4.4 Explaining Change- Variation & Evolution Flashcards
What can cause variation in an individual?
a combination of these
What is a mutation?
Change in DNA
What is a problem of selective breeding?
Inbreeding can occur
What is it called if two populations of one species become isolated geographically and evolve in different ways to suit different conditions?
Speciation
What is the definition of a species?
Organisms that can breed together to produce fertile offspring
Which is the correct order for classifying species?
Kingdom, Phyllum ,Class ,Order, Family, Genus, Species
Which of the following is not evidence for evolution?
Natural selection
Which two things does the binomial system use to name organisms?
Genus and species
Why is genetic engineering better than selective breeding?
Faster
Why does sexual reproduction produce a large amount of variation within a species?
Random mixing of genes from both parents
What is a mutation?
Changes in DNA
When can mutations be beneficial?
If the organism is more likely to survive because of the mutation
What is a variant?
Organisms that differ due to genetic mutations
Why would a mutation result in a possible change of phenotype?
If it occurs in DNA which is part of a gene
Explain why most mutations are not harmful.
They occur in parts of DNA that do not have a function
How common are mutations that affect phenotype?
Rare
How do mutations lead to a change in the phenotype?
Changes the sequence of amino acids and therefore the protein
How long ago did simple life forms first develop?
Over 3 billion years ago
What is meant by natural selection?
Variation in a species allowed some individuals to survive better than others
What evidence did Darwin use to suggest the theory of natural selection?
Differences in finches on the different Galapagos Islands, due to different food sources on each island
How do Darwin’s finches provide evidence for natural selection?
The finches were similar to, but not the same as, those on the mainland. They had changed over time
What is a species?
A group of organisms that can breed to produce fertile offspring
A mule is a cross between a horse and a donkey. Horses have 64 chromosomes, donkeys 62. Suggest why mules are infertile?
They have 63 chromosomes, which cannot be halved to produce gametes
What term describes when populations of organisms become new species?
Speciation
Suggest what could happen if a species cannot evolve?
It will go extinct
What are fossils?
Remains of dead organisms
Amber is fossilised tree resin. It is sometimes found containing preserved organisms. Why haven’t these decayed?
Lack of oxygen
Which part of an organism does mineral replacement most commonly happen to?
Bones and teeth
What is the evidence that tells us some organisms have changed very little over time?
There are fossils that look very similar to the organism as it is today
What is extinction?
When there are no more individuals of a species left alive
Why do we have few fossils of early life forms?
They were microbes or soft-bodied
How are relative ages of fossil species worked out?
By working out the age of the rock they are found in
Describe how antibiotic resistance develops.
A mutation causes the bacteria to be resistant to antibiotics, this bacteria survive and reproduce, passing on resistance
Suggest some other characteristics that sheep may be bred for apart from meat.
Wool, milk
Describe the technique of selective breeding.
Select organisms with desired characteristics, bred them together and repeat over many generations
Suggest two characteristics that a cattle farmer might want to develop.
Meat, milk production
Suggest 3 characteristics that crop plants could be bred for.
Increased yield, flavour, disease resistance
What could happen to a crop made up of one variety if the environment changed?
Could be wiped out
What are the disadvantages of selective breeding?
May reduce genetic fitness of individuals
What is inbreeding?
Production of offspring from mating individuals that are closely related genetically
How is a useful gene isolated from an organism’s genome?
Cutting it out using enzymes
How do scientists transfer an isolated gene into a target cell?
Using a vector
Give an example of a vector used in genetic engineering.
Virus or bacterial plasmid
What is a vector?
Something used to transfer genes
Why do bacteria make effective vectors?
They contain small loops of DNA which can be transferred to other cells
Give one useful substance that bacteria have been genetically modified to produce.
Insulin
Give two reasons for genetic modification of plant crops.
Increased yield, increased vitamin content
Give one benefit and one risk of GM crops.
Benefits – feeding the hungry, treating diseases
Risks – cross-pollination, resistant insects
What process is the gradual change in the inherited characteristics of a population over time?
Evolution
What is the classification system called where names are made up of genus + species?
The binomial system
How is selective breeding different from genetic engineering?
Selective breeding - process of breeding plants and animals with certain, desirable genetic features. Genetic engineering - transplanting genes for a desired characteristic into an organism
