Evolution Flashcards
(192 cards)
1
Q
Define evolution
A
A process by which new types of organisms develop from other existing types of organisms
2
Q
Give some examples of evolution
A
- Amphibians evolved from fish
- Reptiles evolved from amphibians
- Birds and mammals evolved separately from reptiles
3
Q
Explain how the scientific method works
A
- Scientists form a hypothesis for the question
- The hypothesis is tested
- Scientists test the same hypothesis in different ways - if it is upheld for most of the test, it becomes a theory
4
Q
What are the main sources of evolutionary evidence?
A
- The fossil record
- Modification by descent and structural similarities
- Genetic similarities
- Biogeography
- Other (such as chemical evidence from proteins)
5
Q
What is a fossil?
A
The preserved mineralised remains of living organisms found in rock
6
Q
How are geologists able to date fossils?
A
They look at the chemical elements that the rocks contain. By dating the rocks, they are dating the fossils
7
Q
What kind of rock are fossils found in?
A
Sedimentary rock (rock formed from layers of water-borne sediments)
8
Q
What is the study of plant and animal fossils?
A
Palaeontology
9
Q
How do fossils suggest that evolution has taken place?
A
They bear little resemblance to organisms living today indicating that species have evolved over time
10
Q
When did life begin on Earth as a single-cell bacteria?
A
3.6 billion years ago (according to the fossil record)
11
Q
What two things can fossils suggest about the earth millions of years ago?
A
The climate and environment
For example:
Fish fossils founds on mountains indicate that the area was covered by water in the past
12
Q
What does the fossil record show us about organisms?
A
- How organisms have changed and developed over time
- Scientists look for differences in the ___ of body structures:
- Type
- Origin
- Function
13
Q
What is the difference between extinct and extant?
A
Extinct - fossil species
Extant - still alive today
14
Q
What is convergent evolution?
A
- When body structures are analogous
- Same function, different origin
- Slightly different structure
15
Q
Give some examples of convergent evolution
A
- Wings on:
- butterflies
- bats
- birds
- All three wing types serve the same function but each evolved independently of each other
- Have a slightly different structure
16
Q
When does convergent evolution take place?
A
When organisms not closely related living in different ecosystems evolve similar structures or features
17
Q
What is divergent evolution?
A
- When body structures are shared by related species
- Involves homologous structures
- These body structures were inherited from a common ancestor
- This is called modification by descent
18
Q
Name some examples of divergent evolution
A
- Bones in the forelimbs of a _____ are similar:
- cat
- frog
- bird
- lizard
- human
- All have:
- humerus
- carpal
- radius
- ulna
- Indicates a common ancestor
19
Q
What can result from divergent evolution?
A
- Vestigial Structures
- Small and poorly-developed
- no useful function today
- inherited from an ancestor
20
Q
Give TWO examples of vestigial structures
A
- Whales and some snakes that have pelvises and undeveloped hind leg bones though they have no hind limbs
- The human appendix
21
Q
What can modification of body plans refer to?
A
Either divergent or convergent evolution
22
Q
How is the embryo evidence for evolution?
A
- Similarities can be seen in the embryos
23
Q
During early embryonic stages of development, what do all vertebrate embryos have?
A
- A nerve cord which becomes a spinal cord
- A supporting rod (notochord) which becomes a vertebral column
- Gill slits
- Fish-like heart
- Fish-like kidney
24
Q
During the early stages of development of certain vertebrate embryos, which animals can one not tell the difference between?
A
- A fish
- A frog
- A chick
- A pig
- A human
25
What can **divergent evolution** also be known as?
Modification by descent
26
What does DNA code for?
The formation of protein molecules
27
What does DNA make up?
The genes that parents pass on to their offspring
28
How can we use DNA to show evolutionary relationships between different groups of organisms
By comparing similarities and differences between the DNA
29
Studies on _____ show show similaries in cell chemistry in a wide range of organisms
Cell proteins and nucleic acids
30
What indicates that DNA was inherited from common ancestors?
Close similarities in the DNA of different species
31
What occurs as a result of genetic similarities
Chemical similarities
Remember: DNA determines the chemical make-up of organisms
32
If organisms share certain **chemical** features, then...?
