History of life on earth

Question 1

Ice ages

Answer 1

Long periods of time when the earth experienced really cold weather

sheets of ice called glaciers were formed

Question 2

Glaciation

Answer 2

The process of formation of large sheets of ice

Glaciation and the sudden cooling it brought about caused large scale extinction of life forms

Question 3

What was responsible for glaciation

Answer 3

the changing positions of the continents and upward movement of continental blocks were responsible for it

Question 4

Continental drift

Answer 4

The main theory scientists use to explain the formation of glaciers during the ice ages

According to the theory all the continents were one big land mass or super continent called Pangaea

Question 5

Biogeography

Answer 5

The study of the past and present distribution of individual species

Question 6

Theory of plate tectonics

Answer 6

The earth is made up of about a dozen large plates which fit together like a jigsaw puzzle

The plates lie on top of a much hotter material which allows the plates to move upwards even up to this day

Question 7

Fossils

Answer 7

The remains of ancient life forms preserved in the rocks.

Question 8

Describe how the concentration of in earth’s atmosphere affected the history of life

Answer 8

The absence of oxygen allowed the gases in the atmosphere to form organic molecules such as fatty acids or protein which are the building blocks of living organisms.

As more oxygen was released into the atmosphere, living organisms that needed oxygen to release their food developed

Scientists believe that the absence of oxygen led to the creation of life and the increase in oxygen levels led to an increase in the diversity of living organisms

Question 9

The gas that was in extremely small quantities or completely absent when life started on earth

Answer 9

Oxygen

Question 10

The gas that increased in the atmosphere when the photosynthetic bacteria developed

Answer 10

Oxygen

Question 11

The geological epoch that we are now living in

Answer 11

Holocene

Question 12

The geological time period during which the major groups of animals appeared

Answer 12

Cambrian

Question 13

Geological time period when animals flourished

Answer 13

Jurassic

Question 14

The oldest phyla of invertebrates that appeared on earth

Answer 14

Polyphyra

Question 15

Recent class on vertebrates that appeared on earth

Answer 15

Mammalia

Question 16

Extinction

Answer 16

The process by which living organisms die off so that not a single member of the species exists

Question 17

Mass extinction

Answer 17

The disappearance of more than 50 percent of the earth’s species in the geological instant of a few years

Question 18

Megafauna extinction

Answer 18

The name given to the extinction characterized by the death of large animals such as the dodo and woolly mammoth

Question 19

The solid formed from the hardening of the liquid sap of trees

Answer 19

Amber

Question 20

Radiometric dating

Answer 20

The process of finding out the ages of rocks and fossils using radioactive elements

Question 21

Relative dating

Answer 21

The process of finding out the ages of rocks and fossils by comparison with another fossil or rock

Question 22

Radioactive substances

Answer 22

Substances which give off nuclear radiation and decay into other substances

Question 23

two forms of fossils formed in rocks

Answer 23

Casts and impressions

Question 24

Three places other than rocks in which fossils have been found

Answer 24

Amber
Ice
Tar Pits

Question 25

Impacts of humans on biodiversity

Answer 25

Habitat destruction Natural disasters Over exploitation Pollution Disease Invasion by Alien species Climate change including ozone depletion and global warming overuse of pesticides and fertilizers

Question 26

Examples of fossil fuels found in rocks

Answer 26

Bones of vertebrate animals shells or exoskeleton of invertebrates tracks(footprints), burrows and hardened faces of animals petrified tree trunks imprints of leaves and small animals