Science - Biology: Where Do We Come From?

Biology Where Do We Come From? – What is evolution?

The gradual change in the inherited characteristics of a population over successive generations

Biology Where Do We Come From? – Does an individual organism evolve?

No, populations evolve over generations as the frequency of inherited characteristics changes

Biology Where Do We Come From? – What is a species?

A group of organisms that can reproduce with each other and produce fertile offspring

Biology Where Do We Come From? – What is biodiversity?

The variety of different living organisms within an ecosystem or across Earth

Biology Where Do We Come From? – What is evidence for evolution?

Scientific observations and discoveries that demonstrate how organisms have changed over time and share common ancestors

Biology Where Do We Come From? – What are the main types of evidence supporting evolution?

Fossil records, homologous structures, similarities in embryonic development and DNA evidence

Biology Where Do We Come From? – What are homologous structures?

Structures in different species that have a similar underlying anatomy because they were inherited from a common ancestor

Biology Where Do We Come From? – How do homologous structures provide evidence for evolution?

They suggest that different species evolved from a common ancestor, even if the structures now perform different functions

Biology Where Do We Come From? – Give an example of homologous structures

The forelimbs of humans, whales, bats and cats have similar underlying bone arrangements despite having different functions

Biology Where Do We Come From? – What are embryonic similarities?

Similarities between the embryos of different species during early stages of development

Biology Where Do We Come From? – How do embryonic similarities support evolution?

Similarities in early development suggest that different species may have inherited developmental features from a common ancestor

Biology Where Do We Come From? – What is molecular evidence for evolution?

Evidence from comparing DNA and protein sequences between different organisms

Biology Where Do We Come From? – How does DNA evidence support evolution?

Species with more similar DNA sequences are generally more closely related and likely share a more recent common ancestor

Biology Where Do We Come From? – What does it suggest if two species have very similar DNA?

They are likely to share a relatively recent common ancestor

Biology Where Do We Come From? – What is the fossil record?

The collection of fossils found in rock layers that provides evidence of organisms that lived in the past

Biology Where Do We Come From? – What is a fossil?

Preserved remains, traces or impressions of organisms that lived in the past

Biology Where Do We Come From? – How do fossils provide evidence for evolution?

They show how organisms have changed over time and reveal species that existed in the past, including extinct species

Biology Where Do We Come From? – What is an extinct species?

A species that no longer has any living members

Biology Where Do We Come From? – What are transitional fossils?

Fossils showing features that are shared between an ancestral group and a later group, providing evidence of evolutionary change

Biology Where Do We Come From? – How do transitional fossils support evolution?

They show combinations of characteristics that help demonstrate how groups of organisms changed over time

Biology Where Do We Come From? – Why is the fossil record incomplete?

Fossilisation is rare, many organisms decompose before becoming fossils, and some fossils have not yet been discovered

Biology Where Do We Come From? – What is the geological timescale?

A system used to organise Earth's history into periods of time based on geological and biological events

Biology Where Do We Come From? – Why is the geological timescale important?

It allows scientists to organise fossils and understand when different organisms lived and how life changed over Earth's history

Biology Where Do We Come From? – What is relative dating?

A method used to determine whether a rock or fossil is older or younger than another without finding its exact age

Biology Where Do We Come From? – How does the principle of superposition work?

In undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest layers are at the top

Biology Where Do We Come From? – How can superposition be used to date fossils?

Fossils found in lower undisturbed rock layers are generally older than fossils found in layers above them

Biology Where Do We Come From? – What is an index fossil?

A fossil from a species that was widespread but existed for a relatively short geological period

Biology Where Do We Come From? – What characteristics make a good index fossil?

It should be widespread, easily recognised and have existed for a relatively short period of time

Biology Where Do We Come From? – How are index fossils used in relative dating?

They allow scientists to compare the ages of rock layers in different locations containing the same index fossil

Biology Where Do We Come From? – What is one advantage of relative dating?

It allows scientists to compare the ages of rocks and fossils without needing to determine their exact numerical ages

Biology Where Do We Come From? – What is one limitation of relative dating?

It cannot provide an exact numerical age for a rock or fossil

Biology Where Do We Come From? – What is absolute dating?

A method used to determine the approximate numerical age of rocks or fossils

Biology Where Do We Come From? – How does radiometric dating work?

It measures the decay of radioactive isotopes into more stable substances at a predictable rate

Biology Where Do We Come From? – What is a radioactive isotope?

An unstable form of an element that releases radiation as it decays over time

Biology Where Do We Come From? – What is a half-life?

The time taken for half of the radioactive atoms in a sample to decay

Biology Where Do We Come From? – How can half-life be used to determine age?

Scientists measure the amount of radioactive parent isotope remaining and use its known half-life to estimate the sample's age

Biology Where Do We Come From? – What is carbon dating?

A type of radiometric dating that measures the decay of carbon-14 in once-living material

Biology Where Do We Come From? – What materials can carbon dating be used on?

Relatively recent organic remains, such as wood, bones and other once-living materials

Biology Where Do We Come From? – Why can't carbon dating be used to date very ancient fossils?

