Variation And Evolution

Question 1

What is continuous and discontinuous evolution

Answer 1

Continuous comes in a range eg height
Discontinuous comes in set groups eg eye colour

Question 2

What are 3 causes of variation

Answer 2

Genetic factors environmental factors and random genetic mutations

Question 3

Explain how mutation could lead to a rapid change in a species

Answer 3

Introducing a beneficial trait, provides a selective advantage, individuals with this mutation may have higher survival and reproduction rates resulting in a lineage of offspring with this trait, this is due to natural selection.

Question 4

What is speciation

Answer 4

The process by which new species from the original species

Question 5

Explain how you would know if 2 populations of one original species had become 2 new species

Answer 5

2 populations of the same original species can. Be considered as 2 new species if they have significant genetic differences and can no longer mate with each other to produce viable offspring

Question 6

How many years ago did simple life forms develop

Answer 6

More than 3 billion years ago

Question 7

What 2 sources of developing knowledge was used by Darwin

Answer 7

Fossils and observations

Question 8

Darwin was unable to explain how characteristics are passed onto offspring what explanation has since been found

Answer 8

Genetics, including Mendelian inheritance (how traits are passed on from parents to offspring) and the role of DNA

Question 9

What is a phenotype

Answer 9

The physical characteristics of an organism

Question 10

What is a genotype

Answer 10

The collection of genes and organism has

Question 11

Give 5 factors that can cause a species to become extinct

Answer 11

Habitat loss
Invasive species
Overexploitation
Climate change
Pollution

Question 12

Suggest how some hares evolved to have smaller ears than hares in warmer climates

Answer 12

Natural selection: in colder climates minimising heat loss is crucial for survival, hares with smaller ears may have been better suited to retain heat . Over time, individuals with smaller ears would have had a survival advantage, leading to their increased representation in the population through natural selection. This evolutionary process favoured the prevalence of smaller eared hares in colder climates demonstrating adaption to environmental conditions

Question 13

What is another name for selective breeding

Answer 13

Artificial selection

Question 14

What is selective breeding

Answer 14

Choosing plants/ animals with desirable traits and breed them together to make offspring with those traits over time, this can change the characteristics of the population, making the species better suited for human needs

Question 15

Suggest why dairy farmers use selective breeding

Answer 15

To increase milk production in cattle

Question 16

Describe how a breeder can achieve a litter of puppies with a gentle temperament

Answer 16

The breeder assesses the temperament of each dog in the mixed population, observing behaviour & reactions, dogs displaying desired traits will be chosen as breeding stock, chosen dogs are selectively bred pairing those with compatible temperaments to enhance the likelihood of producing gentle offspring. Puppies exhibiting gentle temperament are selected for further breeding whilst those with undesirable traits are not used. The breeder continues to selectively breed for gentle temperaments in future generations eventually resulting in a lineage of puppies with good temperament

Question 17

Suggest why puppies born from selective breeding are more susceptible to genetic defects

Answer 17

Due to inbreeding which increases the likelihood of harmful recessive genes being expressed; and lack of genetic diversity in the breeding pool, leading to the accumulation of genetic defects over generations

Question 18

Suggest why a new disease might be an issues for the puppies produced using selective breeding

Answer 18

Limited genetic diversity increasing susceptibility concentration of vulnerable traits amplifying the impact
Delayed response to develop resistance leaving them vulnerable initially

Question 19

Give 2 reasons why Darwin’s theory was controversial at the time it was published

Answer 19

It conflicts with religious beliefs particularly the idea of special creation described in religious texts such as in the Bible. Lack of direct evidence directly from fossil records therefore there was limited evidence directly documenting the transitional forms of evolution

Question 20

What was Lamarck’s theory

Answer 20

A characteristics which used more & more by by an organism becomes bigger and stronger and one that is not used eventually disappears, any feature of an organism that is improved through its use is passed to its offspring

Question 21

Give 2 examples of evidence that supports the theory of evolution by natural selection

Answer 21

Fossil records providing extensive evidence or the evolution of life over millions of years. Homologous structures, anatomical features that are similar in different species due to common ancestry

