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Alevel Biology > 4.3 > Flashcards

4.3 Flashcards

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1
Q

Why is it a huge task to place all living things into categories

A

Estimated 2million species alive today and each species must be studied in detail before it can be correctly placed in a group of similar organisms

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2
Q

Why do we categories species (3)

A

For our convenience, to make study of living things more manageable, to make identify organisms easier, to help use see relations between species

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3
Q

What does the currant system of classification use

A

8 taxonomic levels

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4
Q

What are the 8 taxonomic levels

A

Domain, kingdom, phylum, class, order, family, genus, species

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5
Q

Why came up with the 8 taxonomic levels

A

Linnaeus came up with 7 of them but Woesse added domain in at a later date

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6
Q

What is in domain

A

Highest taxonomic rank consisting of archea, eubacteria and eukaryotae

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7
Q

What is in kingdom

A

5 main kingdoms- plantae, fungi, animalia, protoctista (all eukaryotes), prokaryotae (all single celled organisms w no nucleus)

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8
Q

What goes into phylum

A

Major subdivision of the kingdom containing all groups of organisms that have same body plan such as possession of a backbone

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9
Q

What is in class

A

Group of organisms that all posses same general traits such as same number of legs

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10
Q

What is in order

A

Subdivision of class using additional info about organism like if it’s carnivore (Carnivora) or vegetable eating (herbivora)

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11
Q

What goes in family

A

A group of closely related genera like within order Carnivora we may recognise dog family and cat family

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12
Q

What is in genus

A

A group of closely related species

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13
Q

What is in species

A

Basic unit of classification, all members of a species show some variation but essentially are the same

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14
Q

How do you remember the taxonomic groups

A

Domain King Prawn Curry Or Fat Greasy Sausages

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15
Q

Is it easier or harder to class species at the top of the taxonomic levels and what does this mean

A

Difference between organism can be very great at the top so it is easier to place organisms into domain, kingdom, phylum

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16
Q

Where does it become more difficult to class organisms

A

Within the class as the difference between classes in one phylum may not be very great

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17
Q

Is it easier or harder to class organisms as you go further down and what does this mean

A

Harder to separate closely related species and to place a species accurately so more detail and descriptions needed

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18
Q

What does binomial name mean

A

2 names

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19
Q

How does binomial name work

A

The organisms genus name followed by their species name

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20
Q

How should you write a binomial name

A

Either in italics or underlined and the species should not have a capital letter

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21
Q

Who were species classified before Linnaeus divided his system

A

Species identified by a column name or a long detailed description

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22
Q

Why does using a column name, system before Linnaeus, not work well

A

Some organisms may have different column names in different parts of a country, different common names used in different countries, translation of language may give different name, same common name may be used for different species in different parts of the world

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23
Q

Why did Linnaeus use Latin

A

As it’s universal, meaning whenever a species is named it has a universal name which every scientist will use in every country to avoid potential confusion of column names

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24
Q

What is biological definition of a species

A

A group of organisms that can freely interbreed to produce fertile offspring

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25
Q

Why doesn’t the biological definition of species work for all organisms

A

Doesn’t work for organisms that reproduce asexually and hard to apply to organisms only known as fossils

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26
Q

What is the phylogenic definition of species

A

A group of individuals that are very similar in appearance, anatomy, physiology, biochemistry and genetics

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27
Q

What does being so similar mean in terms of species habitat

A

Many species occupy same ecosystem

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28
Q

Why was the facts that species often share same ecosystem useful before Linnaeus

A

Fact was used in early classification which were only based on appearance and anatomy, for many species species this provided enough info to allow accurate classification but mistakes were easily made

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29
Q

In earliest attempt by Aristotle to classify all living things what did he do

A

He classified all living things into plants or animals and subdivided animals into: live and move in water, live and move on land, live in air

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30
Q

What did Aristotle for earliest attempt of classification base his classings on

A

He based it on similarities he saw- some animals had wings, some had fins, some had legs

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31
Q

What was the issue with Aristotle’s classification system (3)

A

His way of classifying mean fish and turtles were classified together, birds and insects together and mammals with frogs

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32
Q

Since Aristotle’s classification attempt what has happened

A

It’s been adapted and made more accurate as more research is done and more info becomes available

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33
Q

Early classification like Linnaeus were based on observable feature, how has this changed to modern day and why

