Variation and Evolution

• What are the three main causes of variation in a population?

  Genetic causes, environmental causes, and combinations
• What is meant by variation in biology?

  Differences in characteristics of individuals
• How does the environment cause variation in flowers?


  The color depends on the pH of the soil
• What must a person's diet include for their height to fully develop?

  Enough calcium for bone development
• What is the source of genetic variation in a population?

  Mutations in DNA
• What are mutations?

  Random changes to DNA
• How often do mutations occur?

  All the time
• What is the effect of most mutations on the phenotype?

  Most have no effect at all
• How can some mutations influence the phenotype?

  By leading to traits like tallness
• What is a key idea about mutations and phenotypes?

  Very rarely can lead to a new phenotype
• What can a beneficial new phenotype lead to?

  A rapid change in the species
• What happened to the wild rabbit population in the UK in the 1950s?

  A virus reduced the population significantly
• What mutation occurred in the wild rabbits?

  Some became resistant to the virus
• What is the result of the beneficial mutation in rabbits?

  A new phenotype widespread in the population
• How does evolution take place according to the video?

  Through natural selection
• How many different species of animals and plants are there on Earth?

  Nearly 9 million
• What percentage of species that have ever lived on Earth are currently alive?

  One percent
• How long ago did life first develop on Earth?

  More than 3 billion years ago
• What were the first life-forms on Earth described as?

  Very simple, like single cells
• What is the process called where all species of living things have evolved from simple life forms?

  Evolution by natural selection
• What do rabbits inherit from their parents?

  A combination of alleles
• What advantage do rabbits with thicker fur have in a colder environment?

  They are more likely to survive
• What happens to the alleles for thicker fur over many generations?

  They become more common in the population
• What advantage do rabbits with better eyesight or hearing have when a predator moves in?

  They can detect the predator sooner
• What is the definition of evolution provided in the video?

  Change in inherited characteristics over time
• What can happen when two populations of one species become very different?

  They can no longer interbreed
• Why can't pygmy rabbits breed successfully with normal-sized rabbits?

  They are too different in phenotype
• What is the impact of environmental changes on species?

  It can lead to natural selection
• What is speciation?

  Formation of new species from populations
• What is another term for selective breeding?

  Artificial selection
• What is one impact of selective breeding on food plants?

  It affects domesticated animals
• What is a disadvantage of selective breeding?

  It can lead to inbreeding
• What type of animals are wolves?

  Wild animals
• How did humans utilize wolves thousands of years ago?

  For protection and companionship
• What process was used to produce modern dogs from wolves?

  Selective breeding
• What is the first step in selective breeding for larger cows?

  Select the largest male and female
• What does sexual reproduction produce in the offspring during selective breeding?

  Variation in the offspring
• What do you do with the largest male and female offspring in selective breeding?

  Breed them together
• How long does selective breeding continue?

  Over many generations
• What is a major problem with inbreeding in selective breeding?

  It can cause inherited defects