Evolution (unfinished read powerpoints to complete)

Question 1

Describe the evolutionary theories and work of other scientists such as Lamarck

Answer 1

Lamarck proposed that organisms could pass on traits acquired during their lifetime.
Example: Giraffes’ necks grew longer because they stretched them to reach leaves, and this trait was inherited by offspring.

Question 2

Describe the contributions of Charles Darwin and Alfred Wallace to the theory of natural selection

Answer 2

Charles Darwin: His study of species in the Galapagos Islands, particularly finches, led to his idea of adaptation. He proposed that individuals with traits better suited to their environment survive longer and produce more offspring, passing those traits on.
Alfred Wallace: Worked in Southeast Asia, observing species variations, particularly in birds. He independently arrived at the same conclusion as Darwin about natural selection, helping solidify the theory.
Both recognized that variation in populations was crucial, and those best suited to the environment survived (survival of the fittest).

Question 3

Define the terms natural selection, allele frequencies, gene pool, and mutations

Answer 3

Natural Selection: The process where individuals with advantageous traits survive and reproduce, passing those traits to the next generation.
Allele Frequencies: The proportion of different alleles of a gene in a population.
Gene Pool: The total collection of genes and their alleles within a population.
Mutations: Changes in DNA that create genetic variation, some of which may be advantageous or disadvantageous.

Question 4

State and describe how the 4 steps of Natural Selection results in permanent changes in the frequency of alleles in a population

Answer 4

Variation: Individuals in a population have differences.
Selection Pressure: Environmental factors favor certain traits.
Survival of the Fittest: Individuals with favorable traits survive and reproduce.
Allele Frequency Change: Over generations, advantageous alleles become more common in the population.

Question 5

Identify different selection pressures and how they change the allele frequency of populations over time (example Finches on the Galapagos Islands, evolved into different species to eat different foods)

Answer 5

Selection Pressures: Environmental challenges that affect an organism’s survival, such as predators, diseases, food availability, or changes in climate.
Example: Galapagos Finches: Different islands had different food sources (seeds, insects), so finches evolved different beak shapes to specialize in certain diets. This is an example of adaptive radiation.
Allele Frequency Changes: If a particular trait helps survival (e.g., thicker beaks for eating tough seeds), the alleles for that trait increase in the population.

Question 6

Describe and discuss the process of speciation in 3 steps

Answer 6

. Variation: There must be variation in the population​

2. Isolation: This means that different groups must be prevented from interbreeding, this stops any differences from one population reaching the other population​
3. Selection: Natural selection affects the genotype and causes changes (mutations) that prevent the groups breeding even if they got back together.​

Question 7

Understand the different types of genetic isolation and how this prevents genetic flow/ mating between populations.

Answer 7

Genetic isolation happens when populations are prevented from mating and exchanging genes, which blocks gene flow. This can occur through:

Geographical isolation: Physical barriers like mountains or rivers separate populations, preventing them from meeting.
Ecological isolation: Populations live in different environments within the same area, so they don’t interact or mate.
Temporal isolation: Populations breed at different times (seasonal or daily), so mating doesn’t occur.
Behavioral isolation: Differences in mating behaviors, such as courtship rituals, prevent interbreeding.
These barriers stop populations from exchanging genes, leading to reproductive isolation.

Question 8

Identify homologous and analogous structures when comparing the evolution of different organisms

Answer 8

Homologous Structures: Structures that have a similar origin but may serve different functions in different species. Example: The forelimbs of humans, cats, whales, and bats have the same bone structure but are used for different functions (grasping, walking, swimming, and flying).
Analogous Structures: Structures that have different origins but perform similar functions in unrelated species. Example: Wings of birds and insects serve the same function (flight) but evolved separately.

Question 8

Understand the difference between divergent and convergent evolution

Answer 8

Divergent Evolution: When two species evolve in different directions from a common ancestor. Over time, they develop different traits suited to their environments. Example: Darwin’s finches evolved different beaks to exploit various food sources.
Convergent Evolution: When unrelated species evolve similar traits because they live in similar environments or face similar selection pressures. Example: Sharks (fish) and dolphins (mammals) both developed streamlined bodies to swim efficiently in water.

Question 9

Be able to explain how similar selection pressures can cause convergence

Answer 9

Similar selection pressures (e.g., aquatic environments) cause unrelated species to develop similar traits through convergent evolution.

Question 10

Be able to explain how different selection pressures can cause divergence and the formation of new species

Answer 10

Different selection pressures (e.g., climate, food availability) cause populations to evolve into new species through divergent evolution.

Question 11

Identify suitable conditions required for fossilisation

Question 11

Outline the steps that lead to fossil formation

Question 12

Understand how Relative dating techniques is used to determine the relative age of fossils

Question 12

Define Transitional fossils and discuss their importance

Answer 12

Transitional fossils show intermediate forms between an ancestral species and its descendants, providing evidence for gradual evolution.
Example: Archaeopteryx is a transitional fossil between reptiles (dinosaurs) and birds, showing features like teeth and a long tail, but also feathers and wings.
These fossils help scientists understand how major groups of organisms evolved over time.
(Between land and water)

Question 12

Types of evidence supporting evolution, including fossil records, comparative anatomy, embryology, molecular biology, biogeography, and observable evolutionary changes.