Biology Evolution SCI

Evolution

mechanisms that drives Change in the inherited characteristics (allele frequencies) of populations over generations.

What is biodiversity, and what are its three types?

• Biodiversity: Variety of life on Earth.

• Genetic: Variety of genes and alleles within a species.

• Species: Variety of species in an ecosystem.

• Ecosystem: Variety of ecosystems in an area.

How is biodiversity a result of evolution?

Evolution creates genetic differences and can produce new species over time, contributing to genetic, species and ecosystem diversity.

Why is maintaining genetic diversity important?

provides variation, helping populations adapt to environmental changes and diseases. Low genetic diversity increases extinction risk

What is variation, and why is it important in evolution?

Variation- diffs between individuals of the same species. allows natural selection to favour individuals with advantageous inherited characteristics, which are passed to offspring.

Genes, genotype and phenotype – Define each term.

• Gene: section of DNA containing instructions for a characteristic.

• Genotype: genetic makeup of an organism.

• Phenotype: observable characteristics of an organism, determined by its genes and environmental factors.

Sources of variation – What causes genetic variation?

• Independent assortment: chromosomes separate independently during meiosis.

• Crossing over: homologous chromosomes exchange DNA sections.

• Mutation: changes in DNA create new alleles.

What is a mutation, and why is it important to evolution?

A permanent change in DNA that can create new alleles. may be harmful, neutral or beneficial. only source of new genetic variation and can be inherited if they occur in gametes.

Environmental factors – How can the environment affect phenotype?

influence observable characteristics. Individuals with similar genotypes may develop different phenotypes in diff environments.

Population, gene pool and allele frequency – Define each term.

• Population: Individuals of the same species living in an area at a particular time.

• Gene pool: All alleles/genes within a population.

• Allele frequency: Proportion of a particular allele in the gene pool.

What is the relationship between a gene pool and allele frequency?

gene pool contains all the alleles within a population. Allele frequency describes the proportion of each allele in that gene pool. Evolution occurs when allele frequencies change over generations.

What are selection pressures? Give examples.

Selection pressures are environmental factors that affect an organism's ability to survive and reproduce. Examples include predators, competition for food and water, disease, temperature and natural disasters.

Natural selection – What is natural selection, and what are the steps involved?

occurs when individuals with favourable inherited traits are more likely to survive and reproduce.

1. Variation exists within population.

2. Selection pressures create competition.

3. Individuals with favourable traits survive and reproduce.

4. pass these alleles to offspring.

5. Favourable alleles become more common over generations.

How does natural selection cause antibiotic resistance in bacteria?

• Some bacteria have mutations that make them resistant to antibiotics.

• Antibiotics kill non-resistant bacteria.

• Resistant bacteria survive and reproduce.

• Resistance alleles become more common in the population.

How does natural selection change a population's gene pool?

Individuals with advantageous inherited characteristics are more likely to survive and reproduce. They pass their alleles to offspring, increasing the frequency of those alleles in the gene pool over generations. Less advantageous alleles may become less common.

What are the four main mechanisms that can change allele frequencies in a population?

• Natural selection: Favourable alleles become more common through successful reproduction.

• Mutation: DNA changes create new alleles.

• Gene flow: Alleles move between populations through migration and breeding.

• Genetic drift: Random changes in allele frequencies, especially in small populations or after major events

How does natural selection produce adaptations?

adaptation- inherited characteristic that improves survival and reproduction. Natural selection makes advantageous adaptations more common over generations, e.g differences in colour, size and resistance to antibiotics or pesticides.

Why can the same species develop different characteristics in different locations?

Different environments create diff selection pressures. Natural selection favours diff traits, causing populations to become increasingly different over generations.

What is artificial selection?

Humans choose organisms with desirable characteristics to reproduce, making these traits more common over generations. Example: breeding chickens for larger eggs or more meat.

What is the difference between natural selection and artificial selection?

Natural selection occurs when environmental pressures favour organisms with advantageous characteristics. Artificial selection occurs when humans choose organisms with desirable characteristics to reproduce. Both change the characteristics of populations over generations.

What is the difference between a species and speciation?

• Species: organisms that can breed naturally and produce viable (living) and fertile (able to reproduce) offspring.

• Speciation: the formation of new species.

How does speciation occur?

1. A population becomes separated, often by geographical barrier.

2. Gene flow stops or decreases.

3. Diff environments create diff selection pressures.

4. Mutations and natural selection cause genetic diffs to accumulate.

5. Populations eventually become reproductively isolated and cannot produce fertile offspring together

How can geographical isolation lead to speciation?

physical barrier, such as a river, mountain or ocean, separates populations and prevents gene flow. Diff mutations and selection pressures cause them to become genetically different separate species over time.

What are the four main types of evidence that support the Theory of Evolution?

• Fossils

• Biogeography (geographical distribution)

• Comparative anatomy

• Comparative DNA

What is a fossil?

fossil is the preserved remains, impression or trace of an organism that lived in the past. Examples include bones, footprints and impressions.

fossilisation – What requirements help fossils form?

• Rapid burial by sediment protects remains from decay and scavengers.

• More sediment builds up, creating pressure.

• Minerals preserve or replace hard parts.

• Fossils usually form in sedimentary rock; hard parts fossilise more easily than soft parts.

Fossils – How do fossils support the Theory of Evolution?

show how life has changed over time. Comparing older and newer fossils shows that species have changed, new species appeared and others became extinct.

How does comparing DNA between species support evolution?

Species with more similar DNA sequences are generally more closely related and share a more recent common ancestor. Mutations cause DNA differences to accumulate over generations.

What are Homologous structures

Structures with similar underlying anatomy inherited from a common ancestor, although they may have different functions.

How does the pentadactyl limb support evolution?

Humans, bats, whales and horses share a similar five-digit limb structure. suggests common ancestry, although their limbs have adapted to different functions.

Vestigial organs – What are they? Give examples.

Inherited structures that have lost their original function or have little current function, providing evidence of evolution.

Eg

• human appendix.

• Pelvic bones in whales.

Embryology – How does it support the Theory of Evolution?

Related species often have similar early embryo stages. Features such as tails and gill-like structures suggest common ancestry bc similar development

Biogeography – What is it, and how does it support the Theory of Evolution?

study of the geographical distribution of living and extinct organisms. locations of organisms and fossils provide evidence of common ancestry and how species spread and changed over time.

what ethical issues should be considered when studying heritage sites and artefacts on Country?

• Respect Aboriginal and Torres Strait Islander cultural heritage.

• Protect sites and artefacts from damage.

• Consider ecological impacts of research.

How does comparing protein sequences support evolution?

DNA codes for proteins. Comparing amino acid sequences shows evolutionary relationships. More similar protein sequences generally indicate a more recent common ancestor.

How can isolation and natural selection lead to different species? Give examples.

• Galápagos finches: Diff beak shapes evolved for diff food sources.

• Australian marsupials: Isolated populations developed adaptations for different environments and ecological roles.

How does speciation occur through evolution? (6 marks)

• Variation: Individuals have different inherited characteristics.

• Separation: A geographical barrier prevents gene flow.

• Selection pressures: Different environments create different pressures.

• Survival: Individuals with favourable traits survive and reproduce.

• Inheritance: Favourable alleles become more common over generations.

• Speciation: Genetic differences accumulate until populations cannot produce fertile offspring together.