Year 10 Biology- Evolution

What is evolution

the gradual change in the genetic material of a population of organisms over a period of time

What is evolutionary theory

the collection of scientific facts, observations and hypotheses that attempt to explain the diversity of life on the planet.

What is adaptation

characteristics of organisms that enhance their survival and reproduction in specific environments.

What is fossilisation

the process of an organism becoming a fossil

What is catastrophism

the principle that events in the past occurred suddenly and were caused by different mechanisms than those today.

What is natural selection

when the natural environment selects for or against a physical characteristic

What is biodiversity

the variety of living things on the earth such as plants, animals and microorganisms and the ecosystems they live in

What is a gene pool

a complete set of genes and alleles present in a reproducing population of organisms

What is allele frequency

How common an allele is within a population, affected by environmental factors

How do new alleles arise

through mutations- small changes in the dna sequence

What is selective pressure

the environmental factors that affect an organism's ability to survive

How does selective pressure work

causes individuals who are better suited to the environment to survive, who are able to produce offspring with the same traits, while organisms less suited to their environment are more likely to die off.

How does evolution relate to allele frequency

Evolution is the permanent change in the allelic frequencies within a population, caused by environmental changes.

What is a species

a group of organisms who are able to breed with each other to produce viable and fertile offspring

What is speciation

the formation of a new species through evolution that cannot reproduce with other species.

What is adaptation

a characteristic or behaviour of a species that allows it to survive and reproduce more effectively, and is favoured by environmental changes

What is survival of the fittest

when natural selection causes organisms best adapted to their environment to survive, while those with unfavorable adaptions will die

What is gene flow

the flow of genes from one generation to the next, or from one population to the next

What is isolation

the division of a population into two groups

What are selection pressures

environmental factors that affect an organism's ability to survive

What are examples of selection pressures

hunting by predators, access to resources like food, water and mating partners, environmental factors such as natural disasters and climate, vulnerability to disease, and human activity.

What is divergent evolution

where two species evolve to become more different over time due to different environments and selection pressures and becoming reproductively isolated

What is allopatric speciation

allopatric speciation is one of the most common ways species diverge. a population is separated by a permanent barrier such as a canyon, river or road, allowing mutations and selection pressures to completely change the allele frequency, leading to the populations becoming entirely different species

What is the result of allopatric speciation

entirely different species with homologous structures

What are homologous structures

characteristics that are common among species but used for different functions

What is an example of homologous structures

humans, bats, whales and monkeys all have similar bone structures in their hands, wings or flippers, but these structures are used for different functions. these animals have all evolved from a recent common ancestor

How does common ancestry affect homologous structures

species with a common ancestor should have homologous structures, as they evolved from the same species

What is convergent evolution

a process where unrelated organisms evolve to have similar characteristics as a result of adapting to similar environments with similar selection pressures

What is the result of convergent evolution

distantly related organisms that resemble each other and have characteristics with similar functions

What are analogous structures

characteristics of different species that have the same function but are structurally different

What is an example of analogous structures

a shark fin and a dolphin flipper resemble each other physically and are used for the same function, but are structurally different, as a shark fin is made of cartliage and a dolphin flipper has a bone structure. these animals have adapted to similar environments in similar ways without a common ancestor, developing characteristics with the same function but that are structurally different

What is a fossil

the remains or traces of organisms from the past embedded into rocks or other substances

What do fossils provide

fossils provide a record of the history of life on earth, and are the most powerful evidence of evolution

What is a trace fossil

a fossil which is not a part of an organism but leaves a trace of that organism, such as imprints of leaves, footprints and fecal fossils.

What is a living fossil

a fossil of an existing species that has remained unchanged for millions of years

What is a transitional fossil

a fossil of an organism that shows an intermediate state between an ancestral form and its descendant, which becomes a 'missing link' between species

What is relative age

the age of an object in relation to the ages of other objects in layers of rock or strata

What is absolute age

the actual age of an object in years

How is absolute age determined

absolute age is determined through radioactive dating processes in which the half-life in radioactivity of an object is measured

What is biogeography

the study of the locations of organisms around the world, referring to the distribution of plants and animals in the earth's various regions

What is the theory of continental drift

the theory of continental drift explains how continents were once connected in a single land mass, and over time split up into separate land masses which drifted away from each other.

What was the first single land mass

pangea

What were the two land masses which pangea split into

laurasia, the northern land mass, and gondwana, the southern land mass

How is the theory of continental drift supported

this theory is supported by identical fossils buried on land masses which were once joined together, and supports the idea of geographical isolation of species resulting in divergent evolution

What are vestigal organs

a structure in an organism that no longer has an obvious purpose, and seems to be left over from a previous ancestor as historical remnants of an important organ

What are some examples of vestigial organs in humans

the appendix, third molars or wisdom teeth, and a tail bone

How has the appendix become a vestigial structure

early humans had a large organ called a cecum which was used to break down tough plant fibres. as cooking became more common and humans relied less on digesting raw plant cellulose, the cecum structure became smaller, leaving behind the appendix.

How has the third molars or wisdom teeth become a vestigial structure

early humans had very large jaws for tougher diets, as extra molars grinded down tough plant fibres. as humans evolved and their diet changed, modern humans developed smaller jaws, so the third molars are not needed for survival and often become impacted

How do vestigial structures show relationships to ancestors

vestigial structures show relationships to organisms which lived in the past as existing species show evidence of structures which were very important to ancient species, showing how current organisms have evolved from ancient organisms.

How does the human tailbone show a connection to an ancient ancestor

the human tailbone is made up of 4 vertebrae fused together, which resembles an animal's tail. this provides evidence that humans have evolved from ancient species that required a tail to survive

What is embryology

the stufy of embryos and their development

How does embryology link organisms with common ancestors

organisms which shared a common ancestor will show similarities during embryo development, and develop similar structures, providing evidence that these organisms have all evolved from the same ancient species

How does comparing DNA allow for comparison between species

comparing the order of nucleotides in dna allow species to be compared. the more similar the dna strands from each organism are, the more closely related the two species are, while the more differences in order of nucleotides show that more time has passed since a common ancestor

What is phylogenetic tree

a branching tree-like diagram showing relationships between different groups of organisms

Why should organisms not only be compared by physical traits

while species may look similar, their internal structures may be very different and may not share common ancestry or be closely related, but instead share common characteristics as a result of convergent evolution

What is selective breeding?

the intentional breeding of two organisms for desirable traits

What is an example of selective breeding?

the selective breeding of domesticated dogs for desirable traits and mixes between breeds