Speciation and Evolution

Question 1

What is a species

Answer 1

a group of organisms that are genetically very similar and can reproduce to give fertile offspring

Question 2

What 2 types of isolation can result in speciation

Answer 2

reproductive isolation or geographic isolation

Question 3

what is speciation

Answer 3

the change in an organism overtime that results in the formation of a new species

Question 4

Describe isolation

Answer 4

• two populations of a species can become geographically separated because of the environment
• isolation can prevent interbreeding and the combination of genes within a species
• different mutations can take place in the isolated groups and create different
  phenotypes within a particular location
• over time species may evolve to be different to each other, and they will not be able to interbreed

Question 5

New species can arise from

Answer 5

• genetic variation - each population has a wide range of alleles that can control their characteristics
• natural selection
• the alleles which help an organism to survive are selected in each population
• speciation - the populations become extremely varied and successful interbreeding cannot happen anymore

Question 6

Charles Darwin described the speciation of finches after his studies of the birds on the Galapágos Islands. What did he notice?

Answer 6

The finches on different islands looked similar to each other but had variations in their beaks, claws and size.

The finches’ beaks differed depending on the local food source. Darwin concluded that because the islands were distant from the mainland, the finches that had arrived there had changed over time.

Question 7

Definition of a fossil

Answer 7

A fossil is the preserved remains of a dead
organism from millions of years ago

Question 8

Definition of extinction

Answer 8

the disappearance of a species, either globally or locally

Question 9

Fossils are found in rocks and can be formed from…

Answer 9

• hard body parts, such as bones and shells, which do not decay easily or are replaced by minerals as they decay
• parts of organisms that have not decayed because one or more of the conditions needed for decay are absent. For example, dead animals and plants can be preserved in
  amber, peat bogs, tar pits, or in ice
• preserved traces of organisms, such as footprints, burrows and rootlet traces - these become covered by layers of
  sediment, which eventually become rock

Question 10

Fossils of the simplest organisms are found in the oldest rocks, and fossils of more complex organisms in the newest rocks. How does this support Darwin’s theory?

Answer 10

simple life forms gradually evolved into more complex ones

Question 11

Evolutionary trees represent the…

Answer 11

relationships between organisms. Branches show places where
speciation
has occurred, and a new species has evolved.

Question 12

amber is…

Answer 12

a substance that is formed from hardened tree sap or resin. This allows the whole organism to be seen clearly.

Question 13

The evolution of the bacteria is an example of…

Answer 13

natural selection

Question 14

Steps of antibiotic resistance

Answer 14

1. random mutations occur in the genes of individual bacterial cells
2. some mutations protect the bacterial cell from the effects of the antibiotic
3. bacteria without the mutation die or cannot reproduce when the antibiotic is present
4. resistant bacteria can reproduce with less competition from normal bacterial strains

Question 15

The number of resistant strains increased because…

Answer 15

partly due to the misuse of antibiotics

Question 16

what can be done to reduce the rate of development of antibiotic resistant strains of bacteria

Answer 16

• doctors should not prescribe antibiotics inappropriately, such as for the treatment of non-serious infections
  2. patients should always complete the full course of antibiotics to ensure all bacteria are killed and none survive to mutate and form resistant strains
  3. the agricultural use of antibiotics should be restricted

Question 17

what factors can cause extinction

Answer 17

• new diseases
• new predators/human hunting/fishing
• new, more successful competitors
• changes to the environment over time, such as climate change or even complete habitat destruction
• a single catastrophic event, such as a massive volcanic eruption or a collision between an asteroid and the Earth
• speciation
• extinction within the food chain

Question 18

describe how dodos went extinct

Answer 18

• Mauritius was colonised by the Dutch in 1638, dodos were hunted for food.
• They were easy to catch and new competitors were brought onto the island, including pigs, cats and rats.
• They ate the dodos’ eggs and their young. Within 80 years, the dodo was extinct.

Question 19

Extinction can cause a decline in..

Answer 19

global biodiversity

Question 20

Indirect vs direct causes of extinction

Answer 20

indirect: don’t immediately create extinctions eg climate change

direct: immediately causes the loss of individuals from a population eg hunting or fishing