Natural Selection and Genetic Modification

Yep — Topic 4: Natural Selection and Genetic Modification. I've kept it in the same Knowt-importable format and covered every point 4.1B–4.14, including the maths skills.

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Who were Charles Darwin and Alfred Wallace?

Scientists who independently developed the theory of evolution by natural selection.

What did Darwin and Wallace propose?

They proposed that species change over time through natural selection acting on inherited variation.

Why was Darwin and Wallace's work important to modern biology?

It provided the foundation for understanding evolution and how populations change over generations.

What is evolution?

The change in the inherited characteristics of a population over generations.

What is natural selection?

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

What was Darwin's theory of evolution by natural selection based on?

Variation exists within populations, organisms compete for resources, individuals with advantageous characteristics are more likely to survive and reproduce, and these characteristics become more common over generations.

Why is there competition between organisms?

Resources such as food, water, space and mates are limited.

What happens to organisms with advantageous inherited characteristics?

They are more likely to survive and reproduce.

What happens to advantageous alleles over many generations?

They become more common in the population.

How does natural selection cause evolution?

Individuals with advantageous inherited characteristics reproduce more successfully, so the alleles responsible become more common over generations.

What is an adaptation?

A characteristic that increases an organism's ability to survive and reproduce in its environment.

What is an example of natural selection?

A population of bacteria contains variation in antibiotic resistance; resistant bacteria survive antibiotic treatment and reproduce, increasing resistance in the population.

How does antibiotic resistance support Darwin's theory?

Bacteria with mutations giving antibiotic resistance survive treatment and reproduce, so resistant bacteria become more common.

Why does antibiotic resistance develop in bacterial populations?

Random mutations can produce resistance, and antibiotics select for resistant bacteria by killing susceptible bacteria.

Do antibiotics cause bacteria to mutate specifically to become resistant?

No. Random mutations occur first, and antibiotic use selects for bacteria that already have resistance.

Why is antibiotic resistance a problem?

It can make bacterial infections harder to treat because antibiotics may no longer kill the resistant bacteria.

What is a fossil?

The preserved remains or traces of an organism from the past.

How can fossils provide evidence for human evolution?

They show changes in human anatomy over time and allow scientists to compare ancient species with later humans.

What is Ardi?

A fossil hominin specimen dating from about 4.4 million years ago that provides evidence about early human evolution.

How old is Ardi?

About 4.4 million years old.

What is Lucy?

A famous Australopithecus afarensis fossil dating from about 3.2 million years ago.

How old is Lucy?

About 3.2 million years old.

What did Richard Leakey discover that provides evidence for human evolution?

Fossils dating from about 1.6 million years ago.

How old are the fossils associated with Richard Leakey's discovery required by the specification?

About 1.6 million years old.

What can comparisons between fossils from different periods show?

Changes in anatomical features over time, providing evidence for human evolution.

Why are fossils useful but incomplete evidence for evolution?

Fossilisation is rare, so the fossil record does not contain every organism that lived in the past.

How do stone tools provide evidence for human evolution?

Changes in the design and complexity of stone tools over time provide evidence of changes in human behaviour and abilities.

How did stone tools develop over time?

Early simple tools became more complex and specialised over time.

Why can stone tools be used to study human evolution?

Their increasing complexity provides evidence of changes in human technology and behaviour.

How can stone tools be dated?

They can be dated using evidence from the geological layers and materials in the environment where they were found.

What is a pentadactyl limb?

A limb with five digits.

Why does the pentadactyl limb provide evidence for evolution?

Different vertebrates have the same basic bone structure despite their limbs being adapted for different functions, suggesting they evolved from a common ancestor.

What does homologous structure mean?

A structure with a similar underlying anatomy found in different organisms, often adapted for different functions.

Why are pentadactyl limbs described as homologous structures?

They have the same basic arrangement of bones but are adapted for different functions such as walking, swimming or flying.

What are the three domains of life?

Bacteria, Archaea and Eukarya.

What was the traditional five-kingdom classification based largely on?

Observable characteristics and cell structures.

How did genetic analysis change biological classification?

Comparing DNA and RNA sequences revealed evolutionary relationships that led scientists to propose three domains rather than five kingdoms.

What is the Eukarya domain?

The domain containing organisms whose cells have a nucleus, including animals, plants, fungi and protists.

What is selective breeding?

The process of choosing organisms with desirable characteristics and breeding them so their offspring are more likely to have those characteristics.

What are the main stages of selective breeding?

Choose parents with desirable characteristics, breed them, select offspring with the desired characteristics, and repeat the process over many generations.

How has selective breeding affected food plants?

It has produced crop varieties with desirable characteristics such as higher yield, larger fruits or disease resistance.

How has selective breeding affected domesticated animals?

It has produced animals with desirable characteristics such as increased milk production, meat production or particular physical traits.

What is an advantage of selective breeding?

It can increase the frequency of desirable characteristics in a population.

What is a disadvantage of selective breeding?

It can reduce genetic variation and increase the risk of inherited genetic disorders.

What is tissue culture?

A technique in which small pieces of plant or animal tissue are grown under controlled conditions to produce cells or organisms.

How is tissue culture used in plant breeding?

Small pieces of plant tissue can be grown to produce many genetically identical plants with desirable characteristics.

What are advantages of tissue culture in plant breeding?

It allows rapid production of large numbers of genetically identical plants with desirable characteristics and can produce disease-free plants.

