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Mapa Mental por stella watkins, actualizado hace más de 1 año
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Creado por stella watkins
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Evolution
- Darwin
- • Darwin’s theory of evolution by natural selection states that all species of living things have evolved
from simple life forms that first developed more than three billion years ago.
- • These first organisms were very simple single-celled organisms, similar to bacteria.
- • The theory of evolution by natural selection was only gradually accepted because:
- the theory challenged the idea that God made all the animals and plants that live on Earth
- there was insufficient evidence at the time the theory was published to convince many scientists
- the mechanism of inheritance and variation was not known until 50 years after the theory was
published.
- the mechanism of inheritance and variation was not known until 50 years after the theory was
published.
- there was insufficient evidence at the time the theory was published to convince many scientists
- the theory challenged the idea that God made all the animals and plants that live on Earth
- Natural Selection
- • Organisms produce large numbers of offspring
- • Individual organisms within a particular species may show a wide range of variation because of
differences in their genes
- • There is a struggle for all organisms to exist (eg. Predation)
- • Individuals with characteristics most suited to the environment are more likely to survive to breed
successfully
- The genes which have enabled these individuals to survive are then passed on to the next generation
- • Gradually, this can result in changes in the characteristics of a species.
- • Gradually, this can result in changes in the characteristics of a species.
- The genes which have enabled these individuals to survive are then passed on to the next generation
- • Individuals with characteristics most suited to the environment are more likely to survive to breed
successfully
- • There is a struggle for all organisms to exist (eg. Predation)
- • Individual organisms within a particular species may show a wide range of variation because of
differences in their genes
- • Organisms produce large numbers of offspring
- • Darwin’s theory of evolution by natural selection states that all species of living things have evolved
from simple life forms that first developed more than three billion years ago.
- Lamarck
- • He proposed a theory of acquired characteristics.
- • He argued that an individual’s characteristics will change over its lifetime due to amount of use.
- • Eg. Giraffes necks get longer due to stretching for leaves.
- • Eg. Giraffes necks get longer due to stretching for leaves.
- • Then he suggested that these characteristics could be inherited.
- We now know that in the vast majority of cases this type of
reproduction cannot occur. • Changes in the body do not change the
genes.
- • He proposed a theory of acquired characteristics.
- Classification
- • Studying the similarities and differences between organisms allows us to classify living organisms
into animals, plants and microorganisms.
- • This helps us to understand evolutionary and ecological relationships
- • Evolutionary trees (models) are used to represent the relationships between organisms.
- This tree indicates how long ago the ancestors of ape species diverged from each other. It
indicates that humans share a common ancestor with chimpanzees more recently than with any
other ape species.
- • Studying the similarities and differences between organisms allows us to classify living organisms
into animals, plants and microorganisms.
- Mutations
- • How do mutations occur?
- • Errors occur when the DNA is replicated prior to cell division.
- • Errors may occur when chromosomes are separated during cell division.
- • Errors may occur when chromosomes are separated during cell division.
- • Errors occur when the DNA is replicated prior to cell division.
- • What do mutations do?
- • Genes control the synthesis of proteins.
- • Therefore a change in a gene or a new sequence of genes can result in different proteins being
synthesised.
- • This can change a characteristic.
- • This can change a characteristic.
- • Therefore a change in a gene or a new sequence of genes can result in different proteins being
synthesised.
- • Genes control the synthesis of proteins.
- • Most mutations are harmful or fatal.
- • How do mutations occur?
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