B15 Genetics and evolution

Question 1

What theory did Dawin propose

Answer 1

Natural selection

• organisms in a species show a wide range of characterists
• those most suited are more likely to survive and reproduce
• these characteristics are passed onto the next generation

Question 2

Why were darwins theories not accepted

Answer 2

• Theory challenged the idea that God made all animals and plants
• Insufficient evidence to convince scientists
• method inheritance and variation was not understood until 50 years post

Question 3

Jean-Baptiste Lamark

Answer 3

• Changes occur during an organisms lifetime
• And those changes can be passed

eg.

• giraffes strech their necks to eat leaves
• getting braces so your kids have straight teeth

however

• we know that this cannot occur

Question 4

Mendel

Answer 4

• Mendel studied organisms with distinctive traits
• he observed that inheritance of characteristics was based on ‘units’
  • that could be dominant
  • or recessive
• which are passed down onto descendents

Question 5

why was mendels work not appreciated?

Answer 5

• He did not publish his work in scientific journals
• people weren’t aware of genes, DNA or chromosomes

Question 6

First Cell divison

Answer 6

• Chromosomes in cell division was observed in 19th
• In 20th scientist realsied that Mendals ‘units’ were on genes

Question 7

why do we understand genes

Answer 7

• determination of structure of DNA
  • mid 20th
• and futher work by scientists

Question 8

What evidence do we have now that supports natural selection

Answer 8

• we understand how genes work and see it in inheritance
• Fossil records
• antibiotic resistance

Question 9

describe what speciation is

Answer 9

• when two populations of species
• become so different in phenotype
• that they cannot breed to produce fertile offsrping

Two new species formed

Question 10

how does speciation occur

Answer 10

• Population become geographically isolated from the rest of the population
• There are different environmental conditions in the new population
• Different alleles are advantageous, leading to them being selected
• natural selection occurs where those who are better adapted survive
• The new population changes to a point when it can no longer breed to produce fertile offspring
• = Speciation

Question 11

Who also throught of natural selection

Answer 11

• Alfred Wallace
• they both thought of it independently
• There work together pushed Darwin to publish ‘On the Origin of Species’

Question 12

What is Wallace best known for

Answer 12

• theory on speciation
• warning colouration in animals

Question 13

what are fossils

Answer 13

• remains of organisms from millions of years
• found in rocks

Question 14

How are fossils formed (quick fire 3)

Answer 14

• no decay
• decay and replace
• casting

Question 15

Fossils: No decay

Answer 15

• Parts of organisms have not been decayed
• Because conditions are absent
  • oxygen
  • moisture
  • warmth

Question 16

Fossil: Decay and replace

Answer 16

• Parts of the organism is decayed
• and replaced by minerals

Question 17

Fossil: Casting

Answer 17

• Traces such as footprints and burrows
• remain due to hardening ground around them

Question 18

What can fossils be used for?

Answer 18

• Show how bodies of organisms have changed over time
• Compare how closely related two organisms are
  • looking for similarites
  • information used to form evolutionary trees

Question 19

What cannot fossils be used for?

Answer 19

Tell us how life started

• Most early life forms were soft bodied
  • decayed completely
• Any traces have been destroyed by geological activity

Question 20

what is exctiniction

Answer 20

when an entire species has died out

Question 21

What might cause extinction

Answer 21

• Changes in environment which the specie cannot adapt fast enough to
• New predators evolved or migrated
• New disease arises and there are no resistant alleles
• Competition with a specie that has advantageous alleles for the same food source
• Catastrophic event
• Destruction of habitat

Question 22

Why do bacteria evolve faster than humans

Answer 22

They reproduce more rapidly

Question 23

how are resistant bacteria formed

Answer 23

• random mutation causes bacterial pathogen to be resistant
• When exposed to antibiotic they survive
• They have reduced competition for food so can reproduce
  • by binary fission
  • can also pass resistance on
• Strain will spread as people are not immune to it

Question 24

How can we reduce the number of resistant bacteria

Answer 24

• Doctors should not prescribe antibiotics if

  - not a serious infection 

  • a viral infection
• Patients should finish their course of antibiotic
  • all bacteria killed
  • none mutate to become resistant
• restrict agriculutral use

Question 25

How have things been classified traditionally (CL)

Answer 25

- groups depending on structure and characteristics - by carl linnaeus

Question 26

What is the order for classification

Answer 26

- Kingdom - Phylum - Class - Order - Family - Genus - Species

Question 27

How are organisms named

Answer 27

- Genus + Species - Genus = capital letter - Species = lower case - all underlined

Question 28

Why were new models of classification proposed

Answer 28

- evidence of internal structures - due to microscopes - increased understanding of biochemical processes

Question 29

What is the 'three domain system'

Answer 29

- Carl Woese - able to do so due to evdience from chemical analysis Organisms are divided into - Archaea --> primative bacteria - Bacteria --> true bacteria - Eukaryota --> protist, plant, animal, fungi