A2 Mass Extinctions

Question 1

Extinction

Answer 1

where a species is no longer alive. It is usually judged as when the last member of a species dies and therefore cannot reproduce. Well over 99% of the species that have ever lived are now extinct.

Question 2

Species

Answer 2

groups of individuals with the ability to reproduce and to give rise to fertile offspring. Palaeontologists use morphology to define species as we have no way of knowing this information.

Question 3

Genera

Answer 3

(genus) a subdivision in taxonomy, a broader category than species.

Question 4

Albedo effect

Answer 4

the extent to which an object or medium reflects light. For example, snow, will reflect a high percentage of light energy, reducing the amount absorbed as heat energy.

Question 5

Traps

Answer 5

large-scale volcanism resulting in the formation of mafic igneous rocks.

Question 6

Pangaea

Answer 6

the name given to the supercontinent which formed at the end of the Permian.

Question 7

Shocked quartz

Answer 7

grains that have characteristics showing deformation under high pressure. It was first discovered at nuclear testing sites, and linked with meteorite impacts.

Question 8

Iridium

Answer 8

a transition element, rare on Earth, but found in meteorites. Luis Alvarez (1980) first proposed this as evidence that a giant object hit the Earth.

Question 9

Tektites

Answer 9

spheres or irregular shaped lumps of solidified molten rock, a few centimetres in diameter, black or green in colour, which are thought to have formed as a result of extremely high pressures and temperatures caused by a meteorite impact.

Question 10

Tsunami

Answer 10

a massive displacement of water, formed either due to an underwater earthquake or a meteorite impact.