BIO END TOPIC REAL

What symbols are used in pedigrees to represent an unaffected female?

An unaffected female is represented by an unshaded circle.

What symbols are used in pedigrees to represent an unaffected male?

An unaffected male is represented by an unshaded square.

What symbols are used in pedigrees to represent an affected female?

An affected female is represented by a fully shaded circle.

What symbols are used in pedigrees to represent an affected male?

An affected male is represented by a fully shaded square.

How can dominant traits be identified in a pedigree?

Affected children must have at least one affected parent.

How can recessive traits be identified in a pedigree?

Unaffected parents can have an affected child because both parents are carriers.

How do you determine phenotype from a pedigree?

Look directly at the shading; shaded means affected and unshaded means unaffected.

What genotype do affected individuals have if the trait is recessive?

All affected individuals are homozygous recessive (aa).

What genotype must unaffected parents of a recessive child have?

They must be carriers (Aa).

What is a mutation?

A mutation is a permanent change in the nucleotide sequence of an organism's DNA.

What is a mutagen?

A mutagen is a physical, chemical, or biological agent that increases the frequency of mutations.

How do mutations affect organisms?

Mutations alter proteins, which can help, harm, or have no effect on an organism.

What is a beneficial mutation?

A beneficial mutation enhances survival chances in a specific environment.

What are examples of beneficial mutations?

Antibiotic resistance in bacteria or lactose tolerance in humans.

What is a neutral mutation?

A neutral mutation has no effect on survival or protein function.

What are examples of neutral mutations?

Silent mutations that code for the same amino acid, or free-hanging earlobes.

What is a harmful mutation?

A harmful mutation decreases survival chances or causes genetic disorders.

What are examples of harmful mutations?

Cystic fibrosis or sickle cell anaemia.

What are gene mutations?

Gene mutations affect a single gene by altering one or a few nucleotide bases.

What is a point (substitution) mutation?

One nucleotide base is swapped for another.

What is an insertion mutation?

An extra nucleotide base is added, shifting the entire reading frame forward.

What is a deletion mutation?

A nucleotide base is removed, shifting the entire reading frame backward.

What is an inversion mutation?

A small section of bases flips 180° backward within the gene.

What are chromosome mutations?

Chromosome mutations alter the structure or number of entire chromosomes, affecting multiple genes.

What is duplication in chromosome mutations?

A segment of the chromosome is copied, resulting in repeating genes.

What is inversion in chromosome mutations?

A segment of the chromosome breaks off, flips upside down, and reattaches.

What is deletion in chromosome mutations?

A large block of genes is lost or deleted from the chromosome.

What is insertion in chromosome mutations?

A piece of one chromosome breaks off and attaches to a non-homologous chromosome.

What is translocation in chromosome mutations?

Two non-homologous chromosomes swap segments with each other.

How do mutations occur?

Mutations occur via environmental factors that damage DNA strands.

How does radiation cause mutations?

High-energy waves break chemical bonds in DNA.

What are examples of radiation mutagens?

UV light causing skin cancer, or X-rays.

How does heat cause mutations?

High temperatures break the bonds linking bases to the DNA backbone.

What is an example of heat causing mutations?

Extreme thermal stress causing cellular damage.

How do chemicals cause mutations?

Molecules insert themselves into DNA or alter base structures.

What are examples of chemical mutagens?

Benzene, asbestos, or cigarette smoke tar.

How do pathogens cause mutations?

Biological agents insert their own genetic material into the host genome.

What are examples of pathogenic mutagens?

Human Papillomavirus (HPV) or certain bacteria.

What is genetic engineering (GMOs)?

Genetic engineering alters organism DNA for agricultural efficiency.

What are the benefits of genetic engineering (GMOs)?

Higher crop yields, pest resistance, and enhanced nutritional value.

What is gene therapy?

Gene therapy inserts functional genes into human cells to replace defective ones.

What are the benefits of gene therapy?

It cures or treats genetic disorders like haemophilia.

Why is variation the foundation of evolution?

If all individuals of a species were genetically identical, an environmental change could wipe out the entire population. Variation ensures some individuals possess traits that allow them to survive, reproduce, and pass those traits on.

What are the five drivers of evolution?

Mutation, gene flow, genetic drift, natural selection, and sexual reproduction.

How does mutation drive evolution?

It creates brand new alleles by altering existing DNA sequences.

How does gene flow drive evolution?

It moves alleles into or out of a population via migration.

How does genetic drift drive evolution?

Random chance events change allele frequencies.

How does natural selection drive evolution?

Environmental pressures favour specific traits over others for survival.

How does sexual reproduction drive evolution?

It mixes existing alleles through crossing over in meiosis and random fertilisation.

Why is genetic diversity important?

High genetic diversity gives a species a wider toolkit to handle ecological disruptions, prevents inbreeding depression, reduces vulnerability to diseases, and ensures long-term species survival during rapid environmental changes.

Who proposed the theory of evolution by natural selection?

Charles Darwin.

What does the theory of evolution by natural selection state?

Organisms best adapted to their environment are more likely to survive and reproduce. Over generations, advantageous heritable traits become more common in the population, changing the species over time.

What does VISTA stand for?

Variation, Inheritance, Selection, Time, and Adaptation.

What is Variation?

Genetic differences exist naturally within a population.

What is Inheritance?

Genetic traits are passed down to offspring.

What is Selection?

Environmental pressures mean more offspring are born than can survive.

What is Time?

Over many generations, successful traits accumulate in the population.

What is Adaptation?

The population becomes better suited to its specific environment.

Why do geographical differences develop within a species?

Natural selection acts differently depending on local environmental pressures.

How can environmental pressures create geographical differences in lizards?

In sandy deserts, lighter-coloured lizards survive better, while in rocky volcanic areas, darker lizards survive better, leading to regional differences over time.

What happens when an environment changes rapidly?

Natural selection filters out non-resistant individuals.

How does antibiotic resistance develop?

Resistant bacteria survive antibiotic treatment and reproduce, passing on the resistance gene until the strain becomes resistant.

How does pesticide resistance develop?

Insects with natural genetic resistance survive pesticide spraying and reproduce, making the pesticide ineffective in future generations.

How does isolation lead to speciation?

Isolation prevents gene flow, allowing populations to diverge into entirely different species.

What is geographical isolation?

Ancestral finches flew from the mainland to different Galapagos islands.

What are different selection pressures?

Each island had different food sources, such as hard seeds, insects, or cactus fruits.

How did VISTA act on the Galapagos finches?

Finches with traits best suited to their island's food source survived and reproduced more successfully.

What is reproductive isolation?

Populations become so different that they can no longer interbreed, forming distinct species.

What is artificial selection?

Artificial selection (selective breeding) occurs when humans deliberately choose which plants or animals breed based on desired traits.

What is the process of artificial selection?

Humans select individuals with preferred traits, breed them together, choose the best offspring, and repeat the process over many generations.

What are examples of artificial selection?

Breeding wild mustard into broccoli and kale, breeding wolves into domestic dog breeds, and increasing milk yield in dairy cows.

What is the selection agent in natural selection?

Environmental pressures such as predators and climate.

What is the selection agent in artificial selection?

Humans.

What is the goal of natural selection?

Survival and reproduction in the wild.

What is the goal of artificial selection?

Human utility, aesthetics, or consumption.

How fast is natural selection?

Very slow, taking thousands to millions of years.

How fast is artificial selection?

Rapid, often taking only a few generations.

How does natural selection affect species health?

It increases evolutionary fitness and survival.

How does artificial selection affect species health?

It can cause health issues, such as breathing problems in pugs.

What is divergent evolution?

Closely related species develop different traits due to different environments.

What is convergent evolution?

Unrelated species develop similar traits due to similar environments.

What type of structures result from divergent evolution?

Homologous structures.

What type of structures result from convergent evolution?

Analogous structures.

What is an example of divergent evolution?

Darwin's finches developing different beak shapes.

What is an example of convergent evolution?

Sharks and dolphins developing streamlined bodies and fins.