A

By 17th century scientists had microscopes, they were no longer limited to those features of organisms that you can see

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34
Q

For many years what was the accepted number of kingdoms and what is it now

A

Was 2 (plantae and animalia) now 5 (fungi, protocista, prokaryotae)

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35
Q

Why were 3 more kingdoms later added

A

As more organisms found and studied in detail it become clear they couldn’t fit into either category

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36
Q

In early 2 kingdoms classification how did they classify single celled organisms

A

Animal kingdom included single celled organisms with some animal like features and plants kingdom had single-celled organisms with plant-like features

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37
Q

What did electron microscope reveal about single celled organisms with animal or plant features

A

Revealed more detail and made clear some single celled organisms had plant and animal features

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38
Q

What is an example of a single celled organism with plant and animal features

A

Eugena is single celled organisms with chloroplast to photosynthesise but has flagella to move around so doesn’t clearly fit into plant or animal

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39
Q

Why doesn’t fungi fit into plant or animal kingdom

A

They don’t move-similar to plants, and their hyphae grows into surrounding tissue like roots but they don’t photosynthesise-they digest organic matter and absorb nutrients- similar to animals

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40
Q

What kingdom was fungi in, in the 2 kingdom classification

A

Plantae

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41
Q

Due to upheaval in world of taxonomic, what happened

A

Led to the adoption of 5 kingdom classification based on observable features as well as their anatomy at a microscopic level

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42
Q

What are features of organisms in the kingdom prokaryotae

A

Have no nucleus, have looped and naked DNA, no membrane bound organelles, have smaller ribosomes than eukaryotes, have smaller cells than eukaryotes, may be free living or parasitic (disease causing)

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43
Q

What are features of organisms in the kingdom protoctista

A

They are eukaryotes, mostly single celled, wide variety of forms but they don’t fit into any other kingdom, show various plant or animal features, mostly leaving free, have autotrophic or heterotrophic nutrition

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44
Q

What is meant by heterotrophic and autotrophic

A

Autotrophic- make their own food like plants photosynthesise heterotrophic- need to find food to ingest like ingesting prey or feeding on extracellular enzymes

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45
Q

What are features of organisms in kingdom fungi

A

Are eukaryotes, can exist as single cells or they have mycelium consisting of hyphae, have cell wall made of chitin, they have multinucleate cytoplasm, mostly free living and saprophytic

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46
Q

What is definition of saprophytic

A

Can cause decay of organic matter

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47
Q

What are features of organisms in kingdom plantae

A

Are eukaryotes, are multicellular, cells surrounded by cellulose cell wall, are autotrophic, contain chlorophyll

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48
Q

What are features of organisms in kingdom animalia

A

Are eukaryotes, are multicellular, are heterotrophic, usually can move around

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49
Q

What is the 3 domain classification

A

By Woese, he examined cells ribosomal RNA and classified them into eubacteria, archaea and eukaryotae

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50
Q

What is classification

A

The process of sorting things into groups, we may sort things out for our simple convenience or the classification may be based on many important similarities and differences between the groups

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51
Q

What is artificial classification and example

A

Based on only a few characteristics and doesn’t reflect any evolutionary relationships, so provides limited info (eg. A wildflower guide often has all plants with yellow flowers on one page and pink on another to make it easier for user to identify the correct flower

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52
Q

What is natural classification

A

Biological classification involves detailed study of individuals in a species (individuals show variation) such as species dog has pug, retriever, cockapoo, underneath visible differences dogs are very closely related, 2 species can also be closely related, closely related genera will be placed together in same family creating an organised hierarchy of organisms

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53
Q

What does natural classification use to order organisms into a hierarchy

A

Uses many characteristics, it reflects evolutionary relationships, provides lots of useful information and may change with advancing information

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54
Q

Where could a natural classification that reflects real relationships between groups be useful

A

If you wanted to find out about rate and endangered species, we may not want to risk harming the few remaining members of the species but we can find other closely related species that are not endangered and carry out research on this species instead to provide information which may help the conservation of the endangered specie

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55
Q

What does modern classification reflect

A

Evolutionary history of the living world

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56
Q

What does the statement ‘we can think of all organisms as belonging to an evolutionary tree’ mean

A

Any 2 species living today have common ancestors at some past time and the time 2 species started evolving separately is a branch on the tree, more recent the common ancestor the more closely related the 2 species are

