E&B: Evidence For Evolution

Question 1

What is evolution?

Answer 1

Evolution is the cumulative changes in heritable characteristics of a population over time

Question 2

How does comparative embryology suggest occurrence of evolution?

Answer 2

Studying the growing embryo in plants/animals show that closely related species go through similar stages of development. These similarities in embryonic development suggest that the organism shared a common evolutionary theory.

Question 3

How does study of fossils suggest occurrence of evolution?

Answer 3

Fossils found in lower layers of the soils are less complex than those found at the upper, showing that organisms became more complex with time.

Question 4

Limitations of paleontology?

Answer 4

Missing links of fossil records, either because they have been destroyed by scavengers, decomposition, other fossils have not been discovered.
Distortion of some fossil parts due to sedimentation.
Destruction of fossils by geological activities, earthquake.
Resulting in false conclusions being drawn.

Question 5

Describe Chemical evolution theory?

Answer 5

It postulates that life came into being through a combination of chemical elements such as hydrogen, oxygen, nitrogen,carbon.

Question 6

How did evolution occur according to chemical evolution theory?

Answer 6

Through catalytic effect of frequent lightning, high temp and pressure these elements were combined to form simple molecules such as ammonia, methane, hydrogen.

The simple molecules then combined to form complex molecules such as lipoprotein, polysaccharides, and self-replicating molecules similar to dna.

Successive replication of this molecules and further development led to formation of simple cellular organisms resembling the present day bacteria.

The simple life forms underwent a series of changes over a long time giving rise to present generation of living organisms.

Question 7

How does comparative serology prove occurrence of evolution?

Answer 7

In the reactions between antiserum and serum of the compared animals, The higher the precipitate the closer the relationship between the animals being compared.

Question 8

How does biogeography prove occurrence of evolution?

Answer 8

Fossils found in a particular region tend to closely resemble the modern organisms of the region. It suggests that closely distributed organisms share a common lineage.

Question 9

How does cell biology prove occurrence of evolution?

Answer 9

All eukaryotic cells contain the same organells as mitch, ribosome, biological chemicals such as atp, dna, rna. These similarities indicate that all cell types have a common ancestral origin.

Question 10

What are homologous structures?

Answer 10

Anatomical features that are similar in basic structure despite being used in different ways.

Question 11

How does homologous structures illustrate adaptive radiation?

Answer 11

Several new species rapidly diversify from an ancestral source, with each new species adapted to utilise a specific unoccupied niche.

Question 12

Define divergent evolution?

Answer 12

Divergent evolution is the process whereby groups from the same common ancester evolve and accumulate differences, resulting in the formation of new species.

Question 13

Define convergent evolution?

Answer 13

Convergent evolution is when two species with different ancestral origins develop similar characteristics.

Question 14

What are analogous structures

Answer 14

Structures with different ancestral origins but modified to perform similar functions.

Question 15

Examples of analogous structures?

Answer 15

Shape of dogfish and dolphins, the wings of an insect and a bat.

Question 16

What are vestigial structures?

Answer 16

Structures that have greatly reduced in size and became function less due to disuse over a long period of time.

Question 17

Vestigial structures eg?

Answer 17

Ear muscles, appendix, body hair.

Question 18

Explain lamarck’s theory of use and disuse

Answer 18

Lamarck proposes that body structures develop in organisms when need arises.The environmental condition dictates the development of a specific structure.

Question 19

Limitations of lamarck’s theory?

Answer 19

From the knowledge of genetics, the acquired characteristics cannot be inherited since they do not affect the genotype.

Question 20

Define selective breeding

Answer 20

a form ofartificial selection, whereby man intervenes in the breeding of species to produce desired traits in offspring

Question 21

How does selective breeding prove that evolution occurred

Answer 21

By breeding members of a species with a desired trait, the trait’s frequency becomes more common in successive generations
Selective breeding provides evidence of evolution as targeted breeds can show significant variation in a (relatively) short period

Question 22

Explain the process of natural selection

Answer 22

Mnemonic:ICE AGE

The process of natural selection occurs in response to a number of conditions:

• Inherited Variation– There is genetic variation within a population which can be inherited

• Competition– There is a struggle for survival (species tend to produce more offspring than the environment can support)

• Selection– Environmental pressures lead to differential reproduction within a population

• Adaptations– Individuals with beneficial traits will be more likely to survive and pass these traits on to their offspring

• Evolution– Over time, there is a change in allele frequency within the population gene pool