B15 - Genetics & Evolution 2️⃣✅

Question 1

What were the 3 main things Darwins theory of evolution by natural selection proposed?

Answer 1

• Individual organims within a particular species show a wide range of variation & characterisics
• Individuals with characteristiscs most suited to the environment are most likely to survive and breed
• The characteristiscs that have enabled these individuals to survive are then passsed onto the next generation

Question 2

Give three reasons why Charles darwins theory of evolution by natural selection was only gradually accepted in the 1800s society in which it was released into

Answer 2

• The theory challenged the idea that God made all the animals and plants that live on Earth
• At the time there was insufficient evidence to convince many other scientists
• The mechanism of inheritence and variation was not understood/ known until 50 years after the original theory was published

Question 3

What was Jean-Baptiste Lamarck’s theory?

Answer 3

The theory of aquired characteristics
* That if an organism wanted something enough it would aquire the desired characteristic e.g. giraffe essentially wanted to reach leaves higher so stretched it’s neck to do so

Question 4

What is natural selection?

Answer 4

When the environment decides which genes/ characteristics are advantageous and allow for organisms to thrive & therfore breed to pass on the desired characteristic

Question 5

What determines organisms the same species?

Answer 5

If they can reproduce to produce fertile offspring

Question 6

How was lamarack’s theory proven wrong?

Answer 6

By the existence of modern genetics as we now know that aquired characteristics not affect the DNA sequence of the organism, and cannot be passed down from one generation to the next.

Question 7

What did Wallace do to contribute to the theory of natural selection?

Answer 7

As well as Darwin, he independently reached a very similar conclusion for evolution by natural selection as Darwin did + theorys revolving around speciation that we use today.

Question 8

Did Wallace & Darwin ever compare research?

Answer 8

Yes, they both presented a joint paper together, providing additional support to the theory.

Question 9

What did Wallace mainly contribute to revolving around speciation?

Answer 9

The evolution by natural selection and therfore speciation between organisms that are of very similar characterisitcs but have different phenotypes - different colours. Wallace was especially known for his work on colouration of species depending on their environement

Question 10

What is speciation?

Answer 10

When 2 organisms of the same species undergo changes (evolution) via natural selection that make them each so different that they can no longer reproduce to produce fertile offspring, therefore deeming them separate species

Question 11

What is the structure/ flow chart for Evolution by natural selection?

(can also be applied to answering questions)

Answer 11

Question 12

What three things did mendel test for in his experiments?

Answer 12

• Colour of pea pods
• Length of pea plant
• Colour of flowers

Question 13

What did mendel discover during his experimentation?

Answer 13

• Characteristics in plants are inhertited/ are determined by ‘heriditary units’
• Hereditary units are passed to offspring, unchanged, but one from each parent
• Heriditary units can be dominant or recessive (If both dominant and recessive, domainant will be expressed, you require 2 recessive allelels in order for the recessive characteristic to be expressed)

Question 14

Why was it that mendel’s work was only aknowledged/ used after his death?

Answer 14

Because in the 1800s they did not have any idea of chromosomes/ genes/ DNA

Question 15

When was mendel’s work realised to be correct/ the foundings for genetics?

Answer 15

In the early 20th century is was observed that chromosomes & mendells ‘units’ behaved in similar ways - This lead to the idea that the ‘units’, now genes were located on the chromosomes

Question 16

What causes speciation to naturally occur?

Answer 16

Changes in the natural environment/ separation of 2 groups of the same species due to an environmental change

Question 17

How does speciation work?

Answer 17

After separation, alleles for characteristics that enable the organisms to surive and breed sucsessfully in the new envrionment will be selected/ passed on. These alleles are going to be different from those that gave sucsess in the original envrioment as it would have been different. As a result of the selection of the new alleles the 2 separate populations would increase in genetic variation and change, so much so that they can no longer interbreed to produce fertile offspring, implying that a new species has formed and speciation has occured

Question 18

What is extinction?

Answer 18

When there is no remaining individuals of a species still alive

Question 19

What are 4 factors that contribiute to extinction of species?

