reaction score
25
Points
28
Each of the following events takes place during mitosis.
1 centromeres divide
2 chromatids move to opposite poles of the cell
3 chromosomes line up along the equator of the spindle
4 chromosomes uncoil
5 two chromatids are joined by a centromere
In which order do the events take place?
first to last

A
1 2 4 5 3
B 3 1 2 4 5
C 4 5 3 1 2
D
5 3 1 2 4
can someone please help me,,, why is the answer D not C ???
sorry i can type it again if its confusing
 
Messages
197
Reaction score
423
Points
73
To find the greatest change in % saturation of Hb, move 1 small square to the right along the x-axis, and see the corresponding change on y-axis. This change is greatest where the graph is steepest, in the B region.
Mercii :)
 
Messages
274
Reaction score
277
Points
53
sorry i can type it again if its confusing
During prophase, the chromosomes coil and condense, and they don't uncoil until the end of telophase.
In prophase, the two chromatids are still held together by a centromere (5). After that, metaphase pulls all the chromosomes to the metaphase plate (imaginary line drawn through the perpendicular bisector of the centrioles) (3). In the beginning of anaphase, the spindle fibres break the centromere (1) and pull each chromatid to the opposite pole of the cell (2). As mentioned near the end, the chromosomes uncoil after telophase (4) which is followed by cytokinesis.
 
Messages
65
Reaction score
25
Points
28
During prophase, the chromosomes coil and condense, and they don't uncoil until the end of telophase.
In prophase, the two chromatids are still held together by a centromere (5). After that, metaphase pulls all the chromosomes to the metaphase plate (imaginary line drawn through the perpendicular bisector of the centrioles) (3). In the beginning of anaphase, the spindle fibres break the centromere (1) and pull each chromatid to the opposite pole of the cell (2). As mentioned near the end, the chromosomes uncoil after telophase (4) which is followed by cytokinesis.
thank u sooooo much !!! i finally get it =)
 
Messages
142
Reaction score
131
Points
43
I don't get how to do this.
Please help.
Thanks..
Walaikum salaam! The question asks for the proportion of net productivity passing on from the producers to the primary consumers.
Hence you can ignore the 4.0% from the producer as it represents the gross productivity. Likewise, the 2.3 % is irrelevant .The value of the net productivity passing from producers to primary consumers is 0.75%.
Moreover, 1.8% is the total energy passing from the producers. So the proportion is 0.75/1.8.
You can think of the net productivity as the effective or net energy transfer and the gross productivity as the total amount of energy passing from one trophic level to the next.
Hope I helped! ;)
 
Messages
274
Reaction score
277
Points
53
Yes, you're right. A habitat is where an organism lives. But if the tree carries out phtotosynthesis and absorbs water etc..., then it is more than "just a habitat". They're describing for you the role of the tree in the ecosystem which is its niche. ONE of its roles may be that it is a habitat, but that's not all. Makes sense?
 
Top