The organisms are related and the chemical features were inherited from a common ancestor
33
Give an example in two groups of organisms (great apes and humans) that share similar chemical features
* The specific proteins that are needed for human colour vision are exactly the same as those found in the great apes and monkeys that live in Africa and Asia.
This suggests that these species all evolved from a common ancestor.
34
A protein called _______ can be used as evidence for evolution in what way?
* Cytochrome C
* Organisms with identical Cytochrome C amino acids in the protein:
* bacteria
* fungi
* tuna fish
* silkworms
* frogs
* humans
35
1. Which two animals have identical Cytochrome C proteins?
2. Which animal differs from this by only one amino acid?
1. Humans and Chimpanzees
2. Rhesus monkey
36
Which protein besides Cytochrome C and the protein needed for human colour vision has also been studied as evidence for evolution?
Haemoglobin
37
Define **biogeography**
The study of the distribution of species
38
Give TWO examples of species whose **biogeography** supports evolution
* Most **Marsupials** live in Australia
* Six species of **baobab** in Magagascar and only one in Africa and one in Australia
* Madagascar is the centre of baobab evolution
39
Who was Lamarckism founded by? When was this person alive?
Jean-Baptiste Chevalier de Lamarck (1744 - 1829)
40
What are two GENERAL characteristics about Lamarck?
* He was the first evolutionist to publicly state his ideas on evolution
* His ideas were wrong
41
What did Lamarck believe that evolution was mainly due to?
**Acquired characteristics** being **inherited** as creatures **adapt** to their environment
42
Give an example of an explanation of evolution in terms of Lamarckism
Giraffes evolved long necks because each generation stretched further to access high leaves in the trees and that this **change in body shape was inherited** by the next generation.
43
Along with the _inheritance of acquired characteristics_, what else did Lamarck believe?
He thought orgnaisms could **develop new organs** or **change existing ones** depending on whether they were used or not
44
What one thing was Lamarck right about in terms of how evolution is driven?
The environment is important in causing changes in organisms
45
What theory did Darwin introduce?
The theory of evolution by natural selection
46
Explain how Darwinism says that natural selection could result in a new species
1. Organisms **compete** for resources (food, water, space)
2. Any variation within an organism that **favours** survival in a _particular environment_ would increase its chances of reproducing
3. Organisms with **less favourable** characteristics are less likely to reproduce
4. More favourable variations are **passed on** to future generations
5. As **number of variations increases**, a new species could results
47
What is the opposite of punctuated equilibrium? Explain this concept.
* Gradualism
* This is the former theory that evolution occurred gradually and slowly over time
48
Explain the concept of puntuated equilibrium
* Gaps in the fossil record indicated that evolution was not a gradual process
* Evolution occurs in sudden bursts after long periods of no change
* Occurs in big jumps rather than in small steps
* Climate changes which happen every few thousand years, can play a part in this.
* Species that cannot adapt to the changes fast enough become extinct
* Species that adapt to the changes evolve
49
Who proposed the theory of evolution by punctuated equilibrium and when?
**Niles Eldrege** and **Stephen Jay Gould** in *_1972_*
50
Give another term for artificial selection
Selective breeding
51
How do humans act as an agent for evolution?
* Through artificial selction
* Animal breeders change the characteristics of animals by breeding animals that have the desired qualities
* racehorses
* cows
* pigs
* chickens
52
What characteristics have crop species been artificially selected for?
* fragrance
* drought resistance
* yield
53
Our major crop plants have been...
Artificially selected from their wild ancestors
54
What kind of plant does the maize that we eat today come from? Where is this plant originally found?
* Teosinte plant
* Indigenous to Mexico
55
What is the difference between the ancestor of and the maize that we eat today?
56
How was maize developed by artificial selection?
1. There are **variations** in the population
2. The **plump seeds** are collected and planted
3. These plants **carry more alleles** for plumper kernels.
4. Seeds from **plumpest** of these are collected**.**
5. These carry even more alleles for plump seeds and eventually the **frequency of the allele for the characteristic that you want increases**
57
What are some disadvantages of artificial selection?
