L5: Theory of Evolution

Question 1

What is evolution?

Answer 1

A gradual change in the inherited traits of a population over time. Occurs due to natural selection

Question 2

Outline the theory of natural selection

Answer 2

1. Variation occurs due to genetic mutation
2. There is competion between organisms
3. A mutation may give an organism a survival advantage
4. Organism is better adapted to environment and survives
5. Organism reproduces, passing on beneficial alleles
6. Frequency of advatageous alleles increases in a population over many generations

Question 3

Why does competitions between organisms in a habitat exist?

Answer 3

The resources within a habitat required for survival are limited

Question 4

Give some examples of competitions between organisms within a habitat

Answer 4

• Competition between animals for food, water, shelter, mates etc.
• Competition between plants for light, water, mineras etc.

Question 5

Define species

Answer 5

A group of similar organisms that are able to breed to produce a fertile offspring

Question 6

Define speciation

Answer 6

The formation of a new species in the course of evolution, often due to the evolution of two isolated populations

Question 7

Explain how a physical barrier may result in speciation

Answer 7

• A physical barrier (eg. deforestation) seperates two populations of the same species
• The two populations experience different environmental conditions
• They experience different selective pressures
• The evolve with different traits
• Eventually the two become different species

Question 8

How can the observation of fossils provide evidence for evolution?

Answer 8

• Older fossils (found in ocks deeper in the ground) contain simpler organisms.
• Newer fossils (closer to surface) have more complex organisms
• The comperison of the two show that simple life forms have evolved into more complex ones
• Fossils can be organised into chronological order, allowing for the changes in organisms to be observed

Question 9

Describe how antibiotic resistance in bacteria illustrates the process of evolution

Answer 9

1. Variation within a population exists due to genetic mutation
2. A mutation may give the bacterium antibiotuc resistance
3. If an antibiotic is used, the bacterium is better adapted and survives, whilst other bacteria are killed
4. Pacterium reproduces, passing on its resistant variant
5. Frequecy of the antibiotic resistant allele increases

Question 10

Why is the development of antibiotic resistance in bacteria good evidence and study for evolution?

Answer 10

Because they reproduce very rapidly, allowing the first-hand observation of evolution

Question 11

Using what evidence did Darwin and Wallace develop the theory of evolution?

Answer 11

• Fossil evidence
• Selective breeding
• Comparisons of the traits of isolated populations of the same species

Question 12

What is selective breeding?

Answer 12

The process by which humans artificially select organisms with desirable characteristics and breed them to produce offspring with similar phenotypes

Question 13

Outline the main steps involved in selective breeding

Answer 13

1. Identify a desired chracteristic eg. disease resistant
2. Select the best parent organisms that shiw the desired traits
3. Breed them together
4. Select offspring with desired traits and breed them
5. Repeat process for many generations until all offspring have desirable traits

Question 14

What is the main advantage of selective breeding?

Answer 14

Creates organisms with desirable features:
* Crops produces a higher yield of grain
* Cows produce a greater supply of milk
* Plants produce a larger fruit

Question 15

What are the 4 disadvantages of selective breeding?

Answer 15

• Less variation/reduction in gene pool (which becomes especially harmful if a sudden change in envirnment occurs)
• Inbreeding results in genetic disorders
• Development of other physical problems eg. respiratory problems in bulldogs
• Unknowingly selecting harmful recessive alleles

Question 16

How can selective breeding provide evidence for evolution?

Answer 16

Selective breeding demonstrates that traits can be passed down from parents to the offspring

It shows that new varieties of organisms can gradually form with time as desired traits are selected. This can be applied to natural selection in the wild

Question 17

How can comparisons of the traits of isolated populations of the same species provide evidence for evolution?

Answer 17

Comparisons of the populations that were once one species show that members of the same species may evolve deifferently whin living in different environments

Question 18

Why do some accept the theory of evolution?

Answer 18

• A large amount of evidence supports this theory
• Previously collated data may support this theory
• They may have conducted their own research and come to a similar conclusion

Question 18

How has the thoery of evolution by natural selection impacted modern biology and society?

Answer 18

• Enables the classification of the organisms into taxa
• Influences modern medicine by emphasising the importance of finishing antibiotic treatments and the need for the constant production of new ones
• Highlights the importance of high genetuc diversity in habitats which aids conservation projects

Question 19

Why do some not accept the theory of evolution?

Answer 19

• It ay contradict religious beliefs
• Different people may interpret the evidence in defferent ways
• Lack of understanding or awarenes of the evidence that supports evolution
• The fossil record is incomplete
• It is a theory

Question 20

What evidence is there for evolution?

Answer 20

• Fossils
• Selective breeding
• Modern day examples of evolution
• Differences in isolated populations