B6.5- Genetics and Evolution

Question 1

What did Mendel propose and list the time period as well.

When and why was Mendel’s work accepted after he died?

Answer 1

In the mid 19th century, Mendel carried out breeding experiments on plants and one of his observations was that the inheritance of each characteristic was determined by ‘units’ that are passed unchanged to each descendant.

-In the late 19th century, the behaviour of chromosomes during cell division was observed and in the early 20th century, it was observed that chromosomes and Mendel’s ‘units’ behaved in similar ways that led to the idea of these units, being gametes, were located on the chromosomes

Question 2

What were Lamark’s ideas? Give an example.

Answer 2

His idea was based on how changes that occur in an organism’s lifetime can be inherited so if an organism used a lot over a lifetime, the feature would develop and grow and if it’s any useful changes that took place- they would be passed down on to the offspring.

Eg- giraffes use their necks a lot to reach for higher leaves and trees and hence their necks would grow a little as a result and as this is a useful development, he proposed that the offspring of these giraffes would have long necks as well.

Question 3

What were Darwin’s theory?

Answer 3

He proposed a theory of evolution by natural selection so this is when individuals in a species showed a wide range of variation and this variation is a result of differences in their genes cause by random mutations that can be inherited, leading them to have that characteristic as a survival advantage and breed more successfully.
-When they breed, they pass on the characteristics that enabled them to survive in to the next generation

Question 4

What are the 2 factors Darwin’s rule is based on?

Answer 4

1) Darwin proposed a theory that would require genetic mutation that naturally occur in the DNA to introduce variation and more alleles that may become advantageous as the environment changes.
2) His rule is based on how organisms will produce more offspring than needed but the population remains stable as the organisms that inherited the characteristic most suited for their environment leads for them to be the ‘survival of the fittest’ and more likely to survive.

Question 5

Why do we still learn Lamark’s theory though it is wrong?

Answer 5

Because science is always changing and theories are always evolving. Theories are developed by looking back at other theories.

Question 6

What was Wallace’s theory?

Answer 6

Formation of new species through the process of speciation.

Question 7

Define species

Answer 7

A group of organisms that can interbreed to produce fertile offspring

Question 8

how can new species arise? (3)

Answer 8

New Species arise as a result of:

1) isolation: where two populations of a species became separated.
2) genetic variation between the populations.
3) speciation: when the populations become so different, that successful interbreeding is no longer possible to produce fertile offspring

Question 9

Give 3 ways a species can become isolated?(3)

Answer 9

1) geographically isolated- species become isolated due to mountains, sea, dessert, etc.
2) ecologically isolated - not a physical barrier but species can choose to be in diff habitats which can result in them becoming different species due to obtaining different characteristics
3) reproductively isolated- failure of gametes to fuse, different courtship behaviour.

Question 10

when does speciation occur?

Answer 10

-Populations of the same species become so different that they can no longer successfully interbreed to produce fertile offspring free can

Question 11

What is Wallace more commonly known for?

Answer 11

-More popular for warning colours are used by some species( eg butterflies) to deter predators from eating them and this was a beneficial characteristics that had evolved by natural selection.

Question 12

How is Wallace linked to Darwin?

Answer 12

-Wallace independantly came up with the idea of natural selection and published work on the subject together with Darwin in 1858 and this promoted Darwin to publish ‘On The Origin Of Species’ in 1859.

Question 13

What are fossils?

Answer 13

-remains of plants and animals and are found under rocks. They provide the evidence as to how much or how little organisms have evolved over time.

Question 14

What are 3 ways fossil form?

Answer 14

1) From gradual replacement by minerals:
- as things like teeth, shell, bones dont decay easily and can last a long time when buried. They’re eventually replafced by minerals as they don’t decay forming a rock-like substance and the surrounding sediments also turn to rock but the fossil stays distinct inside the rock and eventually it’s dug up.

2) Casts and Impressions- fossils are formed when an organism is buried in a soft material like clay and clay haters around it and the organism decays, leaving a cast of itself.