* Removes a lot of variation in the population
* Prone to diseases
* Changes in environment could be problematic
* The whole of an artificially selected species (such as maize) could get a disease and become extinct
58
Explain the process of evolution by natural selection
* **Variations** are present in a population
* Passed from **parents to offspring**
* Variations that favours survival of an organism would **increase its chance of successfully reproducting** and passing on its genes
* In time, **these individuals will outnumber** individuals of the same species with less favourable variations
* Over time, as the number of individuals with favourable vatiations increases, a **new species** could result
59
What are variations?
Variations are the **result of small changes** in the **genetic make-up** of individuals of the **same species.**
60
What are variations the result of?
* Mutations
* Sexual reproduction (crossing over during meiosis)
61
The bigger the gene pool, the ...
more variations (genetic differences) in a species
62
Give some examples of certain favourable variations
* Variations enabling an organism to:
* Resist disease
* Outrun predators
* Survive unfavourable environmental conditions (drought or climate change)
63
Which process drives evolution?
Natural Selection
Nature selects individuals with favourable variations by eliminating those with unfavouable variations.
64
Define an adaptation
Any change in the structure or function of an organism that allows it to live successfully in an environment
65
What are traits that have been selected by natural selection?
Adaptations
66
Do adaptations develop because of the environment?
No.
It is organisms that have favourable traits that survive and pass this variation onto their offspring. The organisms with unfavourable traits die.
67
What is selection pressure?
When **environmental factors determine** whether an organism has **suitable variations** to survive or not
68
What is continuous variation?
Continuous variation shows a characteristic of any species that changes gradually over a range of values
69
Give some examples of characteristics in humans which are typical of continuous variation
* Height
* Weight
* Foot length
70
What is discontinuous variation?
A characteristic of any species with a limited number of possible values
71
Give some examples of discontinuous variation
* Gender
* Blood Group
* Eye Colour
72
Define a species
A group of organisms that are able to reproduce and produce fertile offspring
73
Do organisms have a look similar to be a species?
No.
They are a species as long as the are able to reproduce
74
Can you apply the species concept to organisms that reproduce asexually?
It is difficult to do this.
75
Define speciation
The process by which new species form
76
All evolutionary changes in species are due to \_\_\_\_\_
Genetic changes (changes in an organism's DNA)
77
In any population, there are several _____ that code for a particular characteristic.
Alleles
78
What is the _frequency of different alleles in a population_ defined as?
The proportion of a particular allele of a gene relative to the other alleles of the same gene
79
What does the frequency of all the different alleles added together in a population equal?
1
80
What happens when the frequency of certain alleles in a population changes over time?
A new species forms
81
What is it called when two genetically different parents mate? What kind of organism do they form?
Hybridisation forming a hybrid organism
82
Is a hybrid organism a different species to its parents?
Yes. It is classified as a new species
83
Is hybridisation more common in plants or in animals?
Hybridisation is more common in plants than in animals.
84
Give an example the process of one hybridised **plant** species forming.
***Peppermint***
*Watermint* x *Spearmint*
85
In **South Africa**, people are most concerned about the hybridisation of the _____ species. This happens when...
* Hybridisation of antelope species
* Occurs when species are introduced into areas that are outside their natural ranges
86
Give some examples of animals in South Africa that are commonly hybridised
* Blue Wildebeest x Black Wildebeest
* Burchell's zebra x Hartmann's zebra
* Bontebok x Blesbok
* Red hartebeest x Tsessebe
87
What is the main cause for speciation?
Geographic Isolation
88
What factors causes speciation to occur most of the time?
When populations are **physically** or **geographically** separated from one another.
89
What differs slightly in two isolated habitats?
Ecological (environmental) conditions
90
What two things, most of the time, isolates two populations from each other?
* A mountain
* The sea
91
What happens to isolated populations under different environmental conditions?
The two populations evolve
92
Give some examples of characteristics that change by natural selection over many generations
* Body Shape
* Food preferences
* Reproductive patterns
93
How are new alleles formed in a population?
