Variation, inheritance and evolution

Question 1

what is evolution

Answer 1

a change in the inherited characteristics of a population overtime through the process of natural selection which may result in the formation of a new species

Question 2

theory of evolution

Answer 2

all species of living things have evolved from simple life forms that first developed more than 3 billion years ago

Question 3

what is a species

Answer 3

a group of organisms with similar features that can reproduce with eachother and produce a fertile offspring

Question 4

natural selection theory

Answer 4

• Variation exists in a population due to mutation. some have… some have no….
• some alleles are advantageous and means that an individual is more likely to survive
• surviving individuals are more likely to reproduce and pass their advantageous allele onto offspring
• this process repeats over many generations and eventually the allele is more frequent in the population

Question 5

why Darwin’s theory took a long time to be accepted

Answer 5

• challenged creationism theory ( god made all animals on earth)
• insufficient evidence
• genes not discovered until 50 years later

Question 6

why evolution is easier to study in birds

Answer 6

• lifespan is much shorter than humans so many generations of birds can be studied
• can produce lots of offspring, so there are more to study. humans can only produce one offspring per year
• effects of mutation seen sooner
• genetics of population change faster
• humans can see evolution in birds, within a human lifespan

Question 7

what is extinction

Answer 7

The permanent loss of all the members of a species, caused by a change in the environment of the organism

Question 8

causes of extinction

Answer 8

• new predators
• environmental changes e.g. global warming, drought
• new infections and diseases
• single catastrophic event such as a volcanic eruption
• new competition (animals) e.g. grey squirrels introduced in the UK

Question 9

theory of speciation

Answer 9

• there is variation in the original population due to mutation
• the population becomes separated by a geographical barrier
• the populations are isolated and experience different environments
• different alleles are advantageous in each environment and are selected for
• if populations meet again they can no longer produce fertile offspring and have become a different species

Question 10

what is classification

Answer 10

the organisation of living things into groups according to their similarities

Question 11

what can organisms be classified based on

Answer 11

• evolutionary relationships
• genetic similarities (DNA)
• biochemical similarities
• embryonic similarities

Question 12

evidence for evolution by natural selection

Answer 12

fossils and bacteria

Question 13

antibiotic resistance in bacteria

Answer 13

Bacteria reproduce by binary fission at a very fast rate, meaning that they can evolve rapidly. mutations have given rise to some bacterial strains that are resistant to particular antibiotics

A population of bacteria in the gut - some have antibiotic resistance. when exposed to an antibiotic, bacteria causing illness aswell as healthy gut bacteria are killed. remaining bacteria are the resistant ones who reproduce

Question 14

prevention of antibiotic resistant bacteria

Answer 14

• not overusing antibiotics
• finishing a full course of antibiotics to ensure bacteria are killed
• farming methods should be modified so animals aren’t routinely given antibiotics to prevent illness

new antibiotics are costly and may not keep up with the emergence of new resistant strains

Question 15

what are fossils

Answer 15

remains of organisms from millions of years ago that have been preserved in rock, ice or other substances

Question 16

what is interdependence

Answer 16

organisms depending on eachother for survival