B15: Genetics and Evolution

Question 1

What are fossils?

Answer 1

remains of organisms from millions of years ago that can be found in rocks, ice and other places

Question 2

Ways a fossil is formed?

Answer 2

• absence of decay due to conditions needed for decay not being there (eg. too low temp, oxygen)
• the hard parts of the animal being replaced with minerals as they decay and they become part of the rock
• preserved traces of an organism, ie. footprints, droppings etc.

Question 3

Reasons the fossil record is incomplete?

Answer 3

• many of the earliest life form on earth were soft-bodied and so left little fossil trace
• the majority of any of the earliest fossils would have been destroyed by geological activity (eg formation if mountain ranges, volcanoes, earthquakes…)
• most organisms didn’t fossilise as conditions weren’t right
• undiscovered fossils

Question 4

Factors that may cause extinction? (6)

Answer 4

• new predators
• new diseases
• new, more successful competitors
• changes to environment
• single catastrophic event
• collisions with asteroids

Question 5

D. Extinction?

Answer 5

the permanent loss of all members of a species

Question 6

Most recent mass extinction?

Answer 6

the dinosaurs

Question 7

How did asteroid kill dinosaurs? (5)

Answer 7

caused:

• tsunamis
• earthquakes
• wildfires
• landslides
• dust would have made planet dark and caused global decrease in temp –> global winter

Question 8

Evidence for asteroid theory?

Answer 8

• crater in mexico containing a layer of rock formed by crater debris
• deep below crater, scientists found lots of iridium which is only formed when rock is hit with a massive force

Question 9

Why can bacteria evolve rapidly?

Answer 9

because they reproduce fast

Question 10

D. Classification?

Answer 10

the organisation of living things into groups according to their similarities

Question 11

Who created the classification system we use today?

Answer 11

Carl Linnaeus

Question 12

D. Species?

Answer 12

smallest group in Carl’s system. members of the same species are very similar - a group of organisms that can breed together to produce fertile offspring

Question 13

D. Archaea?

Answer 13

one of 3 domains, containing primitive forms of bacteria that can live in many of the extreme environment of the world

Question 14

5 kingdoms that used to be used?

Answer 14

prokaryotes, protista, fungi, plants, animals

Question 15

D. Eubacteria?

Answer 15

normal bacteria (like stuff grown in labs at school)

Question 16

How were the 6 kingdoms made?

Answer 16

prokaryotes were divided into archaea and eubacteria

Question 17

Main kingdoms in the origional Linnaean classification system?

Answer 17

animals and plants

Question 18

Main kingdoms in the mordern classification system?

Answer 18

protista, fungi, plants, animals,archaea and eubacteria

Question 19

3 Rules for writing scientific names?

Answer 19

• first part of name = genus, written with capital letter
• second name = species, written in lower case
• names are underlined if handwritten and in italics if typed

Question 20

What did Linnaeus classify things into?

Answer 20

kingdom, phylum, class, order, family, genus, species

Question 21

binomial system?

Answer 21

genus and species

Question 22

D. Domain?

Answer 22

new higher level of classification above the kingdom

Question 23

3 domains (currently used) proposed by Woese?
eg's

Answer 23

• Archea - primitive bacteria
• Bacteria - true bacteria
• Eukaryota - plants animals fungi protists

Question 24

Archea?

Answer 24

Primitive form of bacteria, including extremophiles. Contains 1 kingdom, archaebacteria

Question 25

Bacteria?

Answer 25

True bacteria and the cyanobacteria, bacteria-like organisms that can photosynthesis

Question 26

Eukaryota?

Answer 26

organisms with cells that contain a nucleus enclosing genetic material. 4 kingdoms: protista, fungi, plants and animals

Question 27

D. Evolutionary trees?

Answer 27

models used to explain evolutionary links between groups of organisms

Question 28

Linnaeus’ system? (order in)

Answer 28

kingdom - phylum - class - order - family - genus - species

Question 29

2 parts of binomial name?

Answer 29

genus, species

Question 30

Why were new models of classification proposed?

Answer 30

• microscopes improved so scientists knew more about cells

- biochemical processes became better understood

Question 31

Who proposed the three-domain system?

Answer 31

Carl Woese