17

Your reasoning is sound and correct. The answer key is wrong. An unclotted blood sample needs something to prevent clotting. Extracellular calcium is required for both the coagulation cascade and platelet activation. It even has its own name in this context, Factor IV. This why EDTA, a calcium chelator, is used in some blood collection tubes to delay ...


8

There is no answer to your question The doubling time of a bacterium is dependent on the conditions: primarily on the temperature and the availability of nutrients, but other factors can apply. Because of this, the doubling time of any particular bacterial strain cannot be considered in the abstract, thus to give a single number we can consider the optimum ...


5

I think the question's phrasing is arguably a little wobbly, typically as to the nature of what someone would mean by the term "reptile". But I think you understood what your teacher was expecting. I agree with you, answer is B. Reptilia is a clade (clade = monophyletic group) that encompasses all species that we traditionally classify as reptiles + all ...


3

TL;DR No, it won't die. Lizards/snakes are usually immune to their own venom. Since I couldn't find a good answer to this recurring question on this site, I will try to summarize it here. I found more research on snakes than on lizards, but for now we will just assume that similar mechanisms can be found in lizards. First, the question is how the venom ...


2

Welcome to Biology.SE! I think you've come to a reasonable conclusion, but not for exactly the right reasons. The genomes of several strains of Escherichia coli have been sequenced (e.g. https://www.ncbi.nlm.nih.gov/nuccore/U00096) so you could predict the sizes of the fragments you would expect from your digest. The genome size of E. coli is about 4.6 ...


2

The individual values in the OP's onion label are not out of line with the U.S. Department of Agriculture's reference data. There are two of the latter, one for "Onions, raw" and one for "Onions, sweet, raw". Their figures would lead to expecting carbohydrates of 13.8g or 11.2g, respectively, for a 148g sample. The negative difference can be explained by ...


2

The values on the nutrition label from the question (11 g total carbs, 9 g sugars, 3 g fiber) could be actually explained by rounding: Total carbohydrates: 11.45 (rounded to 11) Sugars: 8.55 g (rounded to 9 g) Fiber: 2.55 g (rounded to 3 g) ...which would mean there are additional 0.35 grams of non-sugar, non-fiber carbohydrates... ...BUT... ...using ...


2

Hormones have antigens. Usually they are antigens our immune systems recognize as self. Pretty much any big biological molecule will have antigens. FSH is no exception. The binding of FSH to anti-FSH antibodies (in a laboratory system) is one way to measure FSH levels in a human. Definition and Measurement of Follicle Stimulating Hormone B. High-...


1

If that is the case, why would C4 plants make PEPcarboxylase the primary acceptor instead of RuBisCO? Since it is not so, C4 plants were forced to take this alternative and make RuBisCO confined only to the bundle sheath cells. The problem in C3 was photorespiration, since oxygen used to competitively inhibit the uptake of carbon dioxide by RuBisCO. Hence it ...


1

I am going to post an answer that is maybe not helpful for the exact goals, but which will maybe help restate the problem to be easier. As commenters noted it is super big and complex, many whole careers have been devoted to solving very small parts of this problem. Possible problems with premise I think that this question starts from this statement as a ...


1

It is not solution X what is going out of the cell, but the solvent (water) of solution X. Also, you need to keep in mind that the cell wall permeability is by far less selective than the cell membrane. This is why solution Y can diffuse freely to Z.


1

The article cited in the question goes on to discuss the different classes of restriction enzyme, for which the recognition ‘style’ differs. Not all recognize palindromic sequences. Type II restriction enzymes These have been divided into a number of subclasses (reviewed by Pingoud and Jeltsch). Those regarded as orthodox — which are the ones generally ...


1

The first question is poorly designed the only things with a high chance of surviving mass extinctions are organisms that occur in large numbers over a wide range of environments, without more detail neither A nor B would have a strong preference for survival compared to the other. Mass extinctions are too unpredictable, neither by itself gives you a large ...


1

You misunderstood slightly what PAM1 means; it's actually (from Wikipedia) "1 [PAM] mutation to occur per 100 amino acids". So PAMn makes sense for any n, as in the 100 amino acids may mutate more than once each, on average. Or if you put it in terms of PAM distance... Is possible for two sequences to be more than 100 PAM apart? Yes: One position can ...


1

Yes, you're correct. The question is asking for a positive sample that would be amplified by E. coli specific primers. Known E. coli DNA would do the trick.


1

At each base, you can have 4 different bases (A,T,C or G). Therefore for the first base there are 4 possibilities, namely A T C G For the first two base pairs there are $4^2 = 16$ possible combinations AA AT AC AG TA TT TC TG CA CT CC CG GA GT GC GG For the first three bases, there are $4^3$ possible combinations. For 8 base pairs, there are $4^8 = 65536$...


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