y11 test4

Question 1

What is variation?

Answer 1

differences in the characteristics of individuals in a population

Question 2

What is interpecific variation?

Answer 2

variation between species

Question 3

What is intraspecific variation?

Answer 3

variation within species

Question 4

What characteristics are caused by our genes?

Answer 4

blood group
eye colour
natural hair colour
earlobe shape

Question 5

What characteristics are caused by the environment?

Answer 5

scars
tattoos
language
hair colour/length

Question 6

What characteristics are cause by a combination of our genes and the environment?

Answer 6

mass
sporting achievements
height
skin colour

Question 7

What 3 processes lead to genetic variation?

Answer 7

meiosis (random fertilisation & crossing over)
sexual reproduction
mutations

Question 8

What is evolution?

Answer 8

a change in the inherited characteristics of a population over time through a process of natural selection

Question 9

What was Jean Baptiste Lamarck’s theory about evolution?

Answer 9

Within a species, organisms all start off looking very similar. Some individuals change as a result of use/disuse of a body part, giving them an acquired characteristic. Their offspring then inherit their acquired characteristics and develop them further. Eventually, the environment will have directly affected individuals, changing the nature of the species

Question 10

What 3 things are needed for evolution to take place?

Answer 10

variation, selection, time

Question 10

What was Charles Darwin’s theory about evolution?

Answer 10

Within a species, there is always variation. A random, chance mutation occurs that alters the genotype and phenotype of some individuals. Those with the mutation have a survival advantage in that particular environment. Those individuals are more likely to survive, reproduce and pass on the gene for the desired characteristic. This is an inherited characteristic. Over time, the new phenotype becomes normal. This is called natural selection. Nature if effectively selecting the organism with the most useful genes

Question 10

Why didn’t people believe Darwin straight away?

Answer 10

His views opposed the church

Question 10

What does the theory of evolution state?

Answer 10

the species alive today have evolved from simple life forms that first developed more than 3 BILLION years ago

Question 10

What were Darwin’s main observations?

Answer 10

1) overproduction of offspring
2) numbers within a population stayed constant
3) variation exists between offspring
4) struggle for survival
5) survival of the fittest

Question 10

How can we prevent extinction?

Answer 10

• education
• reduce consumption
• stricter pollution laws
• increase renewable energy usage
• eat less meat and dairy
• captive breeding programs
• reduction of climate change

Question 10

What are some causes of extinction?

Answer 10

• illegal wildlife trade
• overfishing
• climate change
• pollution
• destruction of natural habitats
• population growth
• overconsumption
• predators
• disease

Question 10

How does mineralisation occur?

Answer 10

1) An organism dies and sinks to the bottom of the water
2) The organism becomes covered in sediment, the soft parts of the body decay and the sediment begins to turn to rock
3) More sediment settles, more organisms die and the sediment is compressed as more layers are added
4) Minerals replace the bone and the skeleton turns to rock
5) Rock layers become lifted up, they are eroded by wind and rain and faults in the rock expose the fossils

Question 10

How do genetics show evidence of evolution?

Answer 10

An understanding of DNA means we can see mutation leading to a survival advantage, leading to evolution

Question 10

How does speciation show evidence of evolution?

Answer 10

At the end of speciation, evolution must have occurred as offspring from different species cannot reproduce to give fertile offspring

Question 10

What is Wallace’s warning colouration?

Answer 10

Use of bright colour to deter predators- predators learned to avoid animals with these colourations as they are likely to cause injury, taste bad or be poisonous. He realised warning colouration must be passed on by natural selection.

Question 10

How do fossils show evidence of evolution?

Answer 10

• If two fossils are found in the same sediment layer we can assume they were alive at the same time
• If there is no change between the fossils in different layers, we can see that the species was well adapted to their environment (which didn’t change) so there was no need for evolution
• If a fossil disappears from a layer and all future layers, we can see when the animal went extinct
• If each layer shows a slightly different species, it suggests the species evolved over time. It is likely that the environment changed and natural selection occurred, changing the overall phenotype of the species which we can see in fossils. We can compare their anatomy to see how they evolved over time (simple –> complex)

Question 10

What is a fossil?

Answer 10

the remains of an organism that lived millions of years ago

Question 10

What is a species?

Answer 10

a group of organisms which have similar characteristics and can successfully breed with each other to produce fertile offspring

Question 10

What did Wallace discover

Answer 10

warning colouration and speciation

Question 10

Name 5 ways that fossils are formed:

Answer 10

Mineralisation
Preserved in ice
Preserved in resin/sap (amber)
Volcanic ash
Traces of footprint buried under sediments

Question 10

Why is the fossil record incomplete?

Answer 10

• not all specimens are in a suitable environment for fossilisation
• fossils could have been destroyed by natural disasters/ urbanisation
• not all of them may have been found
• not identified as fossils
• fossilisation process disrupted
• soft bodied organisms can’t be fossilised, only preserved in amber

Question 11

Why are hybrids often infertile?

Answer 11

their chromosome number is odd. meiosis halves the chromosome number, so meiosis can’t successfully take place

Question 12

How does speciation occur?

Answer 12

1) A population becomes geographically isolated from the original population
2) The new population is exposed to different environmental conditions
3) Mutations may occur, creating variation in the new population, so there will be new phenotypes
4) Natural selection occurs whereby the best adapted individuals in the new population survive and reproduce. Others won’t survive
5) Over a long period of time, the new population changes to the point where it can no longer interbreed with the old population to give fertile offspring
6) Speciation has occurred

Question 13

When was the structure of DNA determined?

Answer 13

mid 20th century