Evolution & Speciation (SL IB Biology)

What is the most important requirement for speciation to occur?

Why do species evolve over time?

The image below shows a series of fossils.

How does this set of fossils provide evidence for evolution?

The diagram below shows how selective breeding has developed several modern crop varieties from wild wheat.

The selective breeding of modern wheat from wild wheat would begin with the breeders selecting individuals with many, large seeds.

What is the correct continuation of the process for the selective breeding of modern wheat from wild wheat?

Melanin is a dark pigment produced in the cells; higher melanin production results in an organism's darker colour.

It has been noted that melanistic peppered moths have become more common than non-melanistic individuals in industrialised parts of the UK where air pollution has increased.

Air pollution kills organisms, called lichens, that grow on the bark of trees. Areas with clean air have more lichen resulting in trees of a lighter colour compared to polluted areas where lichen are killed, causing tree trunks and branches to appear darker.

Which of the following is not a reason for the evolution of melanism in peppered moths?

From the three examples listed below, which describe the occurrence of speciation?

I. Two plant populations of the same species are pollinated by different species of insect that are active at different times of the day. There is no overlap between when the two insect species are active. Mutations occur within the two populations leading to them to become genetically distinct from each other. 

II. A small number of lizards float on a wooden log and start a new population on another island. Mutations occur within the two populations leading to them to become genetically distinct from the original population.  

III. A mutation occurs that causes a small population of a species of plant to become tetraploid instead of the usual diploid cells.

Several species of lava lizard of the genus Microlophus are found only in the islands of the Galapagos. A group of scientists recorded the mating displays of male lava lizards in different parts of the Galapagos, using the amplitude of a wave to represent the height and length of head bobbing behaviour. The map shows the mating displays of some male lava lizards currently living on different islands of the Galapagos.

Which of the following statements about mating displays in Galapagos lava lizards are correct?

I. Mating displays are the same between members of the same species of lava lizard

II. Mating displays show continuous variation across the geographical range of the Galapagos lava lizards

III. The mating displays suggest that lava lizards evolved by gradual divergence from a common ancestor

IV. The mating displays recorded show all the stages of lava lizard divergence

The pelvic bones of whales are located in the equivalent position to the hip bones of land mammals, though they are not attached to the rest of the skeleton. These bones have long been thought of as vestigial structures leftover from the process of evolutionary change. Scientists researched the relationship between the size of whale pelvic bones and the size of whale testes. The graphs show some of the results of the study.

Which of the following statements relating to whale pelvic bones are correct?

I. Whale pelvic bones are homologous to the pelvic bones of land mammals.

II. There is no relationship between the body size of a whale, as represented by rib size, and the size of a whale's testes.

III. The pelvic bones of whales are vestigial structures with no function.

IV. The pelvic bones of whales are not vestigial but are involved in reproduction.