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57
Q

What is phylogeny

A

Study of evolutionary relationships between species, it involves studying how closely different species are related

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58
Q

What can we see using an evolutionary/phylogenic tree

A

We can see certain evolutionary relationships that indicate how closely related the species are

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59
Q

Are common ancestors alive today

A

Common ancestors of lots of organisms are no longer alive today, by reading an evolutionary tree you can see which are and which are extinct

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60
Q

Although using observable features to classify has been largely successful what is is a problem with it

A

Convert evolution- organisms living in the same environment so adapt in similar ways, so they may look similar but they are actually unrelated

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61
Q

What has the most recent research on classification provided

A

It’s used a wider range of techniques and produced more detailed evidence for classification

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62
Q

What is a modern way of determining how closely related a species is to another and how

A

Using biological molecules, certain large biological molecules are in all living things but may not be identical in every species, these molecules involved in most fundamental life processes like respiration and photosynthesis, so if we assume earliest living things had identical versions of molecule then differences Is down to evolution

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63
Q

By looking at biological molecules how do you tell if a species is closely related to another

A

2 organisms with similar molecules will be closely related as they haven’t separately evolved for long, 2 organisms with very different versions of molecules are less closely related as separately evolved for longer, difference between these molecules in different species reflect evolutionary relationships

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64
Q

What is the point of using biological molecules when we already have a classification system

A

Although the evidence largely backs up evolutionary relations that have already been worked out, it clarifies and corrects relationships that we were unsure about

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65
Q

What is cytochrome c

A

A protein used in process of respiration, all living things that respire have cytochrome C

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66
Q

It cytochrome C identical in all species

A

No, proteins are large chains made from a chain of smaller units, amino acids, amino acids in cytochrome c can be identified and if we compared amino acid sequence between 2 species we can draw certain conclusions

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67
Q

What conclusions can be drawn by analysing cytochrome c amino acid sequence in 2 different species

A

If sequence is same species must be closely related, if sequence is different species not closely related, more differences found between 2 sequences less closely related they are

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68
Q

Give an example of analysis of cytochrome c

A

Amino acid sequence of cytochrome c in humans and chimpanzees are identical, only 1 difference between humans and rhesus monkey but 11 differences between dogfish and humans

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69
Q

What is DNA

A

Another biological molecule found in all living things which provides genetic code and instructions for producing proteins

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70
Q

What does it mean for comparing 2 species that DNA code is same for all organisms

A

Means particular sequence if DNA codes for same sequence of amino acids in bacterium as in any other organism

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71
Q

What is changes to sequence of bases in DNA called

A

A mutation

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72
Q

When do mutations occur

A

At random

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73
Q

Comparisons of DNA is another way to classify species, how?

A

More similar sequence in a part of DNA the more closely related to species are, if there are many differences the species have evolved separately for a long time and so less closely related

74
Q

Is comparing DNA an accurate way of classifying species

A

Yes, probably the most accurate way to determine how related species are

75
Q

When did woese suggest a new classification system

A

1990

76
Q

What did Woese base the 3 domain classification on

A

His ideas on detailed study of ribosomal RNA gene

77
Q

What did Woese devise as how to classify species

A

He divided kingdom prokaryotae into 2 groups- eubacteria and archaea and then there was eukaryotae

78
Q

Why did Woese decide to divide kingdom prokaryotae into eubacteria and archaea

A

Bacteria are fundamentally different from archaea and eukaryotae

79
Q

What are some structural difference of eubacteria from eukaryotes and archaea

A

Bacteria have different cell membrane structure, flagella with different internal structures, different enzymes for synthesising RNA, naked DNA, different mechanisms for DNA replication and synthesising RNA

80
Q

What similar features to archaea and eukaryotae share

A

Similar enzymes for synthesising RNA, similar mechanism for DNA replication and synthesising RNA, production of histone proteins that bind to their DNA

81
Q

What basic mechanisms are RNA AND DNA a part of

A

A basic mechanisms that translates genes into visible characteristics

82
Q

Why did Woese argue differences between eubacteria and archaea are fundamental

A

He suggested 2 groups are more different from each other than archaea and eukaryotae and an accurate classification system must reflect this difference

