Evolution Evidence (5.1)

Question 1

Define biological evolution

Answer 1

A change in the allele frequency of a population’s gene pool over successive generations.

Question 2

Define microevolution

Answer 2

Small changes that occur over a short period of time and lead to the formation of new breeds or bacterial strains.

Question 3

Define macroevolution

Answer 3

Large changes that occur over a long period of time and lead to the formation of new species and even phylum.

Question 4

What provides evidence for evolution and how?

Answer 4

The fossil record because it reveals the features of an ancestor which can be used to compare against living descendants.

Question 5

The Fossil Record

Answer 5

The totality of fossils, both discovered and undiscovered.

Question 6

The Law of Superposition

Answer 6

Within a sequence of layers of rock, the oldest layer is at the base and the newest layer is at the top.

Question 7

How does The Law of Superposition help us?

Answer 7

It allows us to relatively figure out the age of different fossils by dating the rock that it is fossilised in.

Question 8

The Law of Fossil Succession

Answer 8

The ordered succession of fossils. It suggests that newer species likely evolved as a result of changes to ancestral species.

Question 9

What are transitional fossils?

Answer 9

Intermediary forms that establish links between species by exhibiting traits common to both the ancestor and its predicted descendants.

Question 10

How do fossils provide evidence for evolution?

Answer 10

By comparing hominin skeletons.

Australopithecus first appeared in the fossil record approx. 4 million years ago. We can compare this fossil with the bone structure of homo sapiens today and see marked developments.

Question 11

What is selective breeding?

Answer 11

Selecting specimens to breed based on the desirability of their traits. Artificial selection.

Question 12

Outline two potential harms of selective breeding

Answer 12

Less genetic variation and inbreeding (this can cause health problems).

Question 13

Define homologous structures

Answer 13

Structural similarities in groups of organisms that suggest they all share a common ancestor.

Question 14

Define adaptive radiation

Answer 14

A type of divergent evolution.

A common ancestor evolves into a large number of species to occupy distinct niches with different environmental conditions.

Question 15

Give an example of homologous structures

Answer 15

The pentadactyl limb is seen in a variety of animals indicating a common ancestor. Mammals, birds, amphibians and reptiles all share similar appendage structures. However, these are all used for different forms of locomotion. Their common ancestor was early amphibians.

Question 16

Define analogous structures

Answer 16

Features of different species that are similar in function but not necessarily in structure and do not derive from a common ancestral feature. They are the result of convergent evolution.

Question 17

Define convergent evolution

Answer 17

When species occupy similar ecological niches and adapt in similar ways in response to similar environmental pressures.

Question 18

Define divergent evolution

Answer 18

When two or more species evolve/diverge from a common ancestor.

Question 19

Define vestigial structures

Answer 19

Functionless and reduced remnants of organs that were once present in their ancestors. Changes to the environment have meant they have lost their functionality.

They demonstrate the evolutionary divergence of a species.

Question 20

Define biogeography

Answer 20

The distribution of lifeforms over geographical areas.
Related species are usually found in close physical proximity. This suggests that closely distributed species share a common lineage, providing evidence for evolution.

Question 21

Define comparative embryology

Answer 21

The study of the growing embryo in animals and plants.
Closely related species go through similar stages of development. This suggests that the organisms shared a common evolutionary pathway, providing evidence for evolution.

Question 22

Define speciation

Answer 22

The evolutionary process by which two related populations diverge into separate species.

Question 23

When are populations of species considered to be ‘separate species’?

Answer 23

When the two populations can no longer interbreed and produce fertile, viable offspring.

Question 24

Define reproductive isolating mechanisms

Answer 24

Factors that prevent populations from reproducing successfully with one another. Eg. geographical separation, and behavioural isolation.