- Forums
###### Biology A-level help

Watch

10 months ago

Hi, can anyone plz help me with this biology question?

In a zoo, there are 325 guinea pigs and 52 of them have long fur which are recessive. Using the Hardy-weinberg principle, predict how many of the guinea pigs will be heterozygous for the fur length allele.

P.S- the answer is 156, I just want to know how the answer was got.

In a zoo, there are 325 guinea pigs and 52 of them have long fur which are recessive. Using the Hardy-weinberg principle, predict how many of the guinea pigs will be heterozygous for the fur length allele.

P.S- the answer is 156, I just want to know how the answer was got.

Original post by Laychips

Hi, can anyone plz help me with this biology question?

In a zoo, there are 325 guinea pigs and 52 of them have long fur which are recessive. Using the Hardy-weinberg principle, predict how many of the guinea pigs will be heterozygous for the fur length allele.

P.S- the answer is 156, I just want to know how the answer was got.

In a zoo, there are 325 guinea pigs and 52 of them have long fur which are recessive. Using the Hardy-weinberg principle, predict how many of the guinea pigs will be heterozygous for the fur length allele.

P.S- the answer is 156, I just want to know how the answer was got.

p^2 + 2pq + q^2 = 1

The "1" corresponds to the whole population – 325 guinea pigs. For the equation to work, you essentially need to turn the "325" into "1" – do this by dividing by 325. [ratio and proportion etc.]

Now for the q^2 bit, or 52 guinea pigs. To get the proportion, just divide by 325. This is q^2.

p + q = 1

You can calculate q by finding the square root of q^2 from above. Then you can work out p.

Heterozygous = 2pq

So use your values of p and q to calculate the proportion of guinea pigs that are heterozygous.

Then multiply this by the actual population size (325) and bingo you get 156

Apologies if this is a bit of a long-winded/confusing way to go about it!

Reply 2

10 months ago

When doing a Hardy-Weinberg equation, I always start by calculating the q^2 (recessive value), which would be 52/325 in this instance.

You also need to use the p+q=1 equation, so then square root your q^2 value to get the value of q on its own, which can then be taken away from 1 to get the value of p.

From there you have the values for both p and q so can use them in the calculation of 2pq to find the heterozygous phenotype.

Then all you have to do to find the number of individuals in the population with that phenotype is to multiply the 2pq value by the total population (325) which equals 156.

Hope that makes sense? (:

You also need to use the p+q=1 equation, so then square root your q^2 value to get the value of q on its own, which can then be taken away from 1 to get the value of p.

From there you have the values for both p and q so can use them in the calculation of 2pq to find the heterozygous phenotype.

Then all you have to do to find the number of individuals in the population with that phenotype is to multiply the 2pq value by the total population (325) which equals 156.

Hope that makes sense? (:

Original post by butterfliesss

When doing a Hardy-Weinberg equation, I always start by calculating the q^2 (recessive value), which would be 52/325 in this instance.

You also need to use the p+q=1 equation, so then square root your q^2 value to get the value of q on its own, which can then be taken away from 1 to get the value of p.

From there you have the values for both p and q so can use them in the calculation of 2pq to find the heterozygous phenotype.

Then all you have to do to find the number of individuals in the population with that phenotype is to multiply the 2pq value by the total population (325) which equals 156.

Hope that makes sense? (:

You also need to use the p+q=1 equation, so then square root your q^2 value to get the value of q on its own, which can then be taken away from 1 to get the value of p.

From there you have the values for both p and q so can use them in the calculation of 2pq to find the heterozygous phenotype.

Then all you have to do to find the number of individuals in the population with that phenotype is to multiply the 2pq value by the total population (325) which equals 156.

Hope that makes sense? (:

Thank u!!

- TSR Study Together - STEM vs Humanities!
- Edexcel B biology A level exam papers/revison
- Which A-Level Biology should I do? Edexcel A/B
- Alevel PE
- Biology a level
- french or biology a level?
- Websites for a level biology
- Will I need maths A-level or AS level for biology A-level?
- A-Level biology, what is it like?
- Do you need to take A-Level Biology to do well in an Environmental Geography degree?
- Edexcel B Biology Resources
- Are these suitable/realistic a level choices?
- How much Maths in Biology and Psychology A Level?
- Which A level did you find hardest?Bio or Chemistry
- What A levels to pick with biology and psychology?
- Biology AQA A LEVEL
- What university has the lowest GCSE requirements for medicine?
- help ??
- A-level choices
- Can I go into biochem or work in the medical field with these alevels?

- Official Lancaster University Offer Holders Thread for 2024 entry
- MPhil Politics and International Studies 2024
- Is Anyone Seeing Stray Kids At Hyde Park?
- UCL Slade fine art 2024
- Official: University of Birmingham A100 2024 Entry Applicants
- Pupillage Application 2023-2024
- glasgow uni (LAW) rejections?
- What Music do you listen too? ♥
- Official Oxford 2024 Postgraduate Applicants Thread
- Official: Barts and the London (QMUL) A100 2024 Entry Applicants
- Official University of Southampton Applicants for 2024 Entry Thread
- Airbus degree apprenticeships 2024
- Summer Accom in London Needed
- UCL Medicine A100 2024
- Official MPhil Economics/Economic Research etc Cambridge 2024 Thread
- Official: Anglia Ruskin University A100 2024 Entry
- urgent - UAL application
- Will my income from part time job be considered when I apply for student loan?
- Official KCL Offer Holders Thread for 2024 entry
- Official Cambridge Postgraduate Applicants 2024 Thread

- Lloyds Banking Group 2024 Graduate Scheme
- DWP Work Coach Interview - how long to hear
- Official: St George's, University of London A100 2024 Entry
- CTAM: Count to a million (Part 79)
- Apply clearing UCAS
- UCL pharmacy 2024 entry
- DWS Group Graduate P.A.C.E
- MSc in ML/AI in top UK universities with an upper second class honours
- Official: University of Cambridge A101 Applicant and Offer Holder thread 2023 Entry
- Official: University of East Anglia (UEA) A100 2024 Entry
- Oxford MPhil/MPhil + DPhil in Economics 2024
- Mst in English (all streams)
- Architecture Applicants 2024
- Student Finance for non-UK/EEA spouse of UK National
- Histopathology ST1 2024
- Atkins Project Management Graduate Scheme 2024
- Alfa Graduate Orogram
- Still waiting to hear back from Imperial
- Nursing 2024
- Official: University of Sheffield A100 2024 entry

- 2023 Immerse education essay competition
- biology math question ratios alevel aqa
- Advanced Higher Biology Project - any ideas?
- biology aqa alevel proteins question past paper
- Biology essay - importance of proteins in living organisms
- cone concentration
- AQA Biology essay predictions
- Hardy Weinberg question in A level biology please help
- Aqa a level biology paper 3 2023
- a level biology mitosis question

- 2023 Immerse education essay competition
- biology math question ratios alevel aqa
- Advanced Higher Biology Project - any ideas?
- biology aqa alevel proteins question past paper
- Biology essay - importance of proteins in living organisms
- cone concentration
- AQA Biology essay predictions
- Hardy Weinberg question in A level biology please help
- Aqa a level biology paper 3 2023
- a level biology mitosis question

The Student Room and The Uni Guide are both part of The Student Room Group.

© Copyright The Student Room 2024 all rights reserved

The Student Room and The Uni Guide are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: Imperial House, 2nd Floor, 40-42 Queens Road, Brighton, East Sussex, BN1 3XB