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Murljashka [212]
3 years ago
13

Cyanobacteria are important to the evolution and advancements of other life on earth because they

Biology
1 answer:
kompoz [17]3 years ago
3 0

Answer:

Cyanobacteria are microscopic organisms found in all kinds of water. They are single-celled organisms and produce their own food from sunlight via photosynthesis. Cyanobacteria are important to evolution because they developed the oxygen atmosphere we live in by producing waste from cyanobacteria. Plants also evolved from Cyanobacteria.

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2. List three sources of error that could account for the differences between your values for the enthalpy of fusion of water an
Dvinal [7]

1 trial :  nothing is given for result comparision - so we have no idea if it's a mistake.

2nd trial : The results can be compared - if varies, one may go wrong, but which one?

3rd trial : If 3rd result is different from 1st and 2nd, it is unreliable.

calculating enthalpy of fusion. M, C and m,c = mass and specific heat of calorimeter and water, n, L = mass and heat of fusion of ice; T = temperature fall.

L = (mc+MC)T/n.

c=4.18 J/gK. assuming copper calorimeter , so C=0.385 J/gK.

1. M = 409g, m = 45g. T = 22c, n = 14g

L = (45*4.18+409*0.385)*22/14 = 543.0 J/g.

2. M = 409g, m = 49g, T = 20c, n = 13g

L = (49*4.18+409*0.385)*20/13 = 557.4 J/g.

3. M = 409g, m = 54g, T = 20c, n = 14g

L = (54*4.18+409*0.385)*20/14 = 547.4 J/g.

(i) Estimate error in L from spread of 3 results.

Average L = 549.3 J/g.

squared differences average (variance) = (6.236^2+8.095^2+1.859^2)/3 = 35.96

standard deviation = 5.9964

standard error = SD/(N-1) = 5.9964/2 = 3 J/g approx.

% error = 3/547 x 100% = 0.5%.

(ii) Estimate error in L from accuracy of measurements:

error in masses = +/-0.5g

error in T = +/-0.5c

For Trial 3

M = 409g, error = 0.5g

m = 463-409, error = sqrt(0.5^2+0.5^2) = 0.5*sqrt(2)

n =(516-463)-(448-409)=14, error = 0.5*sqrt(4) = 1.0g

K = (mc+MC)=383, error = sqrt[2*(0.5*4.18)^2+(0.5*0.385)^2] = 2.962

L = K*T/n

% errors are

K: 3/383 x 100% = 0.77

T: 0.5/20 x 100% = 2.5

n: 1.0/14 x 100% = 7.14

% errors in K and T are << error in n, so ignore them.

% error in L = same as in n = 7% x 547.4 = 40

The result is (i) L= 549 +/- 3 J/g or (ii) L = 550 +/- 40 J/g.

Both are very far above  334 J/g, so there is at least one systematic error  

e.g: calorimeter may not be copper, so C is not 0.385 J/gK. (If it was polystyrene, which absorbs/ transmits little heat, the effective value of C would be very low, reducing L.)

Using +/- 40 is best.

However, the spread in the actual results is much smaller

* measurements were "fiddled" to get better results; other Trials were made but only best 3 were chosen.

<h3>Other sources of error: </h3>

L=(mc+MC)T/n is too high, so n (ice melted) may be too small, or T (temp fall) too high - why?

* we have assumed initial and final temperature of ice was 0c, it may actually have been colder, so less ice would melt -which explain small values of n

* some water might have been left in container when unmelted ice was weighed (eg clinging to ice) - again this could explain small n;

* poor insulation - heat gained from surroundings, melting more ice, increasing n - but this would reduce measured L below 334 J/g not increase it.

* calorimeter still cold from last trial when next one started, not given time to reach same temperature as water - this would reduce n.

3 0
3 years ago
Energy is stored in the body primarily as __________ in the muscles and liver and as ___________ in subcutaneous body fat.
svetoff [14.1K]

Answer: Energy is stored in the body primarily as GLYCOGEN in the muscles and liver and as TRIGLYCERIDE in subcutaneous body fat.

Explanation:

We take in food for the purpose of ENERGY, building of worn out tissues of the body and to boost the body immunity. After the intake of food, amino acids from dietary protein are used to synthesize body proteins and other molecules, carbohydrate is used to maintain blood glucose and to build glycogen stores, fat is used for energy or stored in the body.

The body must have a steady supply of energy with some of it coming from the metabolism of glucose.

GLYCOGEN formation occurs when there is excess blood glucose level in the process called glycogenesis. It is the suitable way glucose can be stored as it is insoluble and can not disturb the osmotic pressure of the cells. When food is restricted over time, glycogen stores are expended, and the body must rely on the breakdown of stored GLYCOGEN to be converted to glucose for energy production.

Also, energy for tissues that don't require glucose can come from the breakdown of triglycerides in the adipose tissue. TRIGLYCERIDES are formed by the liver when excess calories are taken, and are stored in the adipose tissues.

4 0
3 years ago
A period in a man’s life, usually during his 70s or 80s, when testosterone decreases, causing a decrease in spermatogenesis, is
kolezko [41]
Answer: Andropause
I hope it helps
6 0
3 years ago
E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA
White raven [17]

Answer:

Option (d).

Explanation:

DNA is the genetic material of all the organism except some viruses. DNA is composed of nitrogenous base, deoxyribose pentose sugar and the phosphate group.

DNA replicatese by semi-conservative mode of replication in which one the daughter DNA consists of one newly synthesized strand and one parental strand. This mode of replication was explained by Messelson and Sthal experiment. The cells from 15N medium are transferred to 14N medium the band of intermediate density was observed. The daughter DNA consists of one 15N DNA strand and one 14N DNA strnd. This strand undergo replication in the 14N medium. This time one low density DNA band ( contains 14N - 14N DNA strand) and one intermediate density band ( 14N-15N DNA).

Thus, the correct answer is option (d).

8 0
3 years ago
These superior inherited traits led Darwin to another idea, the finches' increased
lesya [120]

Answer:

legth of life is the answer

8 0
2 years ago
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