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AS Human Biology > Chapter 9 - Where we fit in the world > Flashcards

Chapter 9 - Where we fit in the world Flashcards

1
Q

What is a species?

A

A group of similar organisms that have certain features in common

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1
Q

What are the features in common of a species?

A

Capable of interbreeding to produce fertile offspring

Biochemically and anatomically similar due to similar genes

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2
Q

How have new species developed?

A

Natural selection

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3
Q

What system is used to name organisms?

A

The binomial system

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4
Q

How are organisms written?

A

Genus species
e.g.: Homo sapiens
Italicised or underlined
Genus always begins with a capital letter

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5
Q

Why is the binomial system used?

A

It shows us whether organisms are closely related or not

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6
Q

What were old classification systems based on?

A

Observable features

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7
Q

What system do we use to classify organisms now?

A

Phylogenetic hierarchy

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8
Q

What does phylogenetic mean?

A

Organisms are placed in groups with other organisms that have close evolutionary relationships with them

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9
Q

What is the phylogenetic hierarchy?

A 
Kingdom
Phylum
Class
Order
Family
Genus
Species
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10
Q

What happens as you go down the hierarchy?

A

Increasing similarity between organisms

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11
Q

What is the binomial name for humans?

A

Homo sapiens (wise man)

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12
Q

What happens as you go up the hierarchy?

A

Increasing number of species in each group

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13
Q

What are 5 kinds of evidence used in classification?

A 
Biochemical
Anatomical
Embryological
Immunological
Behavioural
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14
Q

How are biochemical differences measured?

A

DNA hybridisation:
This involves taking two different unzipped strands of DNA and mixing them together
The more base pairings, detected by how much heat is needed to separate them, the more similar they are

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15
Q

What is the importance of the protein cytochrome c?

A

It has changed very little over millions of years and varies very little despite the huge range of Chordata it is found in

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16
Q

How is anatomy used in classification?

A

The more similar the anatomy, the more likely they are to be closely related

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17
Q

What does pentadactyl mean?

A

Five digits

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18
Q

Why are humans in the Primates order?

A 
We have opposable thumbs
Brachiation (180 arm swing)
Large brains
Stereoscopic vision
Nails
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19
Q

How are embryos used to classify?

A

The more similar embryos look in early development, the more closely related they are

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20
Q

How is immunological evidence gathered?

A 
Human serum is injected into a rabbit
The rabbit makes anti human antibodies
Serum is removed from rabbit
Human and new rabbit serum is mixed 
A precipitate is formed from the antigen antibody complex

This can be used with other animal serum to see relationships

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21
Q

Behavioural evidence?

A

Helps to see how closely related they are by looking for similar behaviour

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22
Q

What did Lamarck propose?

A

The power to change was a natural property of an organism

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23
Q

What caused the need for change in Lamarck’s view?

A

The environment - the changes occurred because of an ‘inner need’

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24
Q

What did Lamarck say about the inheritance of these characteristics?

A

Characteristics acquired in their lifetime were passed on to their offspring

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25
Q

Where did Darwin get evidence for natural selection?

A

Galápagos Islands

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26
Q

What were Darwin’s two facts and the conclusion from this?

A

All organisms over-reproduce
But, organism numbers in species remain roughly stable as a result of competition for resources

He concluded that there is a struggle for existence

27
Q

What was his third fact and what did he conclude from this?

A

There is variation between members of a species

Those with particular variations will be more suited to survive an reproduce

28
Q

What is meant by natural selection?

A

Any variation may be an advantage or a hindrance in the ‘struggle for existence’
Those with favourable variations will survive, reproduce and pass on their successful alleles
Those without will not survive, therefore will not reproduce and pass on its alleles

29
Q

Summarise industrial melanism

A

Pre-industry: speckled moth was only known species
Industry: 98% were melanic
This gave them an advantage as they could camouflage on tress covered in soot
These moths passed on their alleles

30
Q

What is speciation?

A

The development of new species

31
Q

How can speciation occur?