Over multiple generations, **random mutations** take place
94
Geographic isolation can change the _______ in populations leading to the formation of a new species
Frequency of alleles
95
What would happen if the barrier separating two species were to suddenly disappear
They would not be able to reproduce anymore - two new species would have formed
96
Explain how geographic isolation leads to speciation
1. Populations are physically or geographically separated from one another
2. Each of the isolated populations evolves under the different environmental conditions
3. Random mutations take place leading to the formation of new alleles
4. The fequency of alleles in the populations changes (This means two new species have formed)
97
What was the ship that Darwin travelled on?
Beagle
98
Where did Darwin travel to on *Beagle*?
He visited the **Galapagos Islands** off the coast of **Ecuador** in **South America**
99
What was common between the 13 species of Darwin's finches?
They all had a common ancestor
100
Name the different kinds of finches that evolved
1. Ground finches (find food on ground or shrubs)
2. Tree finches (feed on insects)
3. Finches with stout beacks (eat seeds)
4. Finches adapted to eating insects or nectar
5. Beak like a woodpecker (uses cactus pine to dig out insects)
6. Finches that looks more like a warbler
101
What kind of breeding environment did the finches have on the Galapagos Islands?
* No predators
* No competetors
102
What else, besides Geographic Isolation, can cause speciation?
Reproductive isolation
103
Define reproductive isolation
Reproductive isolation is a means of stoppping two or more populations from exchanging genes during reproduction
104
Name SIX ways in which reproductive isolation can occur
* Temporal isolation
* Behavioural isolation
* Mechanical isolation
* Ecological isolation
* Gametic isolation
* Sterile or infertile offspring
105
Does evolution have to take millions of year to occur?
No. It can happen very quickly
106
In which types of organisms does evolution occur the quickest?
Organisms with very short life cycles such as:
* Bacteria
* Insects
* Viruses
107
What does DDT stand for
dichlorodiphenyltrichloroethane
108
How have mosquitos developed resistance to DDT?
1. A few are resistant to DDT
2. These mosquitos survive
3. A whole new population of DDT resistant mosquitos develops
4. The allele that breaks down DDT is now established in the population
109
Why has DDT been banned in most countries?
* It accululates in the tissues of organisms
* Causes extensive harm to animals further up food chains (including humans)
110
What is a pathogenic organism?
A disease-causing organism
111
What can happen when doctors prescribe drugs to get rid of pathogenic organisms?
The pathogenic organisms become resistant to drugs and undergo evolution by natural selection in a very short time.
112
The bacteria causing _____ keeps evolving resistance to the antibiotics used to treat the disease. What needs to be done about this?
TB
New drugs needs to be generated all the time to be effective against the new anti-biotic resistant bacteria
113
What is HIV?
A virus
114
HIV drug resistance occurs in the same way as...
Drug resistance in bacteria
115
Most HI viruses will be destroyed by anti-retroviral drugs but some have...
Genes that make them resistant to the drugs (which thus allow them to survive)
116
What happens to the HIV that survive the anti-retrovirals?
The replicate to form new, drug-resistant populations of HIV.
117
Which seeds (large or small) are more abundant in wet years
Small seeds are abundant in wet years
Larger (and tougher) seeds are more abundant in drought years
118
What is the changes in bill sizes according to wet or dry years an example of?
Fast evolution through natural selection
119
What is the study of **human evolution** using fossils and artefacts?
Paleoanthropology
120
What are artefacts
Objects such as tools and jewllery
121
What does it mean if a number of species share many features?
They are related by descent from a common ancestor
122
What kind of evolution is modification by descent from a common ancestor?
Divergent evolution
123
What explains why all vertebrates have the _same bones in their forelimbs_ and why all orchid flowers have the _same basic structure_?
Theory of common descent
124
Why did Darwin say that Africa is the most likely place to find the ancestor of humans?
It is where the great apes (the species most similar to us) live.
125
What is an alternative explanation to evolution?
Creationism
126
What are humans classified in?
The Order Primates
127
How many living species do the Order Primates consist of?
200 living species including:
* monkeys
* baboons
* apes
128
The apes are a group of primates including...
