evolution exam questions Flashcards
suggest three possible limitations of this investigation (3)
-10 minutes may not be long enough for females to make final decision
-lab guppies may react in different way to wild guppies
barrier may not allow for normal courtship behaviour.
guppies with large brains are better at identifying predators.
scientists found that only female guppies with large brains were attracted to male guppies bright in colour.
suggest and explain the advantage of this behaviour to the population of guppies. (3)
-large brained females mate with coloured male guppies
-offspring more likely to be coloured.
offspring attract larger brained females
evolution to have larger brains
population better at identiying predators.
describe how the behaviour of female gupplies could result in sympatric speciation- 3 marks
-no geograhic barrier
-reproductive isolation
-no longer able to interbreed to produce fertile offspring
-changes in allele frequency.
describe how farming cattle as a source of milk could have led to LP. (3)
-LP produced by mutation
-organisms with LP more likely to survive and reproduce.
-milk provides glucose
-frequency of allele increases over generations.
using this information, sugggest how these two species of palm tree arose via sympatric speciation (5)
mutations cause different flowering times.
reproductive isolation
different alleles passed on
disruptive natural selection
eventually species cannot interbreed to produce fertile offspring.
why is there a high frequency of this mutation in yaramul (2)
isolated so inbreeding
allele inherited from common ancestor.
explain why natural selection has not reduced the frequency of the mutation in the population. (1)
organisms have already reproduced.
there was a time lag between the introduction of the Bt crop and the appearence of the first insect species resistant to the Bt toxin.
Explain why there was a time lag. (3)
initially only few organisms with favourable allelle
these organisms will have the most offspring.
takes many generations for allele to become the most common.
explain how different subspecies of girrafe may have evolved from a common ancestor. (5)
mutations create different coloured markings
coloured markings enable survival.
-reproductive isolation
-differential reproductive success
-changing allele frequencies.
Read the following passage.
Lake Malawi in East Africa has more species of fish than any other lake in the world. Many of these species have evolved from a common ancestor. Lake Malawi is one of the largest lakes in the world and was formed several million years ago. Since then, the water level has fluctuated greatly. As a result,
5 what is now a large lake was at one time many smaller, separate lakes.
The country of Malawi has a total area of 118 000 km2. The actual land area is only 94 080 km2, because approximately one-fifth of the country is Lake Malawi.
In December 1990, forests covered 41.4% of the actual land area of Malawi. 10 In December 2016, forests covered 26.4% of the actual land area of Malawi.
Deforestation and farming along the shores of Lake Malawi have caused increased soil erosion and loss of nutrients into the lake. This has resulted in a decrease in some fish populations. The mark-release-recapture method can be used to estimate the size of a fish population. However, this method can
15 produce unreliable results in very large lakes.
Use the information in the passage and your own knowledge to answer the following questions.
(a) Lake Malawi in East Africa has more species of fish than any other lake inLake Malawi in East Africa has more species of fish than any other lake in the world (line 1).
Suggest and explain how this speciation may have occurred. (4)
-allopatric speciation
-reproductive isolation
-changes in allele frequencies
-organisms no longer able to interbreed to produce fertile offspring.
-mutations produce differences
on isladns in the carribean, there are alost 150 species of lizards belonging to the genus anolis. Scientists believed that these species evolved from two species found on mainland USA. Explain how the carribean species could have evolved. (5)
-reproductive isolation
-no gene flow
-changes in allele frequency
-differential reproductive success
-variation due to mutation.
explain the advantage of presenting results as a ratio
allows comparison
sample size/numbers may be different.
the allele for normal haemoglobin in red blood cells is HBA. in some parts of africa where malaria occurs there is a high frequency in the population of the allele HBC. Individuals with the HBC allele have a lower chance of developing severe malaria. Severe malaria causes a large number of deaths in africa.
Explain the high frequency of the HBC allele in areas where malaria occurs. (3)
-individuals with HBc allele reproduce
-allelle inherited by offspring so frequency of allele increases.
individuals with HBA allele are less likely to survive and reproduce.
use the information provided to explain how a very high diversity of bird species has developed in the amazon rainforest. (5)
-reproductive isolation
-differential reproductive success
-changes in allele frequency
-mutation
-different selection pressures.
speciation is far less frequent in reformed amazon rainforest.
Suggest one reaeson for this. (1)
no isolation
