Evolution

Question 1

What was the common view at the time of Darwin

Answer 1

Most people in the UK believed that God created the world and all the living organisms in it. They also believed that the earth was only a few thousand years old.

Question 2

What happened in the 1830s to Darwin

Answer 2

He took part in a expedition abroad the HMS beagle around South America and the Galápagos Islands
He collected thousands of specimens of plants and animals and sent that back to the UK

Question 3

What is a feature of the specimens he collected

Answer 3

Some of these specimens were finches which he had collected on the Galápagos Islands
The finches showed variation in their characteristics
And Darwin proposed that their bent shape had evolved depending on the food that was available

Question 4

What were Darwin’s conclusions using his specimens

Answer 4

He concluded that the finches that had beaks that were more adapted for their food source, were more likely to survive, have more offspring and pass this characteristic on.

Question 5

What was happening around the same time as Darwin

Answer 5

Alfred Wallace was looking at animals and plants in South East Asia

Question 6

What was Wallace interested in

Answer 6

The evolution of warning colours and how new species form

Question 7

What did Wallace develop

Answer 7

A theory of evolution very similar to Darwin’s

Question 8

What did Wallace and Darwin do

Answer 8

He sent his ideas to Darwin for peer review and due to the similarity they co-presented the theory of evolution by natural selection

Question 9

Why was the theory of evolution controversial

Answer 9

As the common belief was that everything was made by God

Question 10

What are Fossils

Answer 10

The remains of organisms preserved in rock

Question 11

How do fossils provide evidence for evolution (1)

Answer 11

The older, deeper layers of rock contain fossils of simple organisms such as bacteria, whereas younger rock near the surface contain fossils of more recent and complex organisms such as mammals, so they support the idea that more complex organisms evolved from simpler organisms.

Question 12

How do fossils provide evidence for evolution (2)

Answer 12

By comparing modern day organisms with fossils we can also show that they share a common ancestor allowing relationships between extant and extinct animals to be investigated

Question 13

How do fossils provide evidence for evolution (3)

Answer 13

The sequence in which fossils are found also match their ecological links to each other with plants being found before animals as animals require plants to survive

Question 14

What are the negatives of the fossil record and why

Answer 14

The fossil record is incomplete, as the formation of fossils requires very specific conditions which are not commonly found and some organisms fossilise very rarely, and fossils can easily be destroyed by geological processes.

Question 15

What is comparative anatomy

Answer 15

It involves comparing the body structures of different species

Question 16

What are homologous structures

Answer 16

Bone structures that are similar in different organisms

Question 17

What do homologous structures show

Answer 17

They appear different on the surface but have the same internal structure, suggesting that they evolved from a common ancestor. However over millions of years as new species formed and evolved to live in different habitats the homologous structure adapted to serve different functions.

Question 18

What are neutral amino acids

Answer 18

Some amino acids are critical for a proteins function, whereas some can be substituted without having any affect on the protein called neutral amino acids

Question 19

What is comparative biochemistry

Answer 19

When we compare the amino acids sequences of the same protein that is found in different species

Question 20

How is comparative biochemistry used

Answer 20

The number of differences that exist are graphed against the rate at which the molecule undergoes neutral base pair substitution between them can then be used to estimate the point at which the species share a last common ancestor

Question 21

What is a feature of species that are more closely related to each other

Answer 21

They have more similar DNA and protein than species that are less closely related

Question 22

What is variation between species called

Answer 22

Interspecific variation

Question 23

What is intraspecific variation

Answer 23

variation between members of the same species

Question 24

What is a comparison between intraspecific variation and interspecific variation

Answer 24

Intraspecific variation is less pronounced than interspecific variation

Question 25

What are the two causes of variation

Answer 25

Genetic variation and environmental variation

Question 26

What is genetic variation caused by

Answer 26

The genetic material that na organism inherits.

Question 27

What is a mutation

Answer 27

Sometimes a change can take place in the DNA sequence of a gene this is called a mutation

Question 28

What occurs if a mutation affects a somatic cell

Answer 28

These mutations do not affect gametes and they are not passed on to offspring

Question 29

What is a feature of genetic variation

Answer 29

Genetic variation due to alleles applies to all organisms including those that reproduce by sexual or asexual reproduction

Question 30

How can genetic variation increase in asexual reproduction

Answer 30

Only by mutations

Question 31

How can organisms that sexually reproduce increase genetic variation (1)

Answer 31

1. They will receive alleles from two different parents, so they have a combination of features inherited from the two parents

Question 32

How can organisms that sexually reproduce increase genetic variation (1)

Answer 32

2. Each of the gametes is genetically different as during meiosis chromosomes are shuffled by independent assortment and genetic material is exchanged between chromosomes during crossing over and as the gametes are genetically different it causes genetic variation in the offspring.

Question 33

How can organisms that sexually reproduce increase genetic variation (3)

Answer 33

Fertilisation between the two gametes is a random process

Question 34

What can variation also occur due to

Answer 34

The environment

Question 35

What are most characteristics determined by

Answer 35

Both genetic and environmental variation

Question 36

What is discontinuous variation and how is it represented

Answer 36

Is also called discrete variation and is when a feature can only have a specific value and a bar chart is used to represent this data

Question 37

What is continuous variation and how is it represented

Answer 37

Features showing continuous variation can have any value within a range, this is called a continuum of values and is normally represented by a histogram

Question 38

What is anatomical adaptations

Answer 38

Are adaptations to the physical features of an organism

Question 39

What are behavioural adaptions

Answer 39

Are adaptations to how an organism acts or behaves

Question 40

What are physiological adaptations

Answer 40

Adaptations to how na organisms biological processes function

Question 41

What occurs in placental mammals

Answer 41

A foetus develops in the uterus and receives nutrients and oxygen from the mother via placenta. So when the offspring are born they reached a relatively mature state.

Question 42

What occurs in marsupial animals

Answer 42

The foetus leaves the uterus at a very early stage and continues its development in a pouch where it receives milk from the mother via placenta

Question 43

What is convergent evolution

Answer 43

Is when unrelated species begin to share similar traits

Question 44

What are analogous structures

Answer 44

Where different structures have adapted for the same function but have a different genetic origin

Question 45

What is continuous variation controlled by

Answer 45

Several genes working together called polygenes, and also due to environmental effects.

Question 46

What causes organisms to be adapted to their environment

Answer 46

Natural selection

Question 47

What do most organisms produce and what happens to them

Answer 47

A large number of offspring but the vast majority of these offspring do not survive

Question 48

Why do these organisms not survive and what are these factors called

Answer 48

Because food, water and space area ll limited. And many organisms are killed by predators or disease or by adverse weather conditions. And these factors are called selection pressures.

Question 49

What is the process of natural selection 1-2

Answer 49

1. Organisms within a species show variation in their characteristics that are caused by differences in their genes 2. The organisms who have advantageous alleles best adapted to a selection pressure have an increased chance of surviving and successfully reproducing. Less well-adapted organisms die or fail to reproduce “survival of the fittest”

Question 50

What is the process of natural selection 3-5

Answer 50

3.Successful organisms pass their advantageous alleles on to their offspring. Whereas non-advantageous alleles are less likely to be passed on 4. This process is repeated for every generation. Over time, the proportion of individuals with the advantageous adaptions increase 5. Over very long periods of time this process can lead to the evolution of a new species

Question 51

What can natural selection result in (negatives)

Answer 51

It can result in some insects being resistant to pesticides, plants to weedicides, and cause antibiotic resistance causing a negative impact on humans