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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

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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
What did Lamarck say about the inheritance of these characteristics?
Characteristics acquired in their lifetime were passed on to their offspring
25
Where did Darwin get evidence for natural selection?
Galápagos Islands
26
What were Darwin's two facts and the conclusion from this?
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
What was his third fact and what did he conclude from this?
There is variation between members of a species Those with particular variations will be more suited to survive an reproduce
28
What is meant by natural selection?
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
Summarise industrial melanism
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
What is speciation?
The development of new species
31
How can speciation occur?
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
What did Darwin study to show speciation?
Finches on different Galápagos Islands
33
What are fossils?
Preserved remains from a living organism
34
How can fossils be preserved?
In ice, amber, rocks, or bogs
35
What else can fossils be?
Imprints
36
Why is fossilisation rare?
The dead organism is usually eaten by a scavenger
37
What are the two methods of dating fossils?
Carbon dating | Potassium-argon dating
38
How does carbon dating work?
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
What is potassium-argon dating?
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
What is stratigraphy?
The study of layers in rock - new rock generally forms over old rock
41
What can skew stratigraphy?
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
What is a hominid?
An organism in the family Hominidae
43
What animals are hominids?
Humans, and great apes
44
When did humans and apes common ancestor live approximately?
5-7mya
45
What were the most important changes that happened as humans evolved?
An increase in brain size | Bipedalism
46
What is 'knuckle-walking'?
A style of movement using four limbs
47
What 4 pieces of evidence prove bipedalism?
``` Foramen magnum position Pelvis shape Femur / knee position Foot shape Vertebral column ```
49
What is the foramen magnum?
The hole in the skull where the backbone meets with the skull
50
Where is the foramen magnum in humans and how does this affect neck muscle?
At the bottom of the skull | The neck muscles are small and low down as the head is balanced on the backbone
51
Where is a gorilla's foramen magnum and how does this affect muscle?
At the back | Neck muscles are large and are high up
52
Describe the human's pelvis
Short and broad; basin shaped
53
How does the human's pelvis shape show bipedalism?
Organs are supported immediately above them
54
Describe the gorilla's pelvis
Long and narrow
55
Describe the human femur and how the location of the knees is advantageous
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
Describe gorilla's legs
They cannot straighten them | Knees bend outwards from the pelvis
57
Describe the human foot
Arched Big toe is parallel with the others Therefore the foot is adapted for walking
58
Describe gorilla's feet
Flat footed with an opposable big toe adapted for grasping
59
Describe human's vertebral column and how this proves bipedalism
2 slight curves to make an S shape | The head is directly above the centre of gravity
60
Describe the gorilla's vertebral column
Arched | Supports the weight of the body whilst knuckle walking
61
How can we tell the size of the brain?
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
Where and when did Australopithecines evolve?
Africa | About 5mya
63
Describe an australopithecine
Ape like head; flat face, flat nose, no chin, powerful jaws, walked upright but had a rolling gait
64
Lucy is a fossil of what Australopithecine species?
A. afarensis
65
When did A. afarensis live?
4-2.5mya
66
Explain how A. afarensis lived
In family groups Ate mainly plant food They had long arms and ape like wrists

AS Human Biology (4 decks)

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