UNIT 4 10A: Changes in biodiversity over time

Question 1

Geological time scale

Answer 1

A scale dividing earth’s history into intervals according to the geological and biological events and conditions present at that time

Question 2

Biodiversity

Answer 2

The variety of plant and animal life in an ecosystem at any given time

Question 3

Plate tectonics

Answer 3

A scientific theory that focuses on the separation of earth’s crust into plates that move across the underlying mantle

Question 4

Cynobacteria

Answer 4

A group of prokaryotic organisms that are capable of photosynthesis; recognised as the earliest form of life on Earth

Question 5

Stromatolite

Answer 5

A structure that consists of layered deposits made by cynobacterial colonies; are among earliest fossils known

Question 6

Invertebrae

Answer 6

An organism that doesn’t have a backbone

Question 7

Arthropod

Answer 7

A type of animal that has no internal backbone, a segmented body and a hard external covering known as an exoskeleton

Question 8

Brachiopod

brachio = backbone

Answer 8

A marine animal with no internal backbone and a hinged upper and lower shell

Question 9

Chordate

Answer 9

Any animal that contains evidence of a spinal cord at some point in its development

Question 10

Vertebrae

Answer 10

Having a backbone

Question 11

Amphibians

Answer 11

Tetrapods that are semi-terrestrial, with young living in water before moving to land as adults

Question 11

Reptiles

Answer 11

A class of air-breathing tetrapods with skin covered in scales
Lay eggs on land

Question 11

Theropod

Answer 11

A type of carnivorous dinosaur with short forelimbs that ran on powerful hind legs

Question 12

Niche

Answer 12

The role that a species plays within its ecosystem

Question 13

Hominoid

Answer 13

A superfamily consisting of all current and extinct humans and apes

Question 14

Hominin

Answer 14

Subfamily consisting of all current and extinct bipedal primates

Question 15

Background extinction rate

Answer 15

The normal extinction rate expected to occur over a period of time due to natural environmental factors

Question 16

mass extinction

Answer 16

Widespread and rapid decrease in the biodiversity of earth

Question 17

Steps in natural selection

Answer 17

1) Variation exists in original population
2) Selection pressure removes individuals with a selective disadvantage, making it more difficult to survive and reproduce
3) Certain phenotype provides selective advantage
4)Over time, individuals with a selective advantage survive and reproduce, passing on their genes to the next generation