3) Preservation- in places where no decay happens.
- In amber and tar pits, there;s no oxygen or oisture so decay microbes can’t survive.
- In glaciers, it’s too cold for the decay microbes to work.
- Peat bogs are too acidic for decay microbes.

Question 15

What are the 4 methods of evidence we have for evolution?

Answer 15

1) Fossils- comparing physical characteristics to find similarities and diffs with modern day structures.
2) Comparative anatomy- gives evidence by looking at the structure of the living organisms if we have a common ancestor and comparing simil and diffs
3) Proteins.
4) Genomes- sim and diff between genetics and a way of determining common ancestors that a modern day organism evolved from.

Question 16

What is a common ancestor?

Answer 16

The origin of two species so the more similar genetic( and phenotypic) traits there are, the more closely related the organisms are and hence the more recent common ancestors they will have.

Question 17

What is the process of a fossil formation?(4)

Answer 17

1) Animal or plant dies.
2) Organism is buried very quickly in conditions where slow decomposition will occur- cold anaerobic condition to not allow bacteria to develop due to lack of oxygen eg bogs, rivers.
3) Bone is replaced with rock- mineralisation occurs and this process occurs at high temps and pressures and the bones wll be compressed and replaced by minerals, making fossils.
4) Tectonic activity or erosions brings fossil to surface

Question 18

Give reasons why not everyone agreed with Darwin?(3)

Answer 18

1) It was controversial as it went against common religious beliefs on how life on Earth developed as it disapproved God created the Earth.
2) Darwin could not explain as to how these new, useful characteristics appeared or even how they were passed on from individual organisms to their offspring and didn’t know anything about genes or mutations.
3) Wasn’t enough evidence to convince many scientists because not many other studies had been done into how organisms change over time.

Question 19

How can bacteria evolve to become antibiotic resistant?

Answer 19

Bacteria sometimes develop random mutations in their DNA which can lead to changes in the bacteria’s characteristics and this can lead to antibiotic-resistant strains forming when coming in contact with antibiotics, as the gene for antibiotic resistance becomes more common in the population as fewer people will be immune to the bacteria.

Question 20

To prevent more resistant strains of bacteria developing, describe 3 ways to stop?

What’s the problem with developing new antibiotics?

Answer 20

1) doctors should not prescribe antibiotics inappropriately, such as treating non-serious or viral infections
2) also important that patients finish this course of medicine every time to make sure all the bacteria are killed by the antibiotics so none survive to mutate and form resistant strains
3) Restrict the agriculture use of antibiotics to prevent the spread of antibiotic resistance from animal to human pathogens.

Development of new antibiotics is costly and slow and it’s unlikely to keep up with the emergence of new resistant bacteria.

Question 21

What bacteria is resistant to antibiotics?

Answer 21

MRSA is resistant to antibiotics

Question 22

What precautions can hospitals take to reduce the spread of bacteria? (3)

Answer 22

1) medical staff should wash their hands with soap and water or use alcohol gel between patients visits and wear disposable clothing that is regularly sterilised.
2) patients who become infected with antibiotic-resistant bacteria should be looked after in isolation from other patients.
3) visitors to hospitals and care homes should wash their hands as they enter and leave

Question 23

How have all living things be classified?

Answer 23

Traditionally living things have been classified into groups depending on their structure and characteristics in a system developed by Carl Linnaeus.

Question 24

How did Linnaeus classify things? How are organisms named?

Acronym for the system?

Answer 24

Linnaeus classified living things into kingdom, phylum, class, order, family, genus and species.
Organisms are named by the binomial system of genus and species.

Dirty Kinky Penguins Can Only Fly Going Sideways.

Question 25

What do we use to commonly refer to organisms? (2)

Answer 25

Genus and Species.

Question 26

What are the rules for organisms being named? (3)

Answer 26

In the binomial system, every organism is given its own two-part Latin name. The first part refers to the genus that the organism belongs to and gives the information on the organism’s ancestors. It is written in capital.

2) The second part refers to the species and should be in the lowercase letter.

Also, the name should be written in italics and to write in italics, just underline the words.