83
Q

Is Woeses 3 domain system accepted or not

A

Yes it is now widely accepted by most biologists

84
Q

Who was Darwin

A

A naturalist who spent much of his life observing and studying living organisms

85
Q

Was the theory of evolution Darwin’s idea

A

No, the idea that 1 species may evolve from another over time wasn’t a new idea but Darwin proposed a mechanism for this process making theory of evolution easier to believe, the proposed mechanisms was natural selection

86
Q

Why did the theory of evolution cause upheaval in Victorian Britain

A

As it countered religious beliefs of the time

87
Q

When did Darwin’s ideas of natural selection first begin

A

During a 5year trip round world in HMS Beagle, during his trip he visited Galápagos Islands where he found many unusual species, many were similar to ones on South America’s mainland but what interested Darwin was the clear variation between members of same species found on different islands

88
Q

What species did Darwin’s notice which helped him devise his theory of natural selection and what did he conclude

A

What appeared to be a wide variety of birds were all in fact closely related finches, Darwin concluded that 1 species had arrived in island from mainland and then evolved into many different species

89
Q

Who was Wallace

A

Another naturalist who independently came to same conclusion as Darwin, Wallace made collections in Amazon and south east Asia

90
Q

Did Wallace and Darwin every work together

A

Yes, their first publication were joint papers on the subject of evolution by natural selection - soon followed by Darwin’s book ‘The origins of species’

91
Q

What 4 observations did Darwin make to do with natural selection

A

1.offspring generally appear similar to their parents 2.no 2 individuals are identical 3.organisms have ability to produce large numbers of offspring 4.populations in nature tend to remain a fairly stable size

92
Q

How did Darwin realise variation was key to understanding how species change

A

He saw when too many young produced their is a competition for food and resources. As all offspring are different some may be better adapted than others, better adapted individuals pass their characteristics to next generation so the population changes/evolves to become better suited to its environment

93
Q

How can Darwin’s conclusions about survival of the fittest be summarised

A

There’s a struggle to survive, better adapted individuals survive and pass on their characteristics and over time a number of changes may give rise to new species

94
Q

What interesting facts do fossils show (3)

A
  1. In past, the world was inhabited by species different from today 2.old species died out and new have arisen 3.new species that have appear are often similar to older one found in the same place
95
Q

How did Darwin’s fascination between similarities from fossils and species alive today help him understand natural selection

A

He began to understand fossil species gave rise to modern species, he felt this was as more modern species had variations meaning they were better adapted to their environment

96
Q

What other differences was Darwin surprised about between old fossils and today’s species

A

Many fossil species were much larger than species today but otherwise appear similar such as modern armadillo grow only to 15cm but glyptodont was many times this size but looked the same

97
Q

What is 1 of the most complete fossil records

A

The horse, evolution of modern horses can be followed through a sequence of species all very similar to each other, their similarities and sequence in time provide evidence that one species arose from previous one

98
Q

What do recent studies of biological molecules provide

A

Very strong evidence for evolution

99
Q

How does biological molecule studies provide strong evidence for evolution

A

Fact that certain molecules are found throughout living world is evidence itself, if one species gives rise to another, both are likely to have same biological molecules which suggests that all species arose from one original ancestor

100
Q

What biological molecules are good evidence of change/evolutions

A

Cytochrome c, DNA

101
Q

How can genes between species be compared

A

By sequencing the bases in the DNA, greater number of similarities between gene sequences means more closely related a species is and more recent their evolution was, also shows more distantly related species have more differences in their DNA

102
Q

What does comparison of human DNA with chimpanzees, gorillas and baboons show in terms of their evolutionary relationship

A

1.2% of our coding differs form chimpanzees, 1.6% different in gorilla and 6.6% different between humans and baboons

103
Q

What is variation

A

Presence of differences between individuals

104
Q

Do do individuals ever look exactly the same

A

No not even if the look really similar

105
Q

Are identical twins identical

A

Identical twins start as 1 cell cells that divides and separated into two cells and each cell develops into a separate person, so while 2 original cells had some genetic information, replication of DNA and meiosis causes crossing over which changes DNA in 2 individuals and slight environment differences in womb or after birth can mean 2 individuals show physical differences

106
Q

Do humans show variation

A

Yes like any species, any characteristics you find will vary in a population

107
Q

What are some characteristics that vary in a population

A

Eye colour, hair colour, skin colour, nose shape all characteristics that show variation between people