* Gibbons
* Orangutans
* Gorillas
* Chimpanzees
129
How long ago did the common ancestor that **all primates** evolved from live?
* About 30 million years ago
* You can refer to the phylogenetic tree on page 242
130
What shows that humans are related to apes and that their closest living relatives are chimpanzees?
DNA testing
131
Did humans come from chimpanzees?
No. Chimpanzees and humans both evolved from a common ancestor
132
Name three kinds of evidence for human evolution (evolution of living homonids from a common ancestor)
* Fossil evidence
* Cultural evidence
* Genetic evidence
133
Was the common ancestor of chimpanzees more like an ape or more like a human?
More like an ape
134
What characteristics do the fossils that fit between the common ancestor and modern humans have?
* Skeletons adapted for bepedalism
* Larger brain size
* Smaller face
* Smaller teeth
135
**Who** found the first fossil which filled the gap between the common ancestor and humans? **When** and **where** did he find it?
Professor Raymond Dart in 1925 at Taung (in South Africa)
136
**Who** found another fossil, after Raymond Dart, that also filled the gap between the common ancestor and humans? **Where** did he find it and **when**?
Dr Robert Broon at the Sterkfontein Caves (near Johannesburg) in 1945
137
Where else, after 1945, have many fossil fragments been found?
South Africa and East Africa
138
What can be used to compare the anatomy of two closely related species?
Fossils
139
What is a phylogenetic tree?
A diagram showing the relationship between **fossils**
140
What does the word "homonids" refer to?
Humans and their fossil ancestors
141
How many species of **homonids** lived in the past *6 million years*?
18 species
142
What part of a cell has its own DNA?
Mitochondria
143
What happens at fertilisation to the sperm's mtDNA and the egg's mtDNA?
The sperm's mitochondria stays outside the eff so only the mother's mtDNA is passed onto the offspring
144
What can happen each time mtDNA is copied?
A mutation can occur
145
What can be noted about the number of mutations of mtDNA occuring?
The number of mtDNA mutations occuring continues at a steady rate
146
How can mutations of mtDNA spread?
Within isolated populations, but not between populations
147
What does the number of differences in the mtDNA of two species tell scientists?
How long ago the species separated.
148
What can be noted about the mtDNA if the species separated recently?
1. If the species separated recently, there are few differences
2. If the species separated long ago, there are many differences
149
What is a cladogram?
A diagram comparing and showing the relationship between mtDNA.
150
What can confirm that the common ancestor for all apes and human lived about 15 MYA?
A cladogram
151
Cultural evicence of human evolution comes from studying...
Fragments such as:
* Sticks
* Burned bones
* Stone implements
* Pottery
* Jewellery
* Artwork
152
What are THREE key adaptations that enabled *Homo* to become expert at working with hands?
* Bipedalism
* Opposable thumb
* Broader, more sensitive fingers
153
Which THREE features of the skeleton does the ape have which the human does not have?
Brow ridge
Forelimb
Hindlimb
154
What are classified as homonids?
Humans and their anestor
| (Including the extinct upright apes)
155
Give FOUR characteristics of homonids
* Bipedalism
* Modification of hands
* Skull (Also, brain size and dentition)
* Language
156
Define bipedalism
Walking on two legs
157
Name SEVEN aspects that needed to be modified to allow for bipedalism
* Foot bone arrangement and size
* Pelvis size and shape
* Knee size and angle
* Leg length and angle
* Vertebral column shape and orientation
* Cranium shape
* Shoulder blades (Scapulas)
158
How must the foot bones be arranged to allow for bipedalism?
* The big toe must be aligned with other toes
* Other primates have an opposable big toe
159
How must the pelvis be shaped to allow for bipedalism?
The pelvis must be:
* Larger
* Shorter
* Broader
This allows it to support the greater amount of body weight passing through it.
160
What characteristics must the knee have to allow for bipedalism?
The knee joints must be:
* Enlarged
* Angled inwards
This allows them to bear increased weight
161
What characteristics must the leg have to allow for bipedalism?
