Summary
OCR A-Level Biology Inheritance and Variation Summary
Handwritten Summary by an Oxford Medical Student which covers all content necessary for an A* in Inheritance and Variation at OCR Biology A-Level.
[Show more]
Seller
Follow
Content preview
variation occurs due to bothgenetic and environmental factors
:
.
Continuous
Polygenetic Characteristic Height/weight
·
spectrum or range
:
-
on a
Discontinuous Monogenetic characteristic with discrete values <Blood Group
·
:
Simple Genetic Cross monogenetic :
characteristics
*
-
a
aa
3 :l phenotypioratio
Heterozygous parents
codominance Both dominant
:
aueles can be expressed ie :
flower colour
↳
Blood Type A :
IP I or I Io Blood Type B I IP or :
II
Type O I I
O
·
II
*
Blood Type AB :
Blood :
*:
I Antigen A produced IP Antigen
:
B produced I: No antigen is produced
Sex Linkage located 23rd
Any gene on the chromosome
:
↳ Recessive conditions occur more females to have unaffected
in males as are more
likely an
dominant X auele ie .
haemophilia or Colour blindness
Dihybrid inheritance :
Inheritance of two characteristics
YyRr x YyRr
tr d
YR
d
F
Yo
2
Y ya ye yo yR
YR YryR yr
YR
YyRR YyR
YR R Ratio 9: 3 3
YyRr Phenotypic 1
:
Yr :
Yyrr
:
yR YyRR YyRr yyRR yyRr ↳
yo YyRr Yyor yyrR yyrr may differ due to mutations or
linkage
Autosomal
linkage Genes are found on the same chromosome
:
↳ No
independent assortment unless separated by chiasmata
↳ Inherited
together
Crossing Over Can :
cause
autosomally linked
genes to Separate
↳ leads to recombinant
offspring Have a different aude combination to parents
:
Recombination
frequency :
Recombinant offspring/ total offspring
↳ <50 %: No linkage
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller faithcortis. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £2.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
73918 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now