Old And New Species

Question 1

When did life begin on earth?

Answer 1

3500 million years ago

Question 2

How can we date when different organisms existed?

Answer 2

We can date the rocks that the fossils are found in

Question 3

How can fossils be formed?

Answer 3

• The hard parts of animals do not decay easily eg teeth, bones, shells, claws
• from parts of organisms that have not decayed because some of the conditions for decay were absent e.g fossils of animals preserved in ice
• when parts of an organism are replaced by other materials, such as minerals as they decay
• as preserved traces of organism eg footprints, burrows, root let traces

Question 4

Why are there no traces of early life forms?

Answer 4

They had soft bodies so decayed leaving few traces behind

Question 5

How were the few traces left from early life forms destroyed?

Answer 5

Geological activity such as earthquakes

Question 6

How would 4500 million be written in standard form?

Answer 6

4.5 x 10 to the power of 9

Question 7

What does extinction mean?

Answer 7

A species which once existed has completely died out

Question 8

What can extinction be caused by?

Answer 8

A new disease may kill all members of a species
The environment changes over geological time
New diseases may be introduced
A new predator may evolve or be introduced to a new area
A single catastrophic event may occur which destroys the habitat e.g a massive volcanic eruption
Natural changes in species occur over time

Question 9

What can the fossils records show?

Answer 9

How little or how much an organism has changed over time

Question 10

How can a new predator cause extinction of a species?

Answer 10

It eats all the animals

Question 11

What is a very important factor in determining whether a species will survive?

Answer 11

Climate change, a species adapted to a hot climate may become extinct in the ice age as there may be insufficient food or are unable to breed.

Question 12

What has fossil evidence suggested about why mass extinction occurs?

Answer 12

The habitat the species lives in may be destroyed by catastrophic events such as a major volcanic eruption
The environment can change dramatically following a collision between a giant asteroid and earth

Question 13

What ideas have scientists suggested about why dinosaurs became extinct?

Answer 13

• The collision of a giant asteroid caused huge fires, earthquakes, landslides and tsunamis. The dust which rose masked the sun causing darkness and lower temperature. Plants could not grow
• the extinction was a slower process due to sea ice melting and cooling the sea temperature to about 9 degrees therefore there was less plankton, less food available

Question 14

Suggest another factor that could have led to the dinosaurs dying out

Answer 14

A new disease introduced, unlikely a new predator as dinosaurs were at the top of the food chain

Question 15

What is geographical isolation?

Answer 15

When 2 populations become physically isolated by a geographical feature

Question 16

how could a species be separated?

Answer 16

• an island separates from the mainland
• a new river separates two areas
• mountain rage separates areas
• old craters isolate organisms

Question 17

What will happen in the 2 populations?

Answer 17

They may be exposed to different conditions (food availability, climate, predators) natural selsction will occur in both populations so different characteristics will be beneficial to the two populations

Question 18

Explain the process of speciation

6 mark

Answer 18

• new species will occur following the separation of 2 populations due to geographical isolation
• each population has a wide range of alleles that comtrol their characteristics (genetic variation)
• natural selection will occur in each population, the alleles that control the chacteristics which help the organism to survive are selected. The organisms with these alleles survive to breed
• if the environment, competitors, food supply and predators are different for each population they will evolve differently
• speciation has occurred as the two population can no longer successfully interbreed

Question 19

Explain the process of speciation with 5 terms

Answer 19

Isolation -> 
Variation -> 
Alleles selected -> 
Interbreeding no longer possible -> 
New species

Question 20

What is meant by genetic variation?

Answer 20

The wide range of alleles that control the characteristics in a population

Question 21

How old is the earth?

Answer 21

4500 million years old

Question 22

What is the theory of evolution?

Answer 22

Variation because of mutations
So are better adapted to their environment
Survive to breed
And pass on genetic information to offspring

Question 23

What is a fossil?

Answer 23

The remains of an animal from many years ago left in rock

Question 24

Describe one way in which fossils are formed

Answer 24

• hard parts don’t decay
• no decay as conditions absent
• parts replaced by rock minerals or chemical as they deca

Question 25

What does extinct mean?

Answer 25

All organisms have died out

Question 26

Reasons why an organism may become extinct?

Answer 26

Environment changed
New disease
New predator
New disease
New competitor
Shortage of food 
Mammoths reproduced too slowly 
Mammoths did not adapt to changes

Question 27

Explain how ….. Supports the theory of evolution

Answer 27

Present species evolved from earlier species 
Over long period of time 
Via many gradual changes
Which gave survival advantage 
Passed on genes

Question 28

Which is the most common type of fossil?

Answer 28

The fossils formed when When the harder parts of the animal or plants are replaced by minerals over time as they decay

Question 29

What is it impossible to know how life on Earth began for sure?

Answer 29

Now scientists appt that time
Gaps in the fossil records
Earliest life forms were soft bodies and did not have fossils
Little valid evidence

Question 30

How do ice fossils help scientists check the evidence provided by the main fossil record?

Answer 30

They can improve accuracy and tell us other things such as the colourings of a plant or animal or what it ate
We can also extract DNA from these ice fossils

Question 31

How many species of living organisms are thought to have existed on earth over the years?

Answer 31

4billion

Question 32

Why are ice ages often linked to extinction?

Answer 32

Climate changes cause many species to be wiped out in things like the ice age due to lack of food, too cold to breed and so will die

Question 33

What is mass extinction?

Answer 33

Extinction on a global scale when many species in the world all die out

Question 34

Give two possible causes of mass extinction

Answer 34

Catastrophic events like a volcanoe or collision of giant asteroids
Sudden change in environment, ice age

Question 35

Why is extinction an important part of evolution?

Answer 35

Because it’s the animals that are no longer suited to an enviroment that become extinct, so more advanced creatures can take their place and thrive.

Question 36

What is the evidence that suggest the dinosaurs caused mass extinction of the dinosaurs?

Answer 36

They found rock from long ago formed from lots of minerals which only come about a rock is hit with such force
This caused dust to rise blocking the sun causing plants to die out
Drop in sea temps

Question 37

What is an endemic organism?

Answer 37

When a species evolves in isolation and is found in only one place in the world; it is said to be endemic to that particular area

Question 38

What limitations do fossils have?

Answer 38

You are limited by current technology in how to get information out of them. You cannot tell about the life of an organism by finding one fossil because it’s a snapshot. You need to collect many of them. Also, you cannot tell when the fossil is from down to the exact year.

Question 39

How does evolution take place?

Answer 39

Variation occurs caused by random mutation

The best adapted survive by natural selection and breed passing their genes to their offspring