108
Q

What is intraspective variation

A

Characteristics that show variation within a species, greater the genetic diversity of species the greater their intraspecific variation

109
Q

Is variation between species obvious

A

Yes as it is used to classify different species

110
Q

What is continuous variation

A

Where there are 2 extremes and a full range of intermediate values between those extremes

111
Q

In continuous variation where do people usually lie on a graph

A

Close to the mean values, number of people at extremes is low creating a bell shaped curve

112
Q

How is continuous variation often regulated

A

By more than 1 gene and can be influenced by environmental factors too

113
Q

What are examples of continuous variation

A

Height in humans, length of leaves on oak tree, length of stalk on road stall, number of flagella on bacterium

114
Q

How would you usually plot continuous variation

A

It is usually quantifiable so best to use a histogram to plot

115
Q

What is discontinuous variation

A

Where there are 2 or more distinct categories with no intermediate values

116
Q

How evenly distributed is discontinuous variation

A

Members of a species may be evenly distributed between the different forms or there may be more than one than the other

117
Q

What factors affect discontinuous variation

A

Usually regulated by a single gene and not influenced by the environment

118
Q

What are examples of discontinuous variation

A

Gender (male/female/hermaphrodite), some bacteria have flagella/some don’t, human blood groups (A, B, AB, O)

119
Q

How is discontinuous variation shown on a graph

A

Shown on a bar chart

120
Q

What are the 2 causes of variation

A

Genetic and environmental factors

121
Q

What is genetic variation

A

Genes we inherit from our parents provide information that’s used to define our characteristics, combination of alleles that we inherit isn’t the same as any living thing (except identical twins), we may share many alleles with other members of our species and share genes with other species but never a complete match

122
Q

How many genes in each human cells and what does this mean in terms of variation

A

Approximately 20,000 genes in each human cell and many of these have more than 1 allele so the chance of 2 individuals having same exact combination of alleles is remote, so combination of characteristics that each of us posses is unique

123
Q

Why is environmental variation

A

Many characteristics affected by the environment we live in

124
Q

What is examples of environmental variation (3)

A

Overfed pet will become obese or a persons skin will become darker in exposure to sunlight, hawthorn tree often grows to 6m but if nibbled by animals or cut by farmers it becomes busy, it hawthorn grows in rock crevice with little soil and water may only grow 150cm (environment affects growth rate)

125
Q

Are genetic and environmental variation factors isolated from each other

A

No, many characteristics affected by both causes of variation

126
Q

Give an example of genetic and environmental factors in variation working together

A

In past century humans have become taller due to better diet but even if u have an excellent diet it’s unlikely u will be tall if the rest of your family is short as you are limited by genes

127
Q

Are all are genes always active, give example

A

No, like when reaching puberty many changes occur as different genes become active

128
Q

Can environmental factors alter gene activity

A

Changes in environment can directly effect which genes are active

129
Q

Why do we use statistical tests in variation

A

Data about variation may provide a series of numbers but we don’t know what they mean, the small difference between 2 figures may or may not be significant but using correct statistical tests can help to determine if difference observed is significant or simply natural variation

130
Q

What is standard deviation

A

Measure of variation, measures amount of variation or spread from the mean

131
Q

What does low standard deviation indicate

A

Indicates data has a narrow rand and points closely grouped to mean indicate reliability

132
Q

What does high standard deviation mean

A

Indicates data points have a larger range and less well grouped, indicates lower reliabilty

133
Q

What does the s, x, x with line on top and n stand for in standard deviation equation

A

S=standard deviation x=individual value x w line=mean value n=number of data points

134
Q

What do we say once we have calculated standard deviation

A

We can say that the spread of our data set is the mean +_ the standard deviation

135
Q

What is t-test used for

A

To compare 2 means, test of difference between 2 means is a significant difference

136
Q

What is the first step in a t-test

A

We state a null hypothesis that there is no significant difference between the mean of the 2 data sets and the t-test tests if we reject or accept hypothesis

137
Q

What does x1 w line, S^21, n1, x2 w line, S^22, n2 mean in t-test equation

A

X1 w line=mean of first data set S^21=standard deviation of 1st set squared n1=number of data points in first set x2 w line, S^22, n2 refer to second set of data