Answer 19

• the environment changes too quickly and the species cant adapt in time so dies
• A new species/ predator kills them all or out competes them, starving them of resources
• A new disease comes and wipes them all out
• A catastrophic event occurs such as asteriod that wiped out dinosaurs

Question 20

What are the 3 main methods of fossilisaiton?

Answer 20

• Gradual replacement by minerals
• Casts + impressions
• Complete preservation (no decay at all)

Question 21

How does fossilisation by gradual replacement of minerals work?

Answer 21

When parts of an organism such as teeth/ bones decay very slowly and over time are replaced by minerals. Therefore leaving behind rock-like substances in the exact same shape & size of the organsim, but just made of rock/ mineral.

Question 22

How does fossilisaiton by cast + impressions work?

Answer 22

When an organism is burried in a soft mateiral such as clay, as the clay hardens, the organism decays, leaving behind a gap in the clay in the same shape/ size as the organism + impressions are when things such as footprints are preserved

Question 23

How does fossilisation by complete preservation work?

Answer 23

When an organism gets trapped in a material such as amber & it then hardens - due to the lack of oxgyen and moisture, the organism remains completly in tact and doesnt decay, perfectly and completly preserving the organism

Question 24

What are 4 places in which fossilisation by complete preservation of organsism can occur?

Answer 24

• Peat bogs
• Glaciers
• Tar pits
• Amber

Question 25

Why do the locations that allow for fossilisaiton by complete preservation due to no decay actually preserve the organism?

Answer 25

• Tar pits & amber do not have any oxygen or moisture in so microorganisms cant decay the organism
• Glaciers are too cold for microorgansims to decay anorher organism
• Peat bogs are too acidic for microorganisms to decay another organism

Question 26

Why do we not have any fossils/ remains of the 1st organisms that exited on earth?

Answer 26

• Because the early creatures on earth were soft-bodied so didnt have bones so would decay very quickly & easily without any remains as they didnt have bones/ teeth to fossilise
• And for earlier fossils they could have been destroyed

Question 27

How do bacteria develop resistance?

Answer 27

Just like all organisms, bacteria can sometimes undergo random mutation and because of their rapid reproduction rate can evolve rapidly as well. This can rarley gives them a characteristic that allows them to become reistant to the antibiotic. This bacteria would then rapidly reproduce by binary fission and form a resitant strain, causing the infected person to remain infected and require a new antibiotic to get rid of the strain

Question 28

What is an extremely resistant bacteria commonly refered to as?

Answer 28

A super bug

Question 29

What is a common bacteria than is resitstant to many different types of antibiotics?

Answer 29

MRNA

Question 30

What are the 3 ways in which we should reduce the development of antibiotic resistant strains?

Answer 30

• Doctors should not prescribe antibiotics inappropriately e.g. non-serious ilnesses or viral infections
• Patient should complete their prescribed course of antibiotics so that all the bacteria are killed and non surivive to mutate into resitant strains
• The use of antibiotics in agriculture/ farming should be restricted

Question 31

What is the mnemonic for remembering the classification system?

Answer 31

Dear
Kate
Please
Come
Over
For
Great
Spaghetti

Question 32

What is the classification system in order?

Answer 32

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 33

What is the binomal system?

Answer 33

Using the main classification system my Linneaus, a shorter way to identify a species - using just the Genus & species of animal to identify it

Question 34

What do you have to ensure whilst using the binomal classification system?

Answer 34

That the fist letter of the Genus is captial and that you write it in italics

Question 35

What are the three domains?

Answer 35

• Archea - primative bacteria in extreme environments
• Bacteria - true/ modern bacteria
• Eukaryota - protists, fungi, plants & animals (organsism with nucleus)

Question 36

Who added the Domain above kingdom to Linneaus’ classification system?

Answer 36

Carl Woese

Question 37

Why is latin used in the classification system?

Answer 37

Because its a dead language that no one speaks and therefore it can be understood across various different languages

Question 38

What are vertibrates?

Answer 38

Organisms with a spine

Question 39

What are invertibrates?

Answer 39

Organisms without a spine

Question 40

Who created the classification system we use today?

Answer 40

Carl Linneaus