Evolution

Who was Charles Darwin?

A naturalist who developed the theory of evolution by natural selection.

What did Darwin observe on the Galápagos Islands?

Different species, including finches, had adaptations suited to their environments.(natural selection)like they couldnt fly far bc they didnt need to bc they wernt hunted

What was Darwin’s book called?

On the Origin of Species, published in 1859.

What is evolution?

The change in inherited characteristics of populations over many generations.

What is natural selection?

Individuals with beneficial inherited traits are more likely to survive and reproduce.

What is survival of the fittest?

Individuals best suited to their environment tend to reproduce more successfully.

What does fitness mean in evolution?

How successfully an organism survives and produces offspring in its environment.

What are the four main steps of natural selection?

Variation, competition, differential survival and reproduction, and inheritance.

What is variation?

Differences in characteristics between species

What is genetic variation?

Differences in DNA and alleles (specific veriants of dna) between individuals.

What is environmental variation?

Differences caused by environmental factors, such as diet or sunlight.

What causes genetic variation?

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

What is a mutation?

A change in DNA that can create a new allele.

What is an adaptation?

An inherited feature that helps an organism survive and reproduce.

How do adaptations affect evolution?

Beneficial inherited adaptations can become more common over generations.

Give an example of a structural adaptation.

A polar bear’s thick fur helps insulate it in cold environments.

Give an example of a behavioural adaptation.

Bird migration helps some birds find food and suitable breeding areas.

Give an example of a physiological adaptation.

A camel’s kidneys conserve water in dry environments.

Give an example of natural selection.

Antibiotic-resistant bacteria survive treatment and reproduce, making resistance more common.

How did Darwin’s finches demonstrate natural selection?

Different beak shapes helped finches use different food sources.

How does natural selection change a population?

Beneficial inherited traits become more common over generations.

Do individual organisms evolve during their lifetime?

No. Populations evolve over generations. Individuals can grow or acclimatise.

Who was Jean-Baptiste Lamarck?

A scientist who proposed that acquired characteristics could be inherited

What did Lamarck believe about evolution?

He thought use and disuse changed traits and acquired changes could be passed to offspring.

Who was Alfred Russel Wallace?

A naturalist who independently developed the idea of evolution by natural selection.

How did Wallace contribute to Darwin’s theory?

How did Wallace contribute to Darwin’s theory? His similar ideas encouraged Darwin to publish his work on natural selection.

Who was Charles Lyell?

A geologist whose work supported the idea that Earth was very old and changed over time.

What did Thomas Malthus influence Darwin to consider?

Populations produce more offspring than resources can support, causing competition.

What is speciation?

The formation of new species from existing populations.

How can geographic isolation cause speciation?

A barrier separates populations, which evolve independently until they become reproductively isolated.

What is reproductive isolation?

When populations can no longer successfully interbreed to produce fertile offspring.

What is a species?

A group of organisms that can usually interbreed and produce fertile offspring.

What is a homologous structure?

A structure with a similar underlying anatomy due to common ancestry, possibly with different functions.

Give an example of homologous structures.

Human arms, whale flippers and bat wings share a similar basic bone arrangement.

What is an analogous structure?

A structure with a similar function but a different evolutionary origin.

Give an example of analogous structures.

Bird wings and insect wings both enable flight but evolved differently.

What is comparative embryology?

Comparing embryos of different species to identify similarities that may indicate common ancestry.

How does embryology provide evidence for evolution?

Similar early developmental features can suggest that species share a common ancestor.

What is biogeography?

The study of where organisms live and how they are distributed across Earth.

How does biogeography support evolution?

Species in nearby regions or isolated locations can show patterns explained by common ancestry and adaptation.

What is a vestigial structure?

An inherited structure that has lost most or all of its original ancestral function.

Give an example of a vestigial structure.

The human tailbone is a remnant of structures associated with ancestral tails.

What are the main types of evidence for evolution?

Fossils, comparative anatomy, embryology, biogeography, vestigial structures and molecular evidence.

How do fossils support evolution?

They show organisms from the past and changes in life forms over time. they show transition

What is DNA?

The molecule that stores hereditary genetic information in living organisms.

How does DNA provide evidence for evolution?

More similar DNA sequences generally indicate a more recent common ancestor.

What is RNA?

A nucleic acid involved in using genetic information to make proteins and in other cellular functions.

How can RNA support evolutionary relationships?

Comparing RNA sequences can reveal similarities and differences between organisms.

What is a gene?

A section of DNA that contains instructions for a functional product, such as a protein.

What is an allele?

a different version of the same gene (A gene is the instruction, and an allele is a version of that instruction.)

What is a cladogram?

A branching diagram showing hypothesised evolutionary relationships based on shared characteristics.

What does a branch point on a cladogram represent?

A common ancestor where evolutionary lineages diverged.

What is a derived characteristic?

A trait that evolved in a lineage and can help identify related group

A trait that evolved in a lineage and can help identify related groups.

Find branch points and compare how recently groups share a common ancestor.

Which organisms are most closely related on a cladogram?

The organisms that share the most recent common ancestor.

Does a cladogram show which organism is more evolved?

No. Modern species have all been evolving for the same amount of time since their shared ancestors.

What does a shared derived characteristic suggest?

The organisms sharing it may belong to a group descended from a common ancestor.

Why is DNA useful alongside cladograms?

DNA comparisons help scientists test and refine hypotheses about evolutionary relationships.