Natural Selection and Evidence for Evolution

Question 1

Natural selection method

Answer 1

Genetic variation occurs due to different alleles and new ones arising from mutations
Selection pressures e.g. diseases, predation and competition over resources affect an organism’s chances of surviving and reproducing
Individuals with better-adapted characteristics have better chances to survive and reproduce
This makes their better-adapted alleles more likely to be passed on
Less adapted individuals have lower chance of doing so
Beneficial characteristics become more common in a population over time

Question 2

Bacterial drug resistance as evidence for evolution

Answer 2

Bacteria is introduced to an antibiotic
Some bacteria have better resistance to it due to random mutations
Bacteria with weaker/no resistance die
Bacteria with better resistance survive and reproduce
Resistance becomes more common in population

Question 3

Fossil definition

Answer 3

Any trace of an organism that lived a long time ago
Commonly found in rock
Deeper the rock, older the fossil

Question 4

Observation of evolution through fossils method

Answer 4

Arrange fossils of a species in chronological order

Observe gradual change in organism

Question 5

Theory of Evolution

Answer 5

Variation in members of same species and those with characteristics most suited to environment were most likely to survive and pass on those characteristics

Question 6

Effect of theory of evolution on classification

Answer 6

All organisms are related by a common ancestor so we now classify organisms based on how closely related they are

Question 7

Effect of theory of evolution on antibiotic resistance

Answer 7

We constantly develop new antibiotics to fight newly evolved resistant bacteria
We know to finish the course of drugs to prevent resistant bacteria spreading

Question 8

Effect of theory of evolution on conservation

Answer 8

We know the importance of genetic diversity and how it helps populations adapt to changing environment
Has led to conservation projects to protect species

Question 9

Ardi facts

Answer 9

Fossil of Ardipithecus ramidus
4.4 million years old
Structure of feet suggests species climbed trees (ape-like big toe)
Had long arms and short legs (more like ape than human)
Brain size was most similar to a chimpanzee’s
Structure of legs suggested she walked upright (like humans)

Question 10

Lucy facts

Answer 10

Fossil of Australopithecus afarensis
3.2 million years old
Arched feet so more adapted to walking than climbing (like humans)
Size of arms and legs were between apes and humans
Brain was slightly larger than Ardi’s but still similar to a chimp’s
Structure of legs and feet suggested she walked upright and more efficiently than Ardi’s

Question 11

Turkana Boy facts

Answer 11

Fossil of Homo erectus
1.6 million years old
Short arms and long legs (more human than ape)
Much larger brain that Lucy’s (similar to human’s)
Structure of legs and feet suggests species was even better adapted to walking upright than Lucy

Question 12

Other evidence for human evolution

Answer 12

Structural features of tools near fossils (simpler tools = older)
Stratigraphy (studying of rock layers) (deeper layers = older)
Stone tools with carbon-containing material (carbon dating)
Pentadactyl limbs

Question 13

Pentadactyl limbs

Answer 13

Limbs with five digits
Used in many species but with different purposes
Similar bone structures suggests how they all evolved from similar ancestors

Question 14

Order of classification

Answer 14

Domain (archaea, bacteria, eukarya)
Kingdom (animals, plants, fungi, prokaryotes, protists)
Phylum 
Class
Order
Family
Genus (used in naming)
Species (used in naming)

Question 15

Archaea domain definition

Answer 15

No nucleus with some unused DNA present

Question 16

Eukarys domain definition

Answer 16

Nucleus with some unused DNA present

Question 17

Bacteria domain definition

Answer 17

No nucleus with all genes used for something

Question 18

Order of classification mnemonic

Answer 18

Dear - domain
Kanye - kingdom
Politely - phylum
Came - class
Over - order
For - family
Grape - genus
Soda - species

Question 19

Development of classification over time

Answer 19

Technology has allowed us to understand genetic and chemical processes in organisms
By comparing RNA sequences, Carl Woese proposed to make domains due to differences between organisms in prokaryote kingdom

Question 20

Selective breeding method

Answer 20

Select ones with best characteristics you’re after
Breed them with each other
Select best of offspring and breed them together
Continue over several generations until all offspring have best characteristics

Question 21

Selective breeding advantages

Answer 21

Produces organisms with desired characteristics (more livestock)
Useful in medical research

Question 22

Selective breeding disadvantages

Answer 22

Reduces gene pool (inbreeding can lead to harmful genetic defects)
Can be seen as unethical
Not much variation so less chance of resistant alleles present if a new disease appears

Question 23

Plant tissue culture process

Answer 23

Remove several small pieces of tissues
From tissues in growth medium contains nutrients and growth hormones. Done in sterile conditions
As tissues produce shoots and roots, they are move to potting composers carry on growing

Question 24

Animal tissue culture

Answer 24

Sample of tissue is extracted from organism
Cells in sample are separated from each other using enzymes
Placed in a culture vessel and bathed in a growth medium contains all nutrients required to grow and multiply
After multiple rounds of cell decisions, cells can be split up again and placed in separate vessels to grow more
Once tissue culture is grown, can be stored for future use

Question 25

Genetic engineering definition

Answer 25

Altering an organism’s genome to introduce desirable characteristics

Question 26

Restriction enzymes purpose

Answer 26

Recognise specific sequences of DNA and cut DNA at these points.
Leaves pieces of DNA with sticky ends where they’d been cut

Question 27

Ligase purpose

Answer 27

used to join two pieces of DNA together with their sticky ends

Question 28

Recombinant DNA definition

Answer 28

Two different bits of DNA stuck together

Question 29

Vectors in genetic modification method

Answer 29

DNA wanted to insert is extracted using restriction enzyme
Vector DNA is acquired the same way
Vector DNA and wanted DNA is left with sticky ends and combined using ligase enzyme to make recombinant DNA
This is inserted into other cells e.g. bacteria so it is produced e.g. insulin

Question 30

Advantages of genetic engineering

Answer 30

Give organisms desired genes e.g. herbicide-resistance

Genetically engineer bacteria to produce importance substances e.g. insulin

Question 31

Genetic engineering disadvantages

Answer 31

Transplanted genes may get out into environment e.g. herbicide-resistance to weeds
May cause animals to suffer from health problems when modified

Question 32

GMO crops with insect-resistance method

Answer 32

Bacillus thuringiensis produces a toxin (Bt toxin) that kills insect larvae
Gene for Bt toxin is extracted from bacteria and is inserted into crops
This only kills specific pests and is harmless to humans (long term exposure isn’t known)
Insects with constant exposure to toxin may gain resistance

Question 33

GMO food production worries

Answer 33

Countries may become dependent on companies who sell GM seeds
The soil maybe too poor for anything to grow on
Poverty may be the problem of starvation

Question 34

GMO food production advantages

Answer 34

Crops can be produced to combat certain deficiency diseases (golden rice, more vitamin A)
Food production may be increased (resistances can prevent crops from dying, and increases yield)

Question 35

Other techniques to increase food production

Answer 35

Fertilisers

Biological control

Question 36

Fertilisers in increasing food production

Answer 36

Adds minerals needed in plant growth into soils so plants may grow
Excess fertiliser may damage ecosystem by going into rovers in lakes through eutrophication

Question 37

Biological control in increasing food production

Answer 37

Pests are controlled by introducing new predators into the ecosystem
has longer-lasting effect, but if miscalculated, can damage ecosystem (cane toads were introduced in Australia to combat beetles but are now pests themselves)