5.2 - natural selection

Question 1

the theory of evolution by natural selection was proposed by

Answer 1

Charles Darwin

Question 2

survival of the fittest

Answer 2

in order for a species to survive a change in the environment they must be able to adapt and evolve - within a species only the best adapted survive

Question 3

the theory of natural selection states that

Answer 3

• within a species there is always natural variation
• organisms produce more young than will ever survive
• there will be competition for resources
• only the best adapted survive - survival of the fittest
• those that survive pass on their advantageous characteristics to their offspring

Question 4

selection pressures

Answer 4

an environmental factor that determines which individuals survive/reproduce
- ABIOTIC - non-living
- BIOTIC - living

Question 5

adaption

Answer 5

any variation that enables an individual to survive / reproduce is referred to as an adaption

Question 6

Why Darwin’s ideas were so contentious?

Answer 6

• not enough evidence
• thought God created all species individually
• some objected to the idea humanity evolved from apes

Question 7

what did Darwin not know for his theory to be fully accepted by academics

Answer 7

• about gene and how info was passed on to the next generation
• no proof of natural selection

Question 8

who found out about genes

Answer 8

Gregor Mendel

Question 9

how does natural selection work (5/6)

Answer 9

• a random mutation occurs in an allele in an individual - gives genetic variation
• the new allele codes for a trait which gives the individual some competitive advantage
• the individual is more likely to survive and reproduce
• the allele is passed onto its offspring
• the offspring has the trait so has a competitive advantage
• over many generations the frequency of the new allele increases

Question 10

evolution vs natural selection

Answer 10

e - the gradual change in the diversity of species - some species go extinct + new species arise
ns- PROCESS by which evolution take place

Question 11

John Baptiste Lamarck

Answer 11

• believed characteristics obtained in a parent during their lifetime could directly be passed onto their child
• also believed that by strengthening body parts in a lifetime e.g., if parent good tennis player offspring inherits it

Question 12

HMS Beagle + Galapagos Islands - Darwin’s observations

Answer 12

• offspring outnumber parents
• population sizes remain stable over a long time
• no 2 individuals are identical - variation occurs in a population
• offspring tend to resemble parents

Question 13

Darwins 3 deductions

Answer 13

• struggle to survive
• only best adapted survive
• characteristics can be pased onto offspring over time - favourable characteristics accumulate and may give rise to a new species

Question 14

evolutionary tree

Answer 14

species evolve from a common ancestor

Question 15

darwins evidence - finches

Answer 15

13 different types of beaks
- each beak adapted to food it eats - different selection pressures (on each island) drive natural selection
- food was diff on each island so each bird had to adapt to the food on its island

Question 16

conditions needed for evolution

Answer 16

• all organisms produce more offspring than survive to adulthood
• population remains more or less constant in numbers - birth/death rate in balance
• members of same species show variation
• some favourable characteristics are inherited and so are passed onto next generation