topic 5

Question 1

when does evolution occur?

Answer 1

when heritable characteristics of a species change

Question 2

what is the mechanism of evolution?

Answer 2

natural selection

Question 3

fossil record

Answer 3

• many sequences of fossils are known, which link together existing organisms with their likely ancestors
• sequence in which fossils appear matches the sequence in which they would be expected to evolve, with bacteria/simple algae appearing first, then fungi and worms, and then land vertebrates
• sequence fits with the ecology of the groups, with plant fossils appearing before animal, plants on land before animals on land, and plants suitable for insect pollination before insect pollinators

Question 4

selective breeding of domesticated animals

Answer 4

• by breeding members of a species with a desired trait, the frequency of this trait becomes more common in successive generations
• targeted breeds can show significant variation in a (relatively) short period
• this shows that selection can cause evolution

Question 5

homologous structures

Answer 5

Comparative anatomy of groups of organisms may show certain structural features that are similar, implying common ancestry

the evolution of homologous structures by adaptive radiation explains similarities in structure when there are differences in function

Question 6

define adaptive radiation

Answer 6

when several new species rapidly diversify from an ancestral source, with each new species adapted to utilise a specific unoccupied niche

Question 7

define homologous structures

Answer 7

Anatomical features that are similar in basic structure despite being used in different ways

Question 8

speciation

Answer 8

• speciation is the evolutionary process by which two related populations gradually diverge into separate species that can no longer interbreed and produce fertile offspring
• the degree of genetic divergence between geographically separated populations will gradually increase the longer they are separated

Question 9

give 5 pieces of evidence for evolution

Answer 9

• fossil record
• selective breeding of domesticated animals
• homologous structures
• speciation
• patterns of variation

Question 10

patterns of variation

Answer 10

• continuous variation across the geographical range of related populations matches the concept of gradual divergence
• Darwin gave examples of populations that are recognisably different, but not the the extent that they are clearly separate species
• this disproves the idea that species were created as distinct types (and should be constant across their geographic range) or that they are unchanging

Question 11

give an example of a homologous structure and explain its significance

Answer 11

the pentadactyl limb in a variety of different animals: mammals, birds, amphibians and reptiles all share a similar arrangement of bones in their appendages based on a five-digit limb

however, they may also be highly dissimilar according to the mode of locomotion:
eg Human hands are adapted for tool manipulation (power vs precision grip),
Bird and bat wings are adapted for flying, whale and dolphin fins are adapted for swimming

Question 12

describe the development of melanistic insects in polluted areas

Answer 12

Peppered moths (Biston betularia) exist in two distinct forms – a light colouration and a darker melanic variant

• adult Biston betularia moths fly at night to try to find a mate and reproduce.
• during the day they roost on the branches of trees.
• birds and other animals that hunt in daylight predate moths if they find them.
• in unpolluted areas tree branches are covered in pale-coloured lichens and peppered moths are well camouflaged against them.
• sulphur dioxide pollution kills lichens. Soot from coal burning blackens tree branches.
• melanic moths are well camouflaged against dark tree branches in polluted areas.
• in polluted areas the melanic variety replaced the peppered variety over a relatively short time, but not in non-polluted areas

Question 13

natural selection can only occur if

Answer 13

there is variation amongst members of the same species - if all individuals in a population were identical, there would be no way of some being favoured over others

Question 14

give 3 sources of variation

Answer 14

1. mutