b6 - fossils & extinction

Question 1

what is meant by evidence?

Answer 1

the available body of facts indicating whether a belief is true or valid

Question 2

what evidence is there for evolution?

Answer 2

• fossils
• dna analysis of species

Question 3

what are the problems with fossil evidence?

Answer 3

• only few organisms form fossils
• certain conditions are necessary for fossils to form
• fossils can be damaged e.g via geological activity

Question 4

define and explain how the relative ages of fossil species are worked out.

Answer 4

radiometric dating - as layer upon layer of rock is added, each must be younger than the one beneath it

Question 5

define ‘ fossils ‘

Answer 5

remains of organisms from thousands of years ago, found in rocks

Question 6

which parts of an animal or plant are actually fossilised?

Answer 6

skeleton

Question 7

what fossil traces of organisms have been found?

Answer 7

footprints , burrows , spaces left by plant roots

Question 8

where have whole organisms been found?

Answer 8

insects and plant parts: trapped in amber ( a hardened form of tree sap )

tree trunks: buried in mud containing volcanic ash

Question 9

define ‘ extinction ‘

Answer 9

the act of a species dying out resulting in no more of the species existing on the planet

Question 10

list direct and indirect acts to extinction:

Answer 10

direct: - hunting
- poaching

indirect: - global warming
- competition

Question 11

list the 4 main human causes to extinction:

Answer 11

• habitat destruction
• introduced species
• hunting and fishing
• environmental change

Question 12

list examples of natural causes for extinction:

Answer 12

• new predators
• new diseases
• a single catastrophic event
• competition

Question 13

how are fossils formed?

Answer 13

( sediment ) an animal is buried by sediment shortly after it dies

( layers ) more sediment layers accumulate above the animal’s remains and minerals

( movement ) movement of tectonic plates lift up the sediments and pushes the fossil closer to the surface

( erosion ) erosion from the rain, rivers and wind wear away the remaining rock layers

Question 14

what is genetic modification?

Answer 14

a technology that inserts dna into the genome of an organism

Question 15

define heterozygous

Answer 15

when 2 alleles are different to the gene

Question 16

how does genetic modification work?

Answer 16

• a gene for a target feature is selected
• the gene is cut out from the organism’s dna
• the gene is inserted into the target organism’s dna
• the organism is grown to see if modification has worked and reached the target

Question 17

how do resistant strains of bacteria occur?

Answer 17

there is a variation in bacteria ( some are anti-biotic resistant )
the unwell organism takes the antibiotic
the antibiotic kills non-resistant bacteria strains’
resistant bacteria strains remain
bacteria reproduces by asexual reproduction
host feels ill again

Question 18

what type of enzyme breaks down starch?

Answer 18

carbohydrase

Question 19

define allele

Answer 19

different forms of a gene

Question 20

what are the safety concerns of genetic modification?

Answer 20

• cause allergic reactions
• cancer causing

Question 21

who proposed the classification theory?

Answer 21

carl linnaeus

Question 22

label the classification system

Answer 22

kingdom
phylum
class
order
family
genus
species

Question 23

name the 4 nucleotide types

Answer 23

adenine
guanine
thymine
cytosine

Question 24

define homozygous

Answer 24

when 2 alleles are same to the parents