A

Geographical isolation:
- Different phenotypes are suited to different environments, so the different alleles will increase in frequency amongst themselves

  • Successful alleles caused by a mutation will be passed on, and will increase in frequency in the population
  • Genetic differences become so large that they can no longer interbreed to have fertile offspring - this is called reproductive isolation - so become different species
32
Q

What did Darwin study to show speciation?

A

Finches on different Galápagos Islands

33
Q

What are fossils?

A

Preserved remains from a living organism

34
Q

How can fossils be preserved?

A

In ice, amber, rocks, or bogs

35
Q

What else can fossils be?

A

Imprints

36
Q

Why is fossilisation rare?

A

The dead organism is usually eaten by a scavenger

37
Q

What are the two methods of dating fossils?

A

Carbon dating

Potassium-argon dating

38
Q

How does carbon dating work?

A

14C is present in CO2 in air
Therefore is eaten by animals via plants as they breathe it in
When animals die, no more 14C is incorporated
The half life of 14C to 12C is 5700 years
This can be used to date fairly recent fossils

39
Q

What is potassium-argon dating?

A

40K decays into 40Ar
The half life of 40K is 1.25bn years
This can be used to see how old a fossil is by stratigraphy

40
Q

What is stratigraphy?

A

The study of layers in rock - new rock generally forms over old rock

41
Q

What can skew stratigraphy?

A

Natural occurrences such as earthquakes, volcanic eruptions and fault lines can split/ bend/ tilt the rocks so they are not in chronological order, or by weathering and heavy rain

42
Q

What is a hominid?

A

An organism in the family Hominidae

43
Q

What animals are hominids?

A

Humans, and great apes

44
Q

When did humans and apes common ancestor live approximately?

A

5-7mya

45
Q

What were the most important changes that happened as humans evolved?

A

An increase in brain size

Bipedalism

46
Q

What is ‘knuckle-walking’?

A

A style of movement using four limbs

47
Q

What 4 pieces of evidence prove bipedalism?

A 
Foramen magnum position
Pelvis shape
Femur / knee position
Foot shape
Vertebral column
49
Q

What is the foramen magnum?

A

The hole in the skull where the backbone meets with the skull

50
Q

Where is the foramen magnum in humans and how does this affect neck muscle?

A

At the bottom of the skull

The neck muscles are small and low down as the head is balanced on the backbone

51
Q

Where is a gorilla’s foramen magnum and how does this affect muscle?

A

At the back

Neck muscles are large and are high up

52
Q

Describe the human’s pelvis

A

Short and broad; basin shaped

53
Q

How does the human’s pelvis shape show bipedalism?

A

Organs are supported immediately above them

54
Q

Describe the gorilla’s pelvis

A

Long and narrow

55
Q

Describe the human femur and how the location of the knees is advantageous

A

Straight and has a long neck to fit into the pelvis

Knees are directly under the the pelvis and they lock when leg is straight
This allows humans to stand for a long time without using much energy

56
Q

Describe gorilla’s legs

A

They cannot straighten them

Knees bend outwards from the pelvis

57
Q

Describe the human foot

A

Arched
Big toe is parallel with the others
Therefore the foot is adapted for walking

58
Q

Describe gorilla’s feet

A

Flat footed with an opposable big toe adapted for grasping

59
Q

Describe human’s vertebral column and how this proves bipedalism

A

2 slight curves to make an S shape

The head is directly above the centre of gravity

60
Q

Describe the gorilla’s vertebral column

A

Arched

Supports the weight of the body whilst knuckle walking

61
Q

How can we tell the size of the brain?

A

By pouring sand into the foramen magnum until it is full

It is then poured out into a measuring cylinder to find the volume; cranial capacity

62
Q

Where and when did Australopithecines evolve?

A

Africa

About 5mya

63
Q

Describe an australopithecine

A

Ape like head; flat face, flat nose, no chin, powerful jaws, walked upright but had a rolling gait

64
Q

Lucy is a fossil of what Australopithecine species?

A

A. afarensis

65
Q

When did A. afarensis live?

A

4-2.5mya

66
Q

Explain how A. afarensis lived

A

In family groups
Ate mainly plant food
They had long arms and ape like wrists

AS Human Biology (4 decks)

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