bio natural selection

What is natural selection? The process where organisms with characteristics best suited to their environment are more likely to survive and reproduce, passing on their advantageous traits to the next generation. This is also known as survival of the fittest.

What are the main steps of evolution by natural selection?

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Variation exists within a population as a result of genetic mutations.

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Organisms with characteristics most suited to the environment are more likely to survive and breed successfully.

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The beneficial characteristics are then passed on to the next generation.

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Over many generations, the frequency of alleles for this advantageous characteristic increase within the population.

Who were the key scientists involved in developing the theory of evolution by natural selection? Charles Darwin and Alfred Russel Wallace. Darwin published ‘On the Origin of Species’. Wallace also developed the theory of speciation.

What types of evidence support the theory of evolution?

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Fossil evidence shows how organisms developed slowly over time. Examples include Ardi, an early human ancestor with both ape and human-like features, and Lucy, who had a human-like upright walking posture but a chimp-like skull. The dating of fossils using carbon dating helps understand the timeline of evolution.

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Dating of stone tools found with fossils indicates the development of cognitive abilities over time. More complex tools appeared with more evolved human species.

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Anatomical evidence, such as the pentadactyl limb found in diverse animals like humans, bats, and birds, suggests a common ancestor.

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Emerging resistance in bacteria to antibiotics demonstrates natural selection in action. Bacteria with resistance survive and reproduce, increasing the frequency of the resistance gene in the population.

Explain the process of speciation.

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Variation exists within a population due to genetic mutations.

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Alleles which provide a survival advantage are selected for through natural selection.

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Populations of a species can become isolated, preventing them from breeding together.

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Different alleles may be advantageous in the new environment, leading to them being selected for.

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Over time the selection of different alleles will increase the genetic variation between the two populations.

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When they are no longer able to breed together to produce fertile offspring, a new species has formed.

What is selective breeding? A process where humans choose which organisms to breed in order to produce offspring with certain desirable characteristics. This can lead to a reduction in the gene pool and inbreeding.

What is tissue culture? A method of culturing living tissue outside the organism, within a growth medium. In plants, this can be used to produce identical cloned crops from a small cutting.

What is genetic engineering? Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic. This involves using restriction enzymes to cut out genes and inserting them into a vector like a plasmid, using ligase enzyme to join them.

Give some examples of the applications of genetic engineering.

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Creating disease-resistant crops.

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Producing crops with larger fruits.

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Engineering bacteria to produce substances like human insulin.

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Developing Bt crops that produce toxins to kill insect larvae.

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Potential for gene therapy to treat inherited disorders.

What are some concerns associated with genetic engineering?

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Potential negative effects on wild flowers and insects.

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The possibility of genes spreading to wild plants, leading to infertility.

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Growing GM crops with herbicides and pesticides can reduce biodiversity.

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Uncertainties about the long-term effects on human health.

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The development of super weeds and pests with increased resistance.

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Ethical concerns about the potential for genetic engineering in humans and "designer babies".

Explain the development of antibiotic resistance in bacteria.

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Mutations during reproduction can result in new genes, such as the gene for antibiotic resistance.

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Exposure to antibiotics creates a selection pressure; bacteria with resistance survive, while those without die.

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Resistant bacteria reproduce and pass on the advantageous gene, increasing the population of antibiotic-resistant bacteria.

What are the Five Kingdoms and Three Domains systems of classification?

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Five Kingdoms: Animals, Plants, Fungi, Prokaryotes, Protists. Classification was based on visible traits.

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Three Domains: Archaea, Bacteria, Eukaryota. This system is based on genetic analysis, such as RNA sequence analysis.

What is a pentadactyl limb and what does it suggest about evolution? A limb with five digits found in many different animals. Its presence suggests that these animals share a common ancestor, and the limb has adapted for different functions due to different selection pressures in various environments


What was Alfred Russel Wallace's contribution to the theory of evolution? Alfred Russel Wallace developed the theory of speciation and, independently, the concept of evolution by natural selection1. He also recognized that individuals lacking advantageous characteristics for their environment would die out1. He published joint studies with Darwin1.

Why was there controversy surrounding Darwin's theory of evolution? Darwin's ideas faced controversy because they contradicted the religious belief that God created all species2. Additionally, there was limited evidence and understanding of inheritance and variation at the time2.

What is significant about the fossil "Ardi"? "Ardi" (Ardipithecus ramidus) is the oldest known human ancestor, estimated to have lived 4.4 million years ago3. Its fossil exhibits humanoid features alongside ape-like characteristics, representing an intermediate form and supporting gradual evolution3. Its bone structure suggests that humans and chimpanzees evolved separately3.

What is significant about the fossil "Lucy"? "Lucy" is a fossil dating back 3.2 million years ago4. Her bone structure indicates she walked in an upright, human-like position, but she had a small, chimp-like skull and brain, representing another intermediate stage between apes and early humans4.

What did Louis and Mary Leakey discover that supported the theory of natural selection? Louis and Mary Leakey discovered fossils, including those with remnants of stone tools, suggesting early toolmakers, and Homo habilis, considered an important early human species4.

How can we date stone tools? Stone tools can be dated using radiometric carbon dating of any once-living material found with the tool (like wood or fur) or by stratifying rock layers, assuming that objects within the same sediment layer are of a similar age5.

What are the problems associated with selective breeding? Selective breeding can lead to inbreeding, which reduces the gene pool6. This makes the population more vulnerable to new diseases or environmental changes6. It also increases the likelihood of genetic defects appearing in offspring7.

What are the benefits and risks of tissue culture in plants? Benefits: It can produce lots of offspring with specific desirable features and can increase the number of crops resistant to bad weather, potentially increasing crop yields8.... Risks: It reduces the gene pool due to the production of clones, making the population less likely to survive diseases8. Clones may also have a low survival rate and genetic problems9.

What role do restriction enzymes and ligase play in genetic engineering? Restriction enzymes are used to cut out the desired gene from the source organism's DNA and to cut open the vector (e.g., a plasmid)9. Ligase enzyme is then used to join the gene and the vector together, creating recombinant DNA9.

What are some advantages of genetically modified (GM) crops? GM crops can be engineered to be resistant to insects and herbicides, leading to increased yields10.... They can also be modified to have improved nutritional content, like extra vitamins, and to grow in different conditions12....

What are some disadvantages of genetically modified (GM) crops? There are concerns about the potential effects on wild flowers and insects, the possibility of genes spreading to wild plants and causing infertility, and the potential for increased resistance in other species, leading to super weeds and pests14.... There are also worries about the unknown effects on human health11....

How does antibiotic resistance in bacteria support Darwin's theory of natural selection? The emergence of antibiotic-resistant bacteria demonstrates natural selection because the antibiotics act as a selection pressure, killing non-resistant bacteria while those with resistance survive and reproduce, passing on the advantageous resistance gene19.... This leads to an increase in the frequency of resistant bacteria in the population20.

What is the difference between the Five Kingdoms and Three Domains systems of classification? The Five Kingdoms system classifies organisms into Animals, Plants, Fungi, Prokaryotes, and Protists based on visible traits21. The newer Three Domains system (Archaea, Bacteria, Eukaryota) is based on genetic analysis, revealing more accurate evolutionary relationships22.

Why is the pentadactyl limb considered evidence for evolution? The pentadactyl limb, a limb with five digits found in various animals with different functions, suggests that these diverse species share a common ancestor. Over time, due to different selection pressures, this basic limb structure has been adapted for different uses, such as grasping, flying, and swimming23.