f

1. Because chromosomes comes in pairs.

2. As the number of chromosome grows, the animals become bigger and more “complex”. More chromosomes are needed as the animals become more complex because of the way they behave and live.

But  a dog has more chromosomes than an american black bear. So the number of chromosome may not be a reliable source for depicting whether or not the organism is more complex than another organism.

3. Because chromosomes may divide or fuse, depending on the cycle that they are in.

4. The chromosomes in chimpanzee’s decreased for a change in the number of chromosomes during human evolution.

1. I –  Cell wall

II – Cytoplasm

III- Plasma membrane

IV – Nuclear membrane

V – Nucleus

VI – Nucleolus

VII- Chloroplast membrane

VIII- Thylakoid

IX- ribosome

X

XI – Starch grain

2a) Magnification = size of image/ actual size of specimen

21000 =  30mm/actual size

Actual size = 30/21000

Actual size = 0.0014mm

2b) the total length of the chloroplast is 8.3cm in image, to calculate the real length, it’s the following :

Magnification = size of image/ actual size of specimen

21000 = 83mm/Actual size of specimen

Actual size = 83/21000

Actual size = 0.0040mm

Therefore it is an estimation of around 0.0040mm.

3.  It is in the light because this is taken by a electron microscope, we can assume that it is photosynthesizing as starch grain is presented.

4. lysosomes, golgi and mitochondria.

1)

The pH was monitored during this experiment to show the change in carbon dioxide concentration . Carbon dioxide is an acid, so it uses it, it produces oxygen, the pH of the water will thus increases (because it becomes less acidic).

2)

-The independent variable is temperature

-dependent variable is the pH.

3)

-Time should go on the x-asis 

-pH should go on the y-axis.

4)

The optimum temperature for photosynthesis in the green alga Chlorella is the temperature at which the change in pH is the greatest. Therefore, the optimum temperature is around 25.0˚C because the change in pH was greatest.

However, when taking the ±0.05 uncertainty into consideration, the actual optimum temperature could be different. In conclusion, the temperature is around 25.0˚C.

5)

Different alga has different optimum temperature for photosynthesis as they are different.

6)

The experiment controls the initial CO2 concentration and the temperature, which is good, however, the experiment doesn’t control the light intensity and the concentration of the alga which could affect the pH. Therefore, a certain light intensity and a certain alga concentration should be the same for all trials.

1)

a) I t is necessary for boiling and then cooling the water before the experiment as it removes the carbon dioxide and other dissolved gasses so that the concentration of carbon dioxide can be controlled.

b) Keeping the water at 25 degrees and brightly illuminated is necessary because the temperature affects the rate of photosynthesis because as the light intensity increases, the consumption of carbon dioxide will also increase.

c) Repeating bubble counts until several consistent counts have been obtained is necessary because this ensures that if there are any anomalies, they would be identified.

2)

Another factor that could be investigated using bubble counts with pondweed is the effect of temperature on the rate of photosynthesis. We could change the temperature instead of changing the concentration of carbon dioxide.

3)

We could measure the rate of oxygen production more accurate by carrying more trials (5 trials) then finding the average of the five bubble counts. Another way is using distilled water from the beginning in order to lessen the trouble in extracting the dissolved gases.