Carbon-14 has a relatively short half-life, so too little remains in very old samples to measure reliably

Biology Where Do We Come From? – What is one advantage of absolute dating?

It provides an estimated numerical age for rocks or fossils

Biology Where Do We Come From? – What is one limitation of absolute dating?

It can be difficult to date fossils directly, and results may be affected by contamination or unsuitable samples

Biology Where Do We Come From? – What is the difference between relative and absolute dating?

Relative dating determines whether something is older or younger, whereas absolute dating estimates its numerical age

Biology Where Do We Come From? – Who developed the theory of evolution by natural selection?

Charles Darwin

Biology Where Do We Come From? – What is natural selection?

The process in which organisms with advantageous inherited characteristics are more likely to survive and reproduce, passing those characteristics to their offspring

Biology Where Do We Come From? – What is variation within a population?

Differences in characteristics between individuals of the same species

Biology Where Do We Come From? – What causes genetic variation within a population?

Mutations, crossing over, independent assortment during meiosis and random fertilisation

Biology Where Do We Come From? – Why is variation important for natural selection?

It means individuals have different characteristics, some of which may provide an advantage in a particular environment

Biology Where Do We Come From? – What is an adaptation?

An inherited characteristic that improves an organism's ability to survive and reproduce in a particular environment

Biology Where Do We Come From? – What are the main steps of natural selection?

Individuals vary, some variations provide a survival or reproductive advantage, those individuals reproduce more successfully and advantageous alleles become more common over generations

Biology Where Do We Come From? – Why do organisms with advantageous characteristics tend to reproduce more successfully?

They are more likely to survive environmental pressures and produce offspring, passing their advantageous alleles to the next generation

Biology Where Do We Come From? – How does natural selection change a population over generations?

Advantageous inherited characteristics become more common, while less advantageous characteristics may become less common

Biology Where Do We Come From? – Does natural selection create characteristics because organisms need them?

No, variation already exists through processes such as mutation, and natural selection favours inherited variations that provide an advantage

Biology Where Do We Come From? – How can environmental changes affect evolution?

Environmental changes create new selection pressures, favouring individuals with characteristics that improve survival and reproduction under the new conditions

Biology Where Do We Come From? – What is a selection pressure?

An environmental factor that affects an organism's chances of survival and reproduction

Biology Where Do We Come From? – Give examples of selection pressures

Predators, disease, competition, climate, food availability and changes in habitat

Biology Where Do We Come From? – Why might a characteristic that was once advantageous become disadvantageous?

If the environment changes, the characteristic may no longer improve survival or reproduction

Biology Where Do We Come From? – What is the relationship between mutations and natural selection?

Mutations introduce new genetic variations, and natural selection can increase the frequency of advantageous mutations within a population

Biology Where Do We Come From? – What is the peppered moth example of natural selection?

During the Industrial Revolution, darker peppered moths became more common in polluted areas because they were better camouflaged against darkened tree surfaces

Biology Where Do We Come From? – Why did darker peppered moths have an advantage in polluted areas?

Dark moths were less visible to predators against soot-darkened surfaces, increasing their chances of survival and reproduction

Biology Where Do We Come From? – Why did lighter peppered moths become more common again in cleaner environments?

As pollution decreased and tree surfaces became lighter, lighter moths were better camouflaged and more likely to survive and reproduce

Biology Where Do We Come From? – What does the peppered moth example demonstrate?

Environmental changes can alter selection pressures, causing the frequency of inherited characteristics in a population to change over generations

Biology Where Do We Come From? – What are antibiotic-resistant bacteria?

Bacteria that have genetic variations allowing them to survive exposure to particular antibiotics

Biology Where Do We Come From? – How does antibiotic resistance develop through natural selection?

Random mutations may make some bacteria resistant, antibiotics kill susceptible bacteria, and resistant bacteria survive and reproduce, passing on resistance

Biology Where Do We Come From? – Do antibiotics cause bacteria to develop the specific mutations they need?

No, resistant mutations can occur randomly; antibiotics create a selection pressure that favours bacteria already carrying resistance

Biology Where Do We Come From? – Why can antibiotic resistance spread quickly through bacterial populations?

Bacteria reproduce rapidly, allowing resistant bacteria to multiply and pass on resistance genes

Biology Where Do We Come From? – How can antibiotic resistance be reduced?

Using antibiotics only when prescribed and appropriate, following medical instructions and reducing unnecessary antibiotic use

Biology Where Do We Come From? – What do peppered moths and antibiotic-resistant bacteria have in common?

Both demonstrate natural selection, where individuals with advantageous inherited variations survive and reproduce more successfully under particular environmental pressures

Biology Where Do We Come From? – How is evolution different from natural selection?

Evolution is the change in inherited characteristics of a population over generations, while natural selection is one mechanism that causes evolution

Biology Where Do We Come From? – How do fossils, DNA and homologous structures provide different evidence for evolution?

Fossils show changes in organisms over time, DNA reveals genetic relationships, and homologous structures suggest common ancestry

Biology Where Do We Come From? – Why is using multiple forms of evidence important when studying evolution?

Different forms of evidence support and strengthen scientific explanations, making conclusions about evolutionary relationships more reliable