B15: Evolution

Question 1

Natural Selection

Answer 1

> The process by which evolution takes place.
Organisms produce more offspring than the environment can support so only those who are most suited to their environment will survive to breed and pass on their useful characteristics.

Question 2

When were the first life forms developed on earth?

Answer 2

3 billion years ago.

Question 3

Lamarck’s Theory

Answer 3

The way organisms behave affects the features of their bodies.
If a particular characteristic is useful to a species, it would grow and develop.
These changes would then be passed onto the offspring.

Question 4

Darwin’s Thoery

Answer 4

Evolution takes place through Natural Selection.

Question 5

4 Key steps to Natural Selection

Answer 5

> Mutation of Gene
Advantage to Survival
Breed
Pass on genes

Question 6

What three types of animal did Darwin study?

Answer 6

Finches, Iguanas and Tortoises

Question 7

Difference between evolution and natural selection

Answer 7

Natural selection is a PROCESS taking many generations.

Evolution is a THEORY of how species changed over millions of years.

Question 8

Why was Darwin’s theory only gradually accepted?

Answer 8

> It conflicted with religious beliefs
Insufficient evidence
Didn’t have a mechanism for explaining inheritance and and variety, as genes weren’t discovered for another 50 years.

Question 9

Why do mutations occur?

Answer 9

Through naturally occurring mistakes made in copying the DNA when the cells divide.

Question 10

Evolution

Answer 10

The process of slow change in living organisms over long periods of time as those best adapted to survive breed successfully.

Question 11

How do we classify organisms

Answer 11

By studying their similarities and differences.

Question 12

A species

Answer 12

A group of organisms that can breed successfully to produce fertile offspring.

Question 13

Evolutionary Tree

Answer 13

a model of the evolutionary relationships between different organisms based on their appearances, and increasingly, on DNA evidence.

Question 14

Ways that fossils are formed

Answer 14

> From the hard parts of an animal.
When one or more of the conditions for decay are not present, e.g oxygen, bacteria.
When harder parts of the organism are replaced by minerals and become part of the rock.

Question 15

How fossils are formed

Answer 15

1. Animal dies and falls to ground.
2. Flesh rots, but skeleton is covered by earth before it too can decay.
3. Over millions of years, the skeleton becomes mineralised and turns to rock.
4. The rocks shift in the earth with the fossil trapped inside.
5. Eventually fossil emerges as earth shifts and erosion takes place.

Question 16

Conditions that affect decay

Answer 16

> Temperature
Moisture Levels
Oxygen Levels
Presence of a decomposer.

Question 17

Throughout history, how many species have existed?

Answer 17

4 Billion

Question 18

Extinction

Answer 18

The permanent loss of all the members of a species.

Question 19

What links all of the causes of extinction?

Answer 19

They all involve a changing in the environment of the organism.

Question 20

What causes extinction

Answer 20

> New Predators
> New Diseases
> The introduction of new competitors.
> Changes to the climate/ environment.
> A single catastrophic event.

Question 21

Geographical Isolation

Answer 21

When two populations become physically isolated by a geographical feature.

Question 22

Endemic

Answer 22

When a species evolves in isolation and is found in only one place in the world.

Question 23

Speciation

Answer 23

When two parts of a population of the same species evolve in different ways until they are unable to interbreed, thus creating a new species.