Question 27

How did we used to classify organisms? (3)

Answer 27

Appearance, Anatomy and Physiology

Question 28

Give 4 modern ways as to how we might classify organisms?

Answer 28

1) Genetic- check their DNA and the similarity.
2) Evolution- common ancestory.
3) Biochemisty.
4) Behaviour.

Question 29

Why did the classification systems change over time; what has developed? (2)

Answer 29

Scientists developed more evidence of the internal structures of organisms due to technological advances such as improvement of the microscopes and through the understanding of biochemical processes progressed, new models of classification were proposed as we were able to find out more about the internal structures of the organism.

Question 30

Why do we classify organisms?(3)

Answer 30

• Recognise biodiversity.
• Allows the bionomial system to be used worldwide and that means that scientists in differet countries or who speak different languages all refer to a particular species by the same name- avoiding potential confusion.
• understand evolutionary and ecologically relationships.

Question 31

What did Carl Woese propose and how?

Answer 31

-The three domain system which in turn divided six kingdoms- he gathered evidence from new chemical analysis technique such as RNA sequence analysis and how different cells reproduce, he found out that in some cases, species though to be closely related in traditional classification system as not as closely related as first though.

Question 32

What were the 3 domain systems?

Answer 32

1) ARCHEA- organisms in this domain are thought to be primitive bacteria but they’re actually a different type of prokaryotic cell. They were first found in extreme places such as hot springs and salt lakes.
2) BACTERA- domain contains true bacteria like E.cocli and although they often look similar to Archea, there are lots of biochemical differences between them.
3) EUKARYOTA- domain includes a broad range of organisms including fungi, plants, animals and protists.

Question 33

What do evolutionary trees show?

Answer 33

Evolutionary trees show how scientists think different species are related to each other and there can be evolutionary links beteen different organisms when brances come together, they will have a common ancestor and the more closely related the species will be so more characteristics they’re likely to share.

Question 34

What types of data can scientists use to work our evolutionary relationships- for living and for extinct?

Answer 34

Living organisms- they use the current classification data.

Extict species- they use information from the fossil record.

Question 35

What are the 6 kingdoms?

Answer 35

Plants, Animals, Protists, Fungi, Archaebacteria, Eubacteria.

Question 36

The habitats of Indian and green peafowl species do not overlap in the wild. Describe the order of events that may have led to the Indian and green peafowl evolving into two separate species (4)

Answer 36

The two popualtions of peafowls may have been isolated(1)
This would have led to genetic variations in each pop(1)
Over time, natural selec would have occured in the diff enviro, leading to some alleles becoming more common in one population than another(1)
Eventually 2 populations become so diff that they couldn’t interbreed successfully (1)

Question 37

Some people who have diabetes have a mutation in the insulin gene. A mutation could swap one base triplet for another base triplet in the part of gene’s DNA sequence. Explain how such a mutation could make a person more likely to have diabetes (5)

Answer 37

Each triple codes for one amino acid(1)
and amino acids have to be joined together in a specific order to make a specific protein(1)
The base of the three replaced in the gene could code for a different amino acid to the original base of three bases(1)
which may prevent insulin folding in the correct shape(1)
This may prevent insulin from functioning properly(1) resulting in diabetes(1)

Question 38

The defect that causes FA is found in a section of DNA that does not code for a protein. Explain how a defect in non-coding DNA could cause a disorder such as FA. (2)

Answer 38

The defect could stop a gene from being expressed(1) so that a particular protein that is essential to the normal functioning of the body is not produced (1)

Question 39

The Indian male peacock has large colourful tail feathers that it uses to attract a female.

Using your knowledge, explain how peacock evolved to develop, large colourful tails. (4)

Answer 39

1) Peacocks within a population show variation in tail length and colour
1) The longer and more colourful a peacock’s tail is, the more likely that a female will choose to mate with it
1) The alleles for the longer and more colourful tail are more likely likely to be passed on to the next generation as they will successfully reproduce
1) so over time, the alleles would become more common, allowing peacock to evolve.