lots of questions of various topics........

[scholesmu]

i am unsure about these questions, please help, thanks

1. under light microscope, structures are seen more clearly in stained cell than unstained cell,becasue
a)many cytoplasmic structures are colourless and can't be distinguished
b)staining improves the resolving power of microscope
c)cells are always killed by stains and this stops any moverment
d)additon of heavy metals such as lead essential for visualization


2.In a small lump of soil, a fragment of organic matter is surrounded by mineral particle. The centreof organic matter is anerobic. The biological activity is
a)due to presence of group of chemosynthetic bacteria
b)due to actvitiy of bacteria and fungi by extracellular digestion
c)assiocated with diffusion of nutrients from digestion from the outside of the organic fragment

3.The reason of C4 plants tend to more successful than C3 plants in hot and dry areas because:
can this be the explaination!?
C4 plants have Co2-fixing exzyme with higher affinity of Co2 than that of C3 plants, allowing them to photosynthesize efficiently with their stomata partly closed


4.Two microbes have been grown together in single agar plate.The first microbe has suppress the growth of the second microbe. The first microbe is producing a seconding metabolite, which is,
a)unsafe to humans and most of the others organisms
b)unsafe to unknown range of organisms
c)safe to humans becasue it has only been tested against one other microbe
d)unsafe to humans becasue the growth conditions determined the rate and concentration of toxin and thay are equivlent to those in human digestive system

[canalon]

What do YOU think? You have problems, what are they? We will not answer the question for you. but we might help you find the right answers.
Do what you do for 3 (I have no idea,I hate plants) for the others.

[scholesmu]

yes
for question 1, i have no idea
staining make the cell more distinct,isn't it?but what is the actual thoery behind this?

question 2 i think the answer is either a or b

question 4, i only know that second metablites are something that inhibit the growth of surrounding organisms....so is it/ what is actually do with humans? i have no idea on this

[canalon]

1/There are many different stains, that have more or less specificity, w/r to what they are reacting with, but basically, the idea is to increase contrast between stained and non stained structure. Some stains are called vital and do not kill a cell, while other do.

4/Well in this case the point is what do you know from the data you have at hand? We know that the secondary metabolite is inhibiting the growth of another bacteria and that is about it. So the answer must take that into account and there is only one answer that do not extrapolate on the information you have...