Question 22

Suggest 3 reasons why cats are selectively bred

Answer 22

To not cause allergies in humans, appearance, temperament

Question 23

Suggest one problem inbreeding causes

Answer 23

Genetic disorders eg blindness

Question 24

What does it mean to be in the same species

Answer 24

2 organisms share enough genetic material to reproduce and produce viable, fertile offspring

Question 25

Fill in the gaps
When dogs reproduce the _ produces sperm in the _
And the female produces eggs in the _
Sperm and eggs are also called _
During mating the sperm and egg fuse together this is known as _
Once this happens the _ starts to develop in the uterus of the mother

Answer 25

Male, testes, ovaries, gametes, conception, embryo

Question 26

Explain why puppies have characteristics of both parents

Answer 26

During sexual reproduction, puppies inherit genetic material from both parents through gametes. This combination of genetic information results in puppies possessing characteristics from both the mother and father

Question 27

How do fossils provide evidence for the theory of evolution

Answer 27

Through providing fossils of transitional forms between different species and succession of life forms revealing a chronological sequence of organisms with simpler forms founds in older layers and complex forms in younger layers

Question 28

Explain how jean baptise Lamarck accounted for the evolution of the long neck in giraffes

Answer 28

Lamarck believed the giraffes long neck results from generations of giraffes stretching their neck t o reach higher food sources, therefore evolved to have longer necks and have passed this trait onto their offspring. JBL theory was that a characteristic which is used more &more by an organism becomes bigger and stronger and one that isn’t used eventually disappears (regressive evolution)

Question 29

Explain why Augusts Weismann’s results did not support Lamarck theory

Answer 29

Because even after multiple generations of removing mice’ tails the offspring still had normal tails. To which he concluded traits acquired during an individuals lifetime, like a shortened tail, don’t get inherited by the next generation instead claiming that inherited traits are determined by genetic material not their environmental

Question 30

Explain how Charles Darwin accounted for the evolution for the long neck in giraffes

Answer 30

Because if giraffes with slightly longer necks existed in a place where lower plants were scarce, the giraffe with longer necks will have an advantage in reaching food in taller trees. This advantage increased their survival rate as they could access recourses that smaller necked giraffes couldn’t. As a result of this the longer necked giraffes were successful in reproducing and passed on these genes to their offspring, over time giraffes gradually shifted towards longer necks through natural selection

Question 31

Suggest an explanation for the evolution of the pigeon like ancestor into the flightless dodo

Answer 31

The flightless dodo evolved from its pigeon like ancestors due to:
absence of predators, with no predators there was reduced selection pressure favouring flight traits

Abundant food, plentiful ground based food sources favoured birds that could efficiently forage on the ground, birds investing less energy in flight and more in ground foraging were favoured by natural selection

Evolutionary trade offs, loss of flight was a trade off increased foraging efficiency and reduced energy use in the island environment

Question 32

Suggest why scientists are uncertain about the reasons for dodos extinction

Answer 32

Limited historical records and sparse scientific data contribute to the uncertainty surrounding the extinction of the dodo

Question 33

How do scientists know when extinct animals lived

Answer 33

Layers of rock containing fossils of early horses can be used to determine their age through biostratigraphy

Question 34

Suggest an explanation for the change in brain size in Homo sapiens

Answer 34

Natural selection favoured individuals with superior cognitive abilities, these larger brains enabled enhanced problem solving skills providing them with advantages, navigating complex environments leading to populations with larger brains with greater success in survival and hence higher reproduction rates and a gradual increase in average brain size within the species

Question 35

Give another explanation for long necks in the male giraffe

Answer 35

Sexual selection, particularly through male male combat and female mate choice may be significant drivers of the evolution of the long neck giraffe in male giraffes providing insights into the selective pressures shaping the giraffes long neck beyond traditional views centred on feeding adaptations

Question 36

When did Darwin publish his theory

Answer 36

24 November 1859

Question 37

How may new species arise due to isolation

Answer 37

Species may become isolated from each other so evolve independently

Question 38

Define the term extinction

Answer 38

The permanent disappearance of a species or group of organisms from the earth