* The femur ball must be:
* angled inwards towards pelvis socket
* strenthened
* Increase in leg length
* changes how muscles work
* allows humans to use natural swing of leg
162
How must the vertebral column change to allow for bipedalism?
The spinal column must change from straight to S-Shaped.
This gives it flexiblility.
163
How must the skull change to allow for bipedalism?
Foramen magnum shifted forward:
* Allows skull to balance on spine
* Allows eyes to look forward
164
How must the scapula change to allow for bipedalism?
Must become:
* Wider
* Straighter
This alllows for better upright posture
165
Why is bipedalism important?
* Frees hands for carrying things
* Improves vision
* Reduces body area exposed to sun
* Makes it easier for hunting and fighting
* Makes it easier to feed from bushes and low branches
* The increased height intimidates predators
* It is easier to carry offspring
* More energy-efficient way of moving (than swinging through trees)
166
Hands have evolved to make the following movements:
* Spreading fingers apart
* Cupping the hands
* Wrapping fingers around objects
* Opposable movement
167
The change in hand bones gave homonids...
* The precision grip
* The power grip
168
What did the precision grip and power grip allow for?
Unique cultural developments:
* Tool making
* Using tools
* Painting
169
How did language come about?
1. Skull enlarged (_facial bones - smaller_; _lower jaw - shorter_)
2. This made more space for larynx movement
3. Vocalisation developed (which then led to language)
170
State the OOA (Out Of Africa) Hypothesis
*Homo sapiens* first evolved in Africa (in Ethiopia or Sudan) and migrated from there round the world
171
How long ago did humans migrate into North Africa?
160 000 years ago
172
How long ago did humans migrate into South Africa?
120 000 years ago
173
How long ago did humans cross into the Middle East?
100 000 years ago
174
When did the second migration occur? What happened then?
85 000 years ago
*Homo sapiens* crossed into the Arabian Peninsula and from there migrated to China
175
Why did humans migrate?
* Humans followed migrating herds which was their food supply
* Competition for resources (space, food and shelter) could have forced the migration
176
Where were the oldest known fossils of the genus *homo* been found?
Africa
177
Transitional fossils between which two species are found only in Africa?
Transitional fossils that show intermediate stages between *H. ergaster* and *H. sapiens* are found only in Africa
178
What kind of evidence most strongly suppports the OOA hypothesis?
Genetic evidence
179
What confirms that all modern humans are descended from a single population of *H. sapiens* that probably lived in Ethiopia or Sudan?
DNA analysis
180
All modern humans are...
Very similar
181
What indicates that all humans evolved from a single region in Africa?
Comparisons of:
* Modern human chromosomes
* Nuclear DNA
* mtDNA
182
What shows that African people are the most ancient on Earth?
The cladogram
because African people have the most mtDNA mutations
183
What forms between continental plates that are moving apart?
A rift valley
184
What has exposed many of the hominid fossil sites?
The **East African Rift Valley** as it has grown deeper and wider over millions of years.
185
Label the skeleton of *Ardepithecus* in terms of ape-like and human-like features
186
Label the skeleton of *Australopithecus* in terms of ape-like and human-like features
187
Label the skeleton of *Homo* in terms of ape-like and human-like features
188
Compare the differences (tabulated) in anatomy of chimpanzees and humans
189
Tabulate FOUR differences between the skull and pelvis of the primates
190
Give reasons for the difference in the positions of the foramen magnum of the human and chimpanzee skulls
* Indicate differences in modes of locomotion
* Human
* centrally located
* allows for bipedalism (so that eyes look forward)
* Chimpanzee
* located at back of skull
* spine exits at an angle
Foramen magnum of *Australopithecus* is further forward than chimpanzee. Not as far forward as *H. sapiens*.
191
Why did Prof. Dart say that the Taung skull was intermediate between the common ancestor and humans?
* Foramen magnum was further forward than in chimpanzees
* Teeth were smaller than a chimpanzee's
* Palate was broader than a chimpanzee's palate
* Canines were smaller
* No gap between incisors and canines
* All these features were between chimpanzees and humans
192
TABULATE the differences between the three phases of human evolution.
Include:
* Age
* Adaptation to bepedalism
* How did it move
* Skull features