138
Q

What is degrees freedom defined as

A

Number of values in a statistical calculation that are free to vary usually calculated as (sample size)-(number of data sets)

139
Q

What is degree of freedom for t-tests

A

2 data sets so (n1+n2)-2=18

140
Q

How do you work out if calculated t value is significant or not

A

Take into account number of degrees of freedom, we can use a table of t values to asses if calculated value indicates significant difference, in biology 5% is a significant difference, if calculated value greater than 5% we can consider difference to be significant between 2 sets of data, if calculated value below 5% we can consider difference insignificant

141
Q

What is correlation coefficient used for

A

To consider relationships between 2 sets of data, spearman rank correlation tells us if 2 sets of data are correlated or not

142
Q

What is an adaptation

A

Any variation that helps an organism survive

143
Q

Why do organisms adapt to their environment

A

Adaptations help organisms cope with environmental stresses and obtain things they need to survive

144
Q

What can a well adapted organism do

A

Find enough food/photosynthesise well, find enough water, gain enough nutrients, defend itself from predators and diseases, survive physical conditions of its environment (like changes in temp, light and water availablity), respond to changes in its environment, have sufficient energy to allow successful reproduction

145
Q

What are the 3 ways adaptations can work

A

Anatomical, behavioural or physiological

146
Q

What is marram grass

A

A specialised plant adapted to living on sand dunes where little water is available, so marram grass must be adapted to take up as much water as possible and avoid losing it- its a xerophyte

147
Q

What are anatomical adaptations

A

Means structural adaptations, any structure that enhances survival of an organism is an adaptation

148
Q

What are some anatomical adaptations of marram grass and how (7)

A

Long roots-enables pants to reach water deep underground, widespread roots- it can absorb lots of water when becomes available and helps stabilise sand dune, curled leaves- reduces SA exposed to wind and traps air inside against lower epidermis so moisture can build, hairs on lower epidermis-reduce air movement so water retained, stomata in pits in folded lower epidermis-water vapour builds in pits reducing loss of water vapour, low density of stomata-fewer stomata so less water loss, thick waxy cuticle-reduces evaporation of water form leaves

149
Q

What are behavioural adaptations

A

Aspect of behaviour of an organism that helps it to survive in conditions it lives in

150
Q

What is an example of a behavioural adaptation

A

When you touch an earthworm and it contacts and withdraws into its burrow, earthworm has no eyes so it can’t tell you aren’t a bird about to eat it, it’s rapid withdrawal is a behavioural adaptation to avoid being eaten

151
Q

Do plants show behaviour adaptations (3)

A

Yes, marram grass responds to shortage of water by rolling leaf more tightly and closing stomata, both changes help to reduce transpiration and when covered by sand, marram grass grows quicker to reach sunlight

152
Q

What are physiological/biochemical adaptations

A

Ensures correct functioning of cell processes

153
Q

What is an example of a physiological/biochemical adaptation

A

Yeast saccharomyces can respire sugars aerobically or anatomically depending on oxygen availability

154
Q

What physiological/biochemical adaptations do marram grass show (hinge cells and guard cells)

A

Ability to roll leaves is due to action of specialised hinge cells in lower epidermis, these cells lose water when water is scarce and lose their turgidity which rolls leaf tighter, when water available hinge cells become turgid opening up leaf to allow easier access to CO2 for photosynthesis, guard cells work in similar way-open when turgid and close when flaccid

155
Q

What physiological/biochemical adaptations do marram grass show (salt tolerance)

A

Marram isn’t very salt tolerant but maintains a cell water potential that’s lower than other plants to enable it to survive salty conditions found by sea

156
Q

What physiological/biochemical adaptations do marram grass show (lignified cells)

A

Marram leaves contain many lignified cells that provide support when turgidity lost which keeps leaf upright when water not available

157
Q

As adaptations selected by the environment what sometimes happens

A

2 unrelated species living in similar habitats may evolve with similar adaptations, where those species adopt a similar lifestyle they evolve to look similar (analogous features)

158
Q

What is an example of convergent evolution

A

Placental Mole is a burrowing mammal that feeds on small animals in soil, marsupial moles live in Australia and part of a group of mammals that have been evolving separately from placental moles from 100million years, despite this separation they share a number of characteristics and look similar (eg.cylindrical body, small eyes, strong front legs, large claws on front legs, short fur and tail, rough nose for protection)

