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HSC challenge questions!

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InnererSchweinehund:

--- Quote from: neverknow on June 03, 2019, 11:31:29 pm ---Hey, the part where it says "The patient is feeling better, but this is most likely not due to the action of the prescribed antibiotics" --> Would it be ok to call the antibiotic a placebo. Idk if it is appropriate for the context.

Thanks.

--- End quote ---

Hey!

I wouldn't call the antibiotics placebo because that gives the impression that you are saying that antibiotics are prescribed for the psychological benefit to the patient, rather than for any physiological effect ( and this impression might not sit well with an examiner).
In this case, the antibiotic would work if the disease was caused by a bacteria, but as it was caused by a virus, it is ineffective.
The patient is more than likely feeling better, not due to the antibiotic, but because of the stage of the virus and the immune system's response.
 8)

stella_atarnotes:

--- Quote from: neverknow on June 03, 2019, 11:31:29 pm ---Hey, the part where it says "The patient is feeling better, but this is most likely not due to the action of the prescribed antibiotics" --> Would it be ok to call the antibiotic a placebo. Idk if it is appropriate for the context.
AND
for this part, "gut bacteria exist in a balance with the body" --> can we just say - gut flora (microbiota) exists in a balance...

Thanks.

--- End quote ---

What InnererSchweinehund mentioned about the antibiotics is spot on. It's not very accurate to relate the antibiotics to any psychological impact since this was not the point of the prescription.

You probably won't be marked down by calling it gut flora, but just be aware that this includes all microorganisms, not just bacteria. So if you go on to say things like "antibiotics destroys gut flora" this would be an incorrect statement since microorganisms such as protists or viruses won't actually be destroyed.

elena.newlyn:
Could you please give an answer to the Medelian ration question

stella_atarnotes:
Here's the answer to last weeks question "Explain why sex-linked conditions such as red-green colour blindness do not display Mendelian ratios." Its always good to give the question a go even if your unsure if your answer is correct, hope to see some responses next week!

Things to include in your response:
- Human females have 2 copies of the X chromosome, while males have one X and one Y, the latter being much smaller and carrying very few genes.
- Males have only one copy of X chromosome genes, all which are expressed in the phenotype.
- For X-linked recessive traits such as colourblindness, this means that a male only needs to inherit a single copy of the associated allele to be affected (hemizygous).
- Meanwhile females would need to inherit two copies of the same allele to be colourblind (homozygous recessive), to prevent the recessive alleles masked by a dominant allele. - As a result, X-linked recessive traits are more common in the male population.
- Therefore, genes carried on the sex chromosome do not display Mendelian ratios because such ratios are generally only present for traits where two copies of the genes are present for both sexes.

Onto the next question!

The attached pedigree is hereditary and not sex-linked. The pedigree represents a family in which some members have a disease. Explain why it is difficult to determine whether the disease is dominant or recessive. (4 marks)

Kombmail:
The pedigree given shows an affected female and unaffected male in generation two. Since only the female is affected here , it could have been stated for a sex linked but it stated not it the question. The possible genotypes here are either rr and Rr or rr and RR. If rr and RR generations two and three should have shown evidence of this through the diagram however this is not true. This cancels out the homozygous dominant mother and homozygous recessive father option. Rr and rr is now a possibility with fifty percent offspring being homozygous recessive and fifty percent heterozygous to the disease. However second generation couple affected female and non affected male produce 100 percent affected offspring. It now becomes difficult to determine the link as the children according to the pedigree diagram must be fifty percent affected and fifty percent unaffected.

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