Evolution of major groups of organisms

Question 1

What did the modern plant body plant evolve in response to?

Answer 1

Maximising light via foliage
Maximising water and nutrient capture via roots
And roots providing anchorage
Also extremes of climate, water conservation and physical defence against herbivores

Question 2

What is the current dominant plant group?

Answer 2

Angiosperms

Question 3

How did angiosperms become dominant (what advantageous traits do they have)?

Answer 3

‘Biochemical shield’ to defend against herbivores
Faster growing
Efficient pollination systems

Question 4

What is a body plan?

Answer 4

The way in which the body cavity, organs, appendages, supporting structures and nervous systems are organised

Question 5

What did arthropods evolve from?

Answer 5

An annelid-like ancestor

Question 6

Describe arthropods.

Answer 6

Rigid, tubular exoskeleton
Highly diverse
In most habitats

Question 7

What is the Cambrian explosion?

Answer 7

Sudden appearance in fossil records of complex animals

Question 8

What has been argued to have played a key role in the Cambrian explosion?

Answer 8

Evolution of eyes

Question 9

Describe compound eyes.

Answer 9

Repeating units of ommatidia , each of which functions as a separate visual receptor
Form a mosaic image
Provide wide visual range, sometimes full 360 degrees

Question 10

What is silk and what is it used for?

Answer 10

Ductile protein fibre
Secreted by organs e.g. spinnerets in spiders
Used mainly in prey capture by spiders and as protection by insects

Question 11

What is winglessness in insects usually an adaptation to?

Answer 11

A parasitic lifestyle

Question 12

What is the benefit of the pupal stage in insects?

Answer 12

Enabled larval and adult stages to occupy different niches and avoid competition between larvae and adults

Question 13

Describe the development of molluscs.

Answer 13

Appearance of molluscs
Coincided with trebling of calcium levels in seawater due to tectonic/ volcanic activity
Shell= exoskeleton
Muscular foot for locomotion or prey capture
Shell eventually reduced or lost in some

Question 14

What is the mollusc radula?

Answer 14

An array of horney protuberances (teeth) used to rasp day at algae, etc
Absent in bivalves (oysters, clams, etc)
Worn/ broken teeth are replaced by new ones

Question 15

Describe echinoderms.

Answer 15

Spiny-skinned animals like sea urchin and starfish

Radial symmetry

Question 16

What are vertebrates?

Answer 16

Animals with internal backbone that encloses dorsal, hollow nerve cord

Question 17

What did teeth in fish develop from?

Answer 17

Armour of early fishes was made of dentine tubercles
Tubercules became more pronounced around and in the mouth to become teeth
Dentine= calcified tissue

Question 18

Why was the development of bones and their associated musculature in fish useful?

Answer 18

Major advance for positional control
Whole body movements not always required
Enables massive diversification in body shape

Question 19

What does the swim bladder do?

Answer 19

Internal gas filled organ that contributes to the ability of many bony fish to control buoyancy, can maintain water depth without having to swim (saves energy)

Question 20

What is the lateral line system in bony fish?

Answer 20

Sensory system that detects movement and vibrations (and electrical impulses in some fish)
Used to avoid collision, predation, detect prey and enable orientation

Question 21

What did colonisation of the land by vertebrates require?

Answer 21

Advances in mechanical support (bony skeleton) and respiratory gas exchange (lungs)

Question 22

What was the benefit of colonising the land for vertebrates?

Answer 22

Plenty to eat at that time

Plenty of new niches to occupy

Question 23

Which bony fishes led to land tetrapods?

Answer 23

Panderichthyids most likely 
Really ugly marine fish
Flattened head
Long tail 
4 lobed fins

Question 24

What is limb loss in some amphibians associated with?

Answer 24

Burrowing and swimming

Question 25

What intrinsic factors led to the success of reptiles?

Answer 25

Insemination/ fertilisation became internal
Development of amnion: membrane enclosing embryo in liquid. Less dependent on aquatic habitats for reproduction
Scaly skin

Question 26

What extrinsic factors led to reptile success and diversification?

Answer 26

Global warming: fragmentation of tropical rainforests isolates populations. Speciation time boissss
Climate-caused demise of amphibians. No more competition ayyyyy

Question 27

What would port-wings have possible been used for in birds?

Answer 27

Enable lift, glide for short durations, low altitude leaps when running
Possibly assist prey capture/ evade predators

Question 28

What happened as a result of the K-T event?

Answer 28

Around 66% of all mammal species go extinct
Surviving mammals radiate greatly
Within 25M years, massive bodied species had evolved
Mammals released from competition with dinosaurs
More above ground and day time activity

Question 29

What are the differences between apes and man?

Answer 29

Skeleton specialised for sustained upright walking
Large brain coupled with high intelligence and modified cranium
Rounded dental arch with canines reduced to same length as other teeth

Question 30

When did our ancestral lineage and chimpanzee lineage split?

Answer 30

Before 5 mya

Question 31

What it the benefit of the Epicanthic fold?

Answer 31

Thought to protect eyes from excessive UV, strong winds an cold
e.g. conditions prevalent in Central Asian Steppes and Arctic

Question 32

What is Steatopgyia?

Answer 32

Extreme development of the buttocks
Ability to store large amounts of fat is important in very seasonal environments
Once widespread in Africa, confined to a few populations now