Topic 4 - Natural Selection and Genetic Modification

Question 1

Evolution

Answer 1

the way that species develop by gradual changes over many generations due to natural selection

Question 2

natural selection

Answer 2

Organisms with the best genes and characteristics are more likely to survive, breed and pass on their better genes.

Question 3

competition

Answer 3

the fight to eat, survive and breed

Question 4

resistance

Answer 4

the natural ability of some members of a species to survive poisons that would kill the other members

Question 5

evolution of resistance

Answer 5

evolution of organisms that stops them from being affected by poisons

Question 6

antibiotic resistance

Answer 6

antibiotics are used to kill bacteria. some bacteria were naturally resistant, bred and passed on their resistance genes

Question 7

disadvantages of GMO

Answer 7

• over-selection: farmers focussing too much on breeding for one characteristic, don’t spot problems with other characteristics causing suffering.
• gene leakage: the concern GMOs could breed with wild relatives, enabling the modified genes to escape into the wild. This could have ecological impacts.
• resistance: the concern that in areas growing GMOs, insects simply evolve resistance.
• insulin: Insulin made by GM bacteria is not identical to human insulin, some suffer adverse reactions.

Question 8

genetic engineering

Answer 8

the process of changing characteristics of organisms by giving them genes from another organism. the organism receiving the DNA is said to be genetically modified (GM)

Question 9

artificial selection

Answer 9

when human select the organisms to breed with the best characteristics

Question 10

selective breeding steps

Answer 10

1. organisms with desired characteristic chosen by humans
2. breed together
3. identify the characteristic in the offspring and select them
4. breed from only the offspring that have the desired characteristic
5. repeat over several generations

Question 11

selective breeding advantages

Answer 11

• higher yield of a food or medicine produced by a plant or animal
• harmful traits, to the species or to humans, can be bred out
• resistance to known diseases can be selectively bred into crops and medicinal plants
• crops can be selectively bred to be harvested more easily (all at the same height)
• selectively bred organisms can grow more quickly if this trait is selected for
• genes and alleles of traits that are not necessarily useful now, may be selectively bred out of a species, and may become useful later down the line. For example a medicinal plant extract

Question 12

selective breeding disadvantages

Answer 12

• Selectively bred organisms will share very similar genes (same alleles) resulting in all the individuals being susceptible to a disease
• Selective breeding can lead to a reduction in the number of different genes and alleles (variety) within a species (reduce the size of the gene pool)
• As the gene pool is smaller, changes in the environment, may result in the extinction of a species as the species does not have the trait to survive
• Nature should be the only entity that should be deciding which organisms can survive and reproduce, not humans
• Inbreeding may result in a higher chance of a disease caused by a recessive allele being present
• Selective breeding takes many successive generations and may not be successful

Question 13

medical GMOs

Answer 13

GM bacteria are used to make inulin (for diabetes) and some antibiotics

Question 14

pros and cons of GM

Answer 14

quicker than selective breeding, can introduce more different characteristics, but it’s expensive

Question 15

domains

Answer 15

the three main groups of life: bacteria, archae, and eukarya

Question 16

bacteria

Answer 16

single-celled organisms with no nucleus

Question 17

archae

Answer 17

single-celled organisms with no nucleus

Question 18

eukarya

Answer 18

often multi-cellular organisms. includes plants, animals, fungi and protists

Question 19

Linnaeus’ classification system

Answer 19

organisms are ranked by their similarities (least to most):
kingdom > phylum > class > order > family > genus > species
as we move down towards species, there are fewer organisms within each group and they share more similarities (more closely related)

Question 20

what did Carl Woese develop

Answer 20

the modern system of classification with three domains due to genetic analysis

these domains are:
- Archaea (primitive bacteria usually living in extreme environments such as hot springs and salt lakes)
- Bacteria (true bacteria such as E. coli and Staphylococcus)
- Eukaryota (which includes protists, fungi, plants and animals)

These domains are then subdivided into the smaller groups previously used (i.e. kingdom, phylum, class, order, family, genus, species)

Question 21

Modern classification

Answer 21

Technological advances, such as DNA sequencing, have allowed scientists to classify organisms based on genetics rather than shape. DNA changes slowly over time, so we’re able to more accurately work out how closely species are related.

Question 22

how has genetic analysis led to the suggestion of the three domains rather than the five kingdoms classification method

Answer 22

The five kingdoms model was based mostly on visible features (morphology), while the three domains model is based on genetic and molecular evidence, which gives a more accurate picture of evolutionary relationships.

Question 23

stages of natural selection and evolution (VOSSUG)

Answer 23

Variation - in any population, there are differences between individuals in a species (caused by mutations)
Over-production/population - many organisms produce more offspring than necessary
Struggle for existence - there is competition for survival and resources between the organisms
Survival - those with helpful characteristics are more likely to survive to breed (survival of the fittest)
Useful alleles (characteristics) - are inherited by the offspring
Gradual Change - of the species over a period of time as useful characteristics are passed on to offspring

Question 24

Ardipithecus ramidus (Ardi) - how long ago + skull and face size

Answer 24

4.4 million years ago
small skull, large face

Question 25

Australopithecus afarensis (Lucy) - how long ago + skull and face size

Answer 25

3.2 million years ago small skull, small face

Question 26

Leakey's discovery of: Homo habilis/erectus - how long ago + skull and face size

Answer 26

1.6 million years ago large skull, small face

Question 27

restriction enzyme

Answer 27

an enzyme that cuts a specific sequence of DNA

Question 28

sticky ends

Answer 28

a strand of DNA with exposed bases

Question 29

vector

Answer 29

a molecule used to carry DNA into another cell

Question 30

DNA ligase

Answer 30

an enzyme that joins two molecules of DNA with a covalent bond

Question 31

steps for GMO

Answer 31

1. Identify and isolate the desired gene 2. The gene for the desired characteristic (e.g. insulin production) is cut out from DNA using a restriction enzyme. 3. This creates sticky ends – short, single-stranded sections of DNA at the ends. 4. A vector (usually a plasmid from bacteria) is also cut open using the same restriction enzyme. 5. This ensures the sticky ends on the plasmid match those on the gene. 6. The desired gene is joined to the plasmid using an enzyme called DNA ligase. 7. DNA ligase helps bind the sticky ends together to form a continuous DNA strand. 8. The recombinant plasmid (now carrying the desired gene) is introduced into host cells (e.g. bacteria). 9. The host cells divide and copy the new gene, producing the desired product (e.g. insulin).

Question 32

how can stone tool be dated

Answer 32

By looking at the structural features of the tool or fossil (e.g. simpler tools are probably older than more complex tools) By using stratigraphy (the study of rock layers). Older rock layers are usually found below younger rock layers, meaning that tools or fossils found in deeper layers are probably older) By using Carbon-14 dating (fossils contain carbon and stone tools are sometimes found along with carbon-containing materials e.g. a wooden tool handle)