Evolution

Question 1

When did life originate & how?

Answer 1

~2000 mya; non-cellular aggregates → cells with membrane; mechanism unknown; early cells released O₂ (photosynthesis-like)

Question 2

Early evolution of organisms

Answer 2

Unicellular → multicellular; invertebrates active ~500 mya

Question 3

Origin of fishes & plants timeline

Answer 3

Jawless fishes ~350 mya; plants ~320 mya; plants invaded land first (less dependence)

Question 4

Transition from water to land

Answer 4

Fish developed strong fins → moved to land (~350 mya); lobe-finned fish → amphibians; coelacanth rediscovered 1938

Question 5

Early plant evolution

Answer 5

Chlorophyte → tracheophyte ancestors; early plants: Rhynia, Psilophyton

Question 6

Major plant groups evolution

Answer 6

Bryophytes → Pteridophytes → Gymnosperms → Angiosperms (monocots & dicots)

Question 7

Important plant transitional forms

Answer 7

Seed ferns (between pteridophytes & gymnosperms); progymnosperms (gymnosperm ancestors)

Question 8

Origin of reptiles

Answer 8

Reptiles evolved from amphibians

Question 9

Reptile diversification

Answer 9

Turtles, lizards, snakes, tuataras, crocodiles

Question 10

Evolutionary lineages

Answer 10

Synapsids → mammals; sauropsids → reptiles & birds

Question 11

Important extinct reptile groups

Answer 11

Pelycosaurs, thecodonts, therapsids (mammal-like reptiles)

Question 12

Dinosaurs & birds

Answer 12

Dinosaurs dominant (e.g. T. rex ~20 ft); extinct ~65 mya (likely climate); small reptiles → birds

Question 13

Plant & fossil significance

Answer 13

Giant ferns dominated → formed coal deposits

Question 14

Rise of mammals

Answer 14

After reptiles, mammals dominated; early mammals small, shrew-like, viviparous, intelligent

Question 15

Continental drift effects

Answer 15

South America fauna replaced by North America; Australian mammals survived due to no competition

Question 16

Aquatic mammals

Answer 16

Whales, dolphins, seals, sea cows

Question 17

Early human ancestors

Answer 17

Dryopithecus (ape-like), Ramapithecus (man-like) ~15 mya; fossils in Ethiopia & Tanzania; upright walking ~3–4 mya

Question 18

Australopithecus

Answer 18

Lived in grasslands; ate fruits; used stone tools

Question 19

Homo evolution

Answer 19

H. habilis (650–800 cc, no meat) → H. erectus (~900 cc, meat) → Neanderthal (1400 cc, 100k–40k yrs, hides, burial)

Question 20

Homo sapiens & culture

Answer 20

Origin Africa; modern humans 75k–10k yrs; cave art ~18k yrs (Bhimbetka); agriculture ~10k yrs; baby chimp skull ≈ adult human

Question 21

Natural selection

Answer 21

When organisms that are best suited to their environment can reproduce well in changed environmental conditions and survive.

Question 22

Adaptive radiation

Answer 22

The process of evolution of individuals each different from the other an ancestral stock of the same geographical area starting from and literally radiating to other geographical areas

Question 23

Types of Darwin finches

Answer 23

Large ground finches
Cactus ground finches feeding on cacti
Wood pecking finches
Insectivorous finches
Warbler finches

Question 24

What is saltation?

Answer 24

Single step large mutation that causes species formation

Question 25

What are mutations?

Answer 25

Sudden inheritable variations which causes species variations and thus cause evolution hence called it saltation.