B15-Genetics and evolution

Question 1

Who put forward the theory of evolution?

Answer 1

Charles Darwin
(Alfred Wallace)

Question 2

Why were Darwin’s ideas controversial?

Answer 2

They contradicted ideas of God
There was not enough evidence at the time
The mechanism of inheritance and variation were not known at the time

Question 3

What were Lamarck’s ideas?

Answer 3

Changes that occurred during the lifetime of an organism were passed onto offspring
If an individual continually repeated an action, the characteristic that allowed it to do this would develop further

Question 4

How was Lamarck’s theory proved to be wrong?

Answer 4

It was understood that changes caused by the environment were not passed on to sex cells`

Question 5

What is speciation?

Answer 5

The process of a new species developing through the selection of different alleles, which increases the genetic variation until the new population cannot breed with those in the old population to produce fertile offspring

Question 6

Who developed the theory of speciation?

Answer 6

Alfred Wallace

Question 7

Explain the process of speciation.

Answer 7

Variation exists within a population due to random genetic mutations
Alleles which provide a survival advantage are selected for through natural selection
Populations of species can become isolated, preventing them from interbreeding
Different alleles may be advantageous in different environments, leading them to be selected for
Over time, the selection of different alleles will increase the genetic variation between the populations
Eventually, the populations will no longer be able to interbreed to produce fertile offspring

Question 8

What is a species?

Answer 8

A group of individuals that can interbreed to produce fertile offspring

Question 9

What did Mendel experiment on?

Answer 9

Peas

Question 10

What were Mendel’s conclusions?

Answer 10

Offspring have some characteristics that their parents have because they inherit ‘hereditary units’ from each
One unit is received from each parent
Units can be dominant or recessive and cannot be mixed together

Question 11

Why was Mendel not recognised until after his death?

Answer 11

Genes and chromosomes were not yet discovered

Question 12

Give 2 places where evidence for evolution is found.

Answer 12

Fossils
Antibiotic resistance in bacteria

Question 13

What are fossils?

Answer 13

The remains of organisms from millions of years ago, which are found in rocks and ice

Question 14

How are fossils formed?

Answer 14

1. Parts of organisms that have not decayed because oxygen or moisture were not present, meaning that microbes that cause decay cannot survive
2. Parts of the organism such as teeth, shell and bones are replaced by minerals as they decay, forming a rock structure of the original part
3. Preserved traces such as footprints, burrows and rootlet traces remain due to the ground hardening around them and forming a cast

Question 15

What is the importance of fossils?

Answer 15

They can be used to show how the anatomy of organisms has changed over time
They can be used to compare how closely related two organisms are through looking at the similarities they have

Question 16

Why can’t fossils be used to show how life started on Earth?

Answer 16

Most early life forms are soft bodied and therefore decay completely, so there are few fossils of them
Any traces left have been destroyed by geological activity

Question 17

What is extinction?

Answer 17

When an entire species has died out

Question 18

What factors contribute to extinction?

Answer 18

1. Changes in environment which species cannot adapt fast enough to
2. New predators may have evolved or migrated to the area
3. A new disease arises and there are no alleles resistant to it
4. Competition for food
5. Destruction of habitat

Question 19

What are antibiotic resistant bacteria?

Answer 19

Bacteria which are not killed by antibiotics (which were previously used as cures against them)

Question 20

How does antibiotic resistance develop in bacteria?

Answer 20

Bacteria reproduce at a fast rate
Mutations during reproduction can result in new genes, such as the gene for antibiotic resistance, creating a new strain
Exposure to antibiotics creates a selection pressure, as those without the resistant genes die and the others survive
Those with resistance can reproduce and pass on the advantageous allele to offspring
This population of antibiotic-resistant bacteria increase

Question 21

What is an example of an antibiotic-resistant bacteria?

Answer 21

MRSA

Question 22

How can the development of resistance in bacteria be slowed?

Answer 22

1. Antibiotics should not be given for viral or non-serious infections
2. Specific antibiotics should be given for specific bacteria
3. Patients should complete their course of antibiotics - if they do not, some bacteria may survive and mutate
4. Antibiotics should be used less in agriculture

Question 23

How can the transmission of bacteria be slowed?

Answer 23

Maintain high levels of hygiene in hospitals
Medical staff and visitors should wash their hands regularly

Question 24

Who put forward the classification of organisms?

Answer 24

Carl Linnaeus

Question 25

What were the classes in the Linnaean system?

Answer 25

Kingdom Phylum Class Order Family Genus Species

Question 26

How does the binomial name work?

Answer 26

The first part of the name is the organism's genus and the second part is their species

Question 27

What was the level above Kingdom and who added it?

Answer 27

Domain Carl Woese

Question 28

What are the 3 domains?

Answer 28

Archaea: Primitive bacteria which live in extreme environments such as hot springs Bacteria: True bacteria Eukaryota: Organisms who have a nucleus enclosed in membranes