Natural Selection

Question 1

Natural Selection

Answer 1

Charles Darwin’s theory of natural selection proposed that all species have evolved from simple life forms that first appeared on Earth more than three billion years ago.

Question 2

Genetic variation

Answer 2

Different individual animals in a population (or species) have different combinations of genes (show genetic variation).

Question 3

Survival of the fittest

Answer 3

Individuals that are best adapted to the environment will have a greater chance of survival.

Question 4

Successful breeding

Answer 4

Individuals with the best chances of survival are the most likely to breed successfully (because they survive).

Question 5

Best characteristics survive

Answer 5

The characteristics responsible for the greater chance of survival are more likely to be passed on to the next generation.

Question 6

Charles Darwin developed his theory of evolution whilst

Answer 6

aboard the HMS Beagle on an expedition to the Galapagos Islands. He built up evidence to support the theory of natural selection and in 1859 he published his ideas in “On the Origin of Species”.

Question 7

Controversy around Natural Selection

Answer 7

At the time, Darwin’s ideas were met with significant opposition from the scientific community.

Question 8

Genes yet to be discovered

Answer 8

At the time, genes had not been discovered and Darwin was unable to suggest a method for the passing of characteristics between generations (from parent to child).

Question 9

Inconclusive evidence

Answer 9

There were scientists that regarded the evidence presented by Darwin as inconclusive.

Question 10

Religion

Answer 10

Natural selection challenged the common belief that God created the natural world.

Question 11

Alfred Russel Wallace

Answer 11

Most people think that Charles Darwin was alone in thinking about natural selection. In fact, Alfred Russel Wallace wrote to Darwin in 1858, expressing his similar thinking.

Question 12

Island research

Answer 12

Both had spent a significant amount of time on islands.
This decision helped their research on evolution because the isolation of island populations leads to enhanced speciation (the formation of new species) rates.

Question 13

Joint writings

Answer 13

1858, the two combined their great minds to produce joint writings.

Question 14

Competition

Answer 14

After the two had produced joint writings, Darwin accelerated the publication of ‘On The Origin of Species’ to be the first of the two to publish.

Question 15

It is a common misconception that

Answer 15

Darwin was alone in pioneering the thinking behind natural selection. In fact, Alfred Russel Wallace wrote to Darwin in 1858, expressing his similar thinking. This caused Darwin to accelerate the process of publishing his book.

Question 16

Impacts of the Theory of Evolution

Answer 16

Evolution is the gradual change of inherited characteristics of biological populations over time. It is usually driven by natural selection. The theory of evolution has greatly affected modern biology.

Question 17

Genetics

Answer 17

Scientists later discovered exactly how traits are inherited; through genes.
Genetics is now a huge area of biology

Question 18

Which area of biology wouldn’t exist without the theory of evolution?

Answer 18

Genetics

Question 19

Evolution and Speciation

Answer 19

Evolution is the gradual change of inherited characteristics of biological populations over time.

Question 20

The Evidence for Evolution

Answer 20

The discovery of genes as a mechanism (way) to inherit characteristics and create variance supported the theory of evolution.

Question 21

Antibiotic resistant bacteria

Answer 21

Natural selection neatly explains this phenomenon: Bacteria reproduce rapidly. Mutations occur during reproduction. If a mutated bacterium is resistant to antibiotics, it will survive exposure to antibiotics and go on to reproduce. This bacterium will represent the original ancestor of a new resistant strain.

Question 22

Fossils

Answer 22

Fossils show the gradual changes in organisms over vast periods of time.

Question 23

Resistant Bacteria
Bacteria reproduce rapidly. Mutations occur during reproduction. This means that bacteria can evolve rapidly.

Answer 23

Example
An example of an antibiotic resistance bacteria is MRSA.

Question 24

Reducing new resistant strains

Answer 24

Measures must be taken to reduce the emergence of new antibiotic resistance strains: Doctors should avoid prescribing antibiotics unnecessarily, for example for treating non-serious or viral infections. Patients must finish a course of antibiotics to make sure that all of the bacteria are killed. The use of antibiotics in agriculture (for example, cattle feed), should be restricted.

Question 25

Resistant strain of bacteria

Answer 25

If a mutated bacterial pathogen is resistant to antibiotics, when a person is treated with antibiotics, the bacteria will survive and go on to reproduce. This bacteria is the original ancestor of a new resistant strain. This bacteria will spread, as there will be no treatment for it, and people are not immune to it (as they were previously treated with antibiotics).

Question 26

Antibiotics

Answer 26

The development of new antibiotics is a slow and costly process. It struggles to keep up with the emergence of new strains.

Question 27

Bacteria reproduce and evolve

Answer 27

Rapidly

Question 28

To reduce the risks of

Answer 28

bacterial resistance, doctors should avoid prescribing antibiotics unnecessarily, patients must finish a course of antibiotics, and the use of antibiotics in agriculture should be restricted.

Question 29

Pentadactyl Limbs

Answer 29

By comparing similar structures in similar animals, we may be able to prove that these organisms have evolved from the same organism. An example of this is the pentadactyl limb (which means five digits or fingers). Many vertebrates (animals with backbones) have a very similar bone structure, even though their limbs looking very different from the outside. This is because organisms have evolved to different lifestyles in different places.

Question 30

How can looking at similar structures between organisms be used to provide evidence for evolution?

Answer 30

By comparing similar structures in similar animals, we may be able to prove that these organisms have evolved from the same organism. An example of this is the pentadactyl limb (which means five digits or fingers). Another example is that many vertebrates have a very similar bone structure, even though their limbs looking very different from the outside.

Question 31

Which animals have pentadactyl limbs?

Answer 31

Looking at the skeletons of animals shows that most vertebrates (animals with backbones) have pentadactyl limbs. The hooves of horses, flippers of whales, wings of birds and the feet of frogs and lizards all have five digits.

Question 32

Fossils

Answer 32

Fossils are the remains or traces of ancient life. Fossils are found in rocks and have been preserved by natural processes.

Question 33

Mineral replacement

Answer 33

Hard parts of organisms are gradually replaced by minerals as they decay slowly, creating a rock-like substance. When the surrounding sediment turns to rock, the teeth-shaped mineral structure remains distinct (different).

Question 34

Preservation when decay is not possible.

Answer 34

Where decomposers cannot act, preservation is possible. Decomposers cannot operate in glaciers (extreme, low temperatures) and peat bogs (extreme acidity).

Question 35

Hardening soft materials

Answer 35

The hardening of soft materials can produce casts or impressions, such as footprints. For example, clay hardens around an organism that is buried within it. This organism then decays, leaving behind a cast of itself.

Question 36

Fossils are the remains or traces of

Answer 36

ancient life, which are found in rocks and have been preserved by natural processes.

Question 37

Human Evolution

Answer 37

Fossils can be dated, so scientists have evidence for what organisms looked like at different periods in time. Comparing the fossils indicates how humans have changed over time.

Question 38

Ardi

Answer 38

The oldest fossilised human remains are of Ardi (from the species Ardipithicus ramidus) dating back 4.4 million years ago.

Question 39

Lucy

Answer 39

Another fossil was found called Lucy (from the species Australopithecus afarensis), which has been dated at 3.2 million years old.

Question 40

Leakey

Answer 40

There have been more recent discoveries by of human fossils by an archaeologist (fossil-hunter) called Leakey, who discovered fossils from 1.6 million years ago.

Question 41

Stone Tools

Answer 41

Stone tools show how humans have evolved: the more complex the tools used, the more developed the brain of the user. This can be linked with the fossil record.

Question 42

Basic tools

Answer 42

Very basic tools have been found dating back to 2.6 million years ago, but these were mainly flakes of rock with a sharp edge.

Question 43

Complex tools

Answer 43

At around 1.6 million years ago tools became more sophisticated and abundant.

Question 44

Dating tools

Answer 44

Carbon dating a stone tool does not tell us how old the tool is, it only tells us when the rock was originally formed. To determine when the stone tool was in use: Determine how deeply the artefact was buried. The deeper the object was stored, the older the object. Use known dates of other items or fossils found at that level. Compare the design to other stone tools that are already dated.

Question 45

Classification Systems Classification groups organisms by comparing their similarities and differences:

Answer 45

3-domain system Carl Woese proposed the 3 domain system. This classifies organisms based on chemical analysis. The 3 domains are: Archaea - primitive bacteria. Bacteria - true bacteria. Eukaryota - organisms possessing complex sub-cellular structures (protists, fungi, plants & animals).

Question 46

Traditional (Linnaean) classification system

Answer 46

The traditional classification system, devised by Carl Linnaeus, categorises organisms based on their structure and characteristics. He created 7 different groups - Kingdom, Phylum, Class, Order, Family, Genus, Species.

Question 47

Traditional (Linnaean) Classification System

Answer 47

The traditional classification system, devised by Carl Linnaeus, categorises organisms based on their structure and characteristics. Linnaeus classified biodiversity into seven different groups. The diagram shows the groups in descending order of size.

Question 48

To remember the order of the Linnaean classification (in descending size order): King Prawn Curry Or Fried Greasy Sausage.

Answer 48

Which species are being named? Tiger: Panthera tigris Lion: Panthera leo Human: Homo sapiens

Question 49

The Three-Domain System

Answer 49

The ‘three-domain system’ was proposed by Carl Woese and classifies organisms based on chemical analysis.

Question 50

Archaea

Answer 50

Primitive bacteria, many of which are extremophiles (i.e. live in extreme environments).

Question 51

Bacteria

Answer 51

True bacteria

Question 52

Eukaryota

Answer 52

Organisms that possess complex subcellular structures (e.g. protists, fungi, plants and animals).