How can tissue culture be useful in medical research?

It allows cells or tissues to be grown under controlled conditions so scientists can study diseases, test treatments and investigate cell behaviour.

Why is tissue culture useful for producing plants quickly?

Many plants can be produced from a small amount of starting tissue in a relatively short time.

What is genetic engineering?

The process of modifying an organism's genome to introduce desirable characteristics.

What is the purpose of genetic engineering?

To introduce a gene or alter genetic material so an organism gains a desired characteristic.

What are the main stages of genetic engineering?

Identify and isolate the desired gene, cut the DNA using restriction enzymes, insert the gene into a vector using ligase, and transfer the vector into the target organism.

What are restriction enzymes?

Enzymes that cut DNA at specific base sequences.

What is the role of restriction enzymes in genetic engineering?

They cut out the desired gene and cut the vector DNA at suitable locations.

What are sticky ends?

Short sections of single-stranded DNA created when restriction enzymes cut DNA in a staggered way.

Why are sticky ends useful in genetic engineering?

Complementary sticky ends allow the desired gene to attach to the cut vector DNA.

What is DNA ligase?

An enzyme that joins DNA fragments together.

What is the role of ligase in genetic engineering?

It joins the desired gene to the vector DNA by forming bonds between the DNA fragments.

What is a vector in genetic engineering?

A carrier used to transfer a gene into a target cell.

What can be used as a vector?

Plasmids, viruses or other suitable DNA carriers.

What is a plasmid?

A small circular piece of DNA commonly found in bacteria that can be used as a vector.

How can a gene be inserted into a plasmid?

The plasmid and desired gene are cut with the same restriction enzyme, allowing complementary sticky ends to join, and DNA ligase joins them together.

What is a GM organism?

An organism whose genetic material has been genetically modified using genetic engineering.

What is a GM crop?

A crop plant whose genome has been genetically modified to introduce a desirable characteristic.

What is an advantage of GM crops?

They can be modified to increase yield or improve resistance to pests, disease or environmental conditions.

What is an advantage of GM crops with insect resistance?

They can reduce damage caused by insect pests and may reduce the need for chemical insecticides.

What is Bacillus thuringiensis?

A bacterium that produces a toxin that is harmful to certain insect pests.

How can genes from Bacillus thuringiensis be used in GM crops?

The gene coding for an insecticidal toxin can be inserted into crop plants so the plants produce the toxin and become resistant to certain insects.

What is an advantage of Bt insect-resistant crops?

They can reduce crop losses caused by insect pests.

What is another possible advantage of insect-resistant GM crops?

They may reduce the use of chemical insecticides.

What is a disadvantage of GM crops?

There may be concerns about effects on non-target organisms and ecosystems.

What is another potential disadvantage of GM crops?

Genes could potentially spread to wild relatives through cross-pollination.

Why can GM crops raise ethical concerns?

Some people have concerns about altering organisms' genomes and the long-term effects of releasing GM organisms into the environment.

What is a potential economic concern of GM crops?

Farmers may become dependent on particular companies or patented GM seeds.

What are agricultural solutions to the demands of a growing human population?

Methods such as fertilisers, selective breeding, genetic engineering and biological control can increase food production.

Why are fertilisers used in agriculture?

To provide mineral ions needed for plant growth and increase crop yield.

What is an advantage of using fertilisers?

They can increase plant growth and crop yields.

What is a disadvantage of excessive fertiliser use?

It can cause eutrophication when nutrients enter waterways.

What is biological control?

Using one organism to control the population of another organism, usually a pest.

What is an advantage of biological control?

It can reduce pest populations without relying entirely on chemical pesticides.

What is a disadvantage of biological control?

The introduced control organism may affect non-target species or become invasive.

Why must biological control be carefully managed?

The introduced organism may disrupt ecosystems or cause unexpected environmental effects.

How can genetic engineering help agriculture?

It can introduce characteristics such as insect resistance, disease resistance or improved nutritional content.

How can selective breeding help agriculture?

It can increase the frequency of desirable characteristics such as higher yield, disease resistance or improved quality.

What are potential medical benefits of genetic engineering?

It can be used to produce useful medicines, hormones and other therapeutic proteins.

How can genetic engineering be used to produce insulin?

A human insulin gene can be inserted into microorganisms, which then produce human insulin.

What is one ethical concern about genetic engineering?

There are concerns about changing organisms' genetic material and the possible consequences of doing so.

What is one practical concern about genetic engineering?

The effects of releasing genetically modified organisms into ecosystems may be difficult to predict or control.

What is selective breeding's main limitation compared with genetic engineering?

Selective breeding relies on existing variation and can take many generations, whereas genetic engineering can introduce a specific gene directly.

What is one risk of selective breeding?

Repeated breeding of closely related organisms can reduce genetic diversity and increase inherited disorders.

What is one benefit of selective breeding in medicine?

It can be used to produce organisms with characteristics useful for medical research or production of medicines.

What should be considered when evaluating genetic engineering in agriculture?

Benefits such as increased yield and pest resistance should be weighed against environmental, economic and ethical risks.

What should be considered when evaluating selective breeding?

Its benefits in producing desirable characteristics should be weighed against reduced genetic variation and potential inherited disorders.

What should be considered when evaluating agricultural technologies?

Both practical effectiveness and ethical, environmental and economic implications.

What does it mean to translate information between numerical and graphical forms?

Converting information between numbers, tables, graphs and other graphical representations.