B13 Evolution and Classification

Question 1

What are the 2 types of variation?

Answer 1

Genetic and environmental variation

Question 2

Which of the following is not a form of environmental variation?: Yellow leaves, suntan, blue eyes

Answer 2

Blue eyes

Question 3

What does a mutation produce?

Answer 3

A genetic variant

Question 4

How can mutations lead to variation?

Answer 4

The gene becomes altered, so will code for a different amino acid, potentially leading to changes in the protein that it codes for, leading to phenotype changes.

Question 5

Why do most mutations not change an organism’s phenotype?

Answer 5

Most mutations have little to no impact on the protein being coded for.

Question 6

Summarise the theory of evolution by natural selection:

Answer 6

• Populations of a species show phenotypic variation due to genetic variants
• Some mutations give rise to characteristics that facilitate better survival
• The organisms with the variant are more likely to survive and reproduce
• Reproduction rate is higher among those with the desirable characteristics, and they become more prevalent in the population; the species evolves

Question 7

When does speciation occur?

Answer 7

When the characteristics of a group of organisms diverge so greatly from the initial population that they can’t interbreed

Question 8

List 3 ways in which a species could go extinct:

Answer 8

• A new predator wipes them out
• A disease wipes them out
• A catastrophic event occurs

Question 9

List 2 reasons why Darwin’s theory wasn’t fully accepted initially:

Answer 9

• Contradicted religious attitudes- removed need for a ‘Creator’
• No explanation for why characteristics arose

Question 10

Summarise Lamarck’s theory of evolution:

Answer 10

Changes in characteristics that an organism acquires over the course of its life are passed onto the offspring.

e.g. A rabbit’s legs may grow longer from running from predators, and the rabbit would pass that onto its offspring

Question 11

Describe the basic process of selective breeding (4 steps):

Answer 11

• Select organisms with desired characteristics
• Breed them with one another
• Breed the best of the offspring
• Continue the process to increase the prevalence of the characteristic

Question 12

What may dogs be selectively bred for?

Answer 12

A gentle temperament

Question 13

List 2 disadvantages of selective breeding:

Answer 13

• Reduces variety- lowers species’ ability to adapt to changes
• Increased risk of autosomal recessive disorders

Question 14

In genetic engineering, how is a desired gene isolated from an organism’s genome?

Answer 14

It is cut out with an enzyme.

Question 15

Where is the gene inserted after isolation in genetic engineering?

Answer 15

Into a vector, like a virus or bacterial plasmid, which is then introduced to the target organism

Question 16

Name one application of genetic engineering:

Answer 16

Used in insulin production for the treatment of type 1 diabetes- insulin genes are inserted into bacteria

Question 17

List 2 advantages of genetic engineering in crop production:

Answer 17

• Increased yield
• Crops can be engineered to contain essential nutrients

Question 18

List 2 disadvantages of GM crops:

Answer 18

• Long-term health effects are not known
• Affects number of wild flowers + insect population reducing farmland biodiversity

Question 19

Describe the process of tissue culture:

Answer 19

Plant cells are placed into a hormone-containing growth medium and form new, clone plants.

Question 20

Describe how animals can be cloned using embryo transplantation:

Answer 20

• Sperm cells are taken and used to artificially fertilise an egg cell
• The developing embryo splits before cells become specialised
• Embryo clones are implanted into animals and produce genetically identical offspring

Question 21

Describe the process of adult cell cloning:

Answer 21

The nucleus is taken from an unfertilised egg cell and replaced with that of an adult body cell. The egg cell is then stimulated using an electric shock so that it divides.

Question 22

List 2 benefits of cloning

Answer 22

• Can be used to preserve endangered species
• Produces many ‘ideal’ characteristics

Question 23

List 2 disadvantages of cloning:

Answer 23

• Reduced gene pool
• Potential health issues

Question 24

List 3 ways in which fossils form:

Answer 24

• Mineral replacement as remains decay
• Casts/impressions
• Preservation

Question 25

Why is peat so effective at fossil preservation?

Answer 25

The conditions are too acidic for the microbes that mediate decay.

Question 26

Why is there a lack of evidence on how life began on earth?

Answer 26

• It is believed that early organisms were soft-bodied (don’t fossilize)
• Primordial fossils may have been destroyed by tectonic activity

Question 27

What is a species?

Answer 27

Group of organisms that can mate and produce fertile offspring

Question 28

What is speciation?

Answer 28

The development of a new species

Question 29

List 2 steps leading to speciation:

Answer 29

• Isolation
• Natural selection

Question 30

Why can antibiotic resistance increase so quickly?

Answer 30

Bacteria reproduce rapidly, passing on the resistance gene to their offspring.

Question 31

List 3 ways of preventing the spread of antibiotic resistance:

Answer 31

• Reducing population usage of antibiotics
• Finishing full course of antibiotics
• Reducing use in agriculture

Question 32

Define mutation

Answer 32

A random change in an organism’s DNA

Question 33

Define selective breeding

Answer 33

Breeding organisms within a certain gene pool to increase the prevalence of ideal characteristics