Mutations preventing lactose intolerance have occurred in humans at various times in the prehistoric past,
and in all human races.
The domestication of large lactating mammals like goats and cattle arose in Europe and parts of Africa 5 000
to 10 000 years ago.
The lowest levels of lactose intolerance are found in areas that European populations colonised, like North
America.
The ability of agricultural populations to digest the milk, as well as the meat, of animals, is advantageous. It
adds to their general nutrition.
Until recent times the Australian aborigines had been isolated on their island continent for around 50 000
years.
Suggest how the lactose intolerance phenotype came to be present in only 5% of a population like the
Europeans, but came to be present in 97% of the Australian aborigines. Use the information given above and
knowledge of Darwin's theory of evolution by natural selection.
, [9]
2 Bats are the only mammals that have wings. Many species of bat hunt flying insects at night. Bats are able to
use echolocation (sound waves) in order to help them find their prey in the dark.
(i) Explain why bats and birds, despite not being closely related, have both evolved wings.
[3]
(ii) Suggest why the vast majority of bird species have not evolved the ability to echolocate.
, 4(a) In his book ‘On the Origin of Species’, Charles Darwin made the following four observations.
E Offspring generally appear similar to their parents.
F No two individuals are identical.
G Organisms have the ability to produce large numbers of offspring.
H Populations in nature tend to remain relatively stable.
From these observations he made a number of deductions, listed in the table below.
The deductions are supported by one or more of the observations (E, F, G or H).
In the table, indicate which of the above observations contributed to each deduction.
You may use each letter (E, F, G, or H) once, more than once, or not at all.
Deduction Supporting observation(s)
Characteristics are passed on to the next generation.
There is a struggle for existence.
Individuals with beneficial characteristics are among the few who survive.
[3]
(b) Explain how biological molecules can provide evidence that species have evolved.
You should refer to different types of molecule in your answer.
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 mashrooralam. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £0.00. You're not tied to anything after your purchase.