159
Q

What is convergent evolution

A

When 2 unrelated organisms adapt with similar traits as they live in the same environment

160
Q

What is natural selection

A

An individual that has characteristics which help it survive in its environment is more likely to live long enough to reproduce

161
Q

How does the process of evolution work

A

By selecting individuals with particular adaptations to survive and reproduce so that these adaptations passed from generation to generation over a longs period of time and more and more individuals in a population will have that adaptive characteristic, an adaptation has been selected

162
Q

What are the first 3 steps of how natural selection works

A

1.mutation creates alternative version of a gene (allele), 2.creates genetic variation between individuals of a species (infraspecific variation), 3.once variety exists environment can ‘select’ (when resources scarce environment will select those variations that give an advantage, there is selective pressure)

163
Q

What are the last 3 steps of how natural selection works

A

4.individuals with advantageous characteristics will survive and reproduce, 5.so they pass on their advantageous characteristics (inheritance), 6.next generation will have more individuals with successful characteristics and over time groups of organisms become well adapted to its environment (adaption)

164
Q

What occurs first variation or evolution, how do we know this

A

Variation occurs before evolution can take place, its genetic variation that’s important for evolution, variation due to environmental factors won’t be passed to offspring

165
Q

Does evolution still occur today

A

Evolution still happens today, when species placed under new selection pressure, different characteristics will be selected, evolution will occur, this is most obvious in organisms with a short life cycle

166
Q

Why are some insects described as pests

A

They eat out food crops/cause damage to them, they can also act as vectors which transmit pathogens

167
Q

What have humans tried to do to stop pests, has it been successful

A

Humans devised ever more ingenious ways to kill insects but some always survive

168
Q

What are pesticides and what are insecticides

A

Chemicals designed to kill pests, insecticides specifically kill insects which applies very strong selection pressure

169
Q

How does insecticides work and how don’t they

A

If an individual is susceptible then it will die, if it has some form of resistance it may survive which will allow individuals with some resistance to reproduce and pass on resistant characteristics so resistance quickly spreads through whole population

170
Q

When was resistance to pesticides first documented

A

1914, when scale insects found to be resistant to inorganic insecticides

171
Q

What has humans developing many different types of insecticides created

A

Many cases of insects becoming resistant to many types of insecticides as resistance can arise in as little as 2years

172
Q

What is a big problem with insects becoming resistant to pesticides

A

Pesticide can accumulate in food chain, if insects are resistant to pesticides they survive application of these chemicals, the insect may be eaten by predators causing predators to receive large dose of insecticide so insecticide moves up the food chain

173
Q

How can humans receive a large does of insecticide

A

Due to increasing resistance and fact DDT accumulates in food chain, it had been banned in many areas but DDT is still used in household spraying programmes in certain countries

174
Q

What is a powerful selection pressure on bacteria

A

Use of antibiotics

175
Q

What happens when taking antibiotics

A

Most of bacteria is killed but may be 1 or 2 resistant bacteria to antibiotics (they are rarely unaffected by antibiotics but still have more resistance than most bacteria)

176
Q

What happens once most of the bacteria in our body has been killed by antibiotics and what does this often mean

A

Once majority of bacteria killed you feel better so many people stop taking antibiotics before prescribed course which allows resistant bacteria to survive and reproduce to create resistant strains of bacteria

177
Q

What does overuse/ incorrect use of antibiotics cause

A

Leads to strains of bacteria resistant to almost all antibiotics

178
Q

What do some doctors now do to reduce chance of resistant bacteria

A

Prescribe multiple antibiotics which reduces chance bacteria will survive

179
Q

What is an example of a bacteria that has gained a wide range of resistance

A

The superbug MRSA

180
Q

What is MRSA

A

A bacteria that has gained ever increasing resistance to an every increasing range of stronger drugs

181
Q

What is an example of the evolutionary arms race

A

Medical researchers struggling to develop new and effective drugs as bacterial populations rapidly become resistant to them

182
Q

What happens during the selection process of insects and insecticide

A

Before selection baring ranges of resistance, variation caused by mutations that creates great genetic variation within a species, directly after selection least resistant individuals have been killed and only resistant individuals remain, after population of partly resistant individuals reproduce so next generation has more resistant individuals

Alevel Biology (25 decks)

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