10 Biology Evolution

Genetic Trait

A trait inherited from parents through DNA

3 examples of genetic traits

Eye colour, blood type, natural hair texture.

Acquired trait

A trait developed during an individual's lifetime due to the environment or learning

3 examples of acquired traits

Muscle development from exercise, scars, learned skills

Can acquired traits be passed to offspring?

No.

genetic variation

Differences in genetic traits between individuals in a population.

4 ways genetic variation can arise

Mutation, genetic recombination, random mating and gene flow.

Mutation

A random change in the DNA sequence that can create new alleles.

What happens during genetic recombination?

Parental chromosomes are mixed during meiosis, creating unique combinations of genes.

Gene flow

The movement of genes between populations, usually through migration.

Evolution

Biological change that occurs in living things over generations.

Why is variation important for evolution?

It provides differences for natural selection to act upon.

Does evolution occur within one individual during its lifetime?

No. Evolution occurs across generations in populations.

What happens to beneficial traits over generations?

They become more common in the population.

What happens to less helpful traits?

They become less common.

Natural selection

The process where organisms with favourable traits are more likely to survive and reproduce

3 key elements needed for natural selection

Variation, inheritance and selection

Variation

Individuals in a population have different traits

Inheritance

Traits can be passed from parents to offspring

Selection

Some traits provide advantages for survival and reproduction

Selection pressure

An environmental factor that influences an organism's survival and reproduction

4 examples of selection pressures

Predators, disease, food availability and climate conditions

What happens to advantageous traits in a population

They become more common over generations

Does natural selection create new traits?

No. It acts on existing variation within a population.

What were the two colour variations of peppered moths

Light-coloured and dark-coloured

Why were light moths advantageous before the Industrial Revolution

They were better camouflaged against light-coloured tree bark

What happened to the trees during the Industrial Revolution

Pollution darkened the tree bark

What was the selection pressure of the moths?

Predication

Why did dark moths become more common

They were better camouflaged, so more survived and reproduced

Adaptation

A genetic trait that helps an organism survive in its environment

Structural adaptation

A physical feature that helps an organism survive

Physiological adaptation

An internal bodily process that helps an organism survive

Behavioural adaptation

A behaviour or action that helps an organism survive

How do adaptations develop

Through natural selection over many generations

Do organisms consciously choose their adaptations

No. Adaptations result from beneficial genetic variations being favoured by natural selection

What is an antibiotic?

A medicine that kills bacteria or prevents their growth

How do antibiotics act as a selection pressure?

They kill susceptible bacteria, while naturally resistant bacteria survive and reproduce

What happens to resistant bacteria after susceptible bacteria die?

They multiply and become more common in the population.

Do antibiotics cause bacteria to mutate into resistant bacteria

some bacteria already have genetic mutations that allow them to survive. The antibiotic selects for these resistant bacteria

3 things that increase antibiotic resistance

Not completing treatment courses, unnecessary antibiotic use, and frequent antibiotic use in livestock

Superbugs

Bacteria resistant to multiple antibiotics

Why is antibiotic resistance dangerous?

It can cause longer recovery, more expensive treatment, complications and fewer effective treatment options.

What does fossil evidence show?

How species have changed over millions of years

What is a transitional fossil?

A fossil showing features linking different groups of organisms

What is an example of a transitional fossil

Archaeopteryx

What are homologous structures?

Structures with a similar basic arrangement that evolved from a common ancestor but may have different functions

What are vestigial structures?

Reduced or functionless structures that had a purpose in ancestors

An example of a vestigial structure

The human tailbone

Analogous structures

Structures that perform similar functions but evolved independently

An example of analogous structures

Bird wings and insect wings

What does DNA evidence tell us?

More closely related species generally have more similar DNA sequences

Biogeography

The study of how species are distributed across Earth and what this can reveal about evolution.

What does embryological evidence suggest?

Similarities in early embryos suggest organisms share common ancestry.

Species

A group of organisms that can interbreed and produce fertile offspring

Speciation

The formation of a new species

Geographic isolation

When a population becomes separated by a physical barrier

3 examples of geographic barriers

Mountains, rivers and oceans

What happens to isolated populations over many generations

They experience different environmental pressures, accumulate genetic differences and develop different adaptations

Reproductive isolation

When populations can no longer successfully mate and produce fertile offspring

Basic sequence of speciation

Geographic isolation → different selection pressures → genetic differences → reproductive isolation → new species

4 factors that can contribute to extinction

Habitat loss, climate change, overexploitation and pollution

2 examples of habitat loss

Deforestation and urban development

2 examples of overexploitation

Overhunting and overfishing

3 ways endangered species can be protected

Protected areas, captive breeding and reintroduction programs

What are wildlife corridors?

Areas that connect habitats and allow wildlife to move between them