3.2 origens of biodivesity

Question 1

define speciation?

Answer 1

it is the formation of new species when populations of a species are isolated and evolve differently.

Separation may have geographical or reproductive causes.

speciation is a gradual change, humans can speed up speciation by artificial selection. of plants and animals by genetic energy.

Question 2

what are the main mechanisms of natural selection?

Answer 2

variation, fitness, reproductive success, inheritance.

Question 3

can you expand on variation of a mechanism of natural selection?

Answer 3

species show variation in appearance or behaviour. Variation occurs due to genetic diversity, changes in the gene pool of a species arise through mutation + sexual reproduction.

Question 4

can you expand on fitness of a mechanism of natural selection?

Answer 4

resources such as food and space are limited are there are not enough for all offspring. There is therefore competition for resources where certain individuals will be fitter and better adapted to the environment.

Question 5

can you expand on reporductive success of a mechanism of natural selection?

Answer 5

fitter individuals will be able to outcompete others for resorces and will be at an advantage to reproduce more sucessfully than unfit individual.

Question 6

can you expand on inheritanse of a mechanism of natural selection?

Answer 6

the individuals that survive and reproduce contain genes that give them an adaptive advantage. These genes are inherited by the offspring and passed onto the next generation. Over time, change in the gene pool leads to speciation.

Question 7

list three physical barriers that may separate populations?

Answer 7

mountains, oceans climate

Question 8

what are some other barriers that separate popualtions?

Answer 8

behavioural differences (reproductive isolation)
environmental gradients

Question 9

outline the factors which might provide different selection pressures on populations that have been split?

Answer 9

competition, disease, predation, parasitism, environmental pressures.

Question 10

using modern continents/ nations, outline the structure of the ancient continent ‘Gonewanda’?

Answer 10

Gonewanda was made of India, Africa, Australia, Antartica and South America.

Question 11

with reference to tectonic plates, explain how Gonewanda became what it is today?

Answer 11

plate tectonic movement began about 180 million years ago. Africa and South America broke apart from Gonewanda, they later split to form the South Atlantic Ocean.

Madagascar moved away from India, as both moved away from Australia + the Antartic, they split later with Australia moving northward.

Question 12

explain how to land bridge may influence the evolution of a species?

Answer 12

sea level changes caused by climate change have led to higher altitude areas becoming isolated or have provided land bridges for the migration of species to new areas.

this allows different spices to develop with changing environmental conditions.

Question 13

explain ‘back ground extension rate’?

Answer 13

The natural extinction rate of all species.

One speices per million spcieses per year, this is between 10-100 species a year.

Question 14

explain the term ‘mas extenction’?

Answer 14

periods in Earth’s history when very large numbers of spies due put simultaneously or within a very short period.

Question 15

how many mass extnctions have happended that are not huma related?

Answer 15

5

Question 16

outline three things that may have led to mas extensions in the past?

Answer 16

• drop in sea levels, first mass extinction at the end of the Ordovician period. Sea levels dropped as glaciers formed,

-astroid and volcanos at the end of the Permian era, a huge release of carbon dioxide and oxygen reduced sea level.

-undersea volcanic eruption at the end of the Triassic period, flood-like lava escaping from a volcano in the Atlantic Ocean.

• astroid or commit impact, terrestrial mas extinction.

Question 17

what are the geological time period you needed to know of?

Answer 17

Ordovician 438 million years ago

devonian 364 million years ago

Permian Tirassic 251 million years ago

End Trassic 199-214 million yeas ago

cretaceous Tertiary 65 million years ago.

Question 18

what is a family in biology?

Answer 18

a family is a group of species, a family can contain up to one thousand species.

Question 19

what was the extinction rate of families in the different geological periods?

Answer 19

Ordovician 25%

devonian 19%

Permian Tirassic 54%

End Trassic 23%

cretaceous Tertiary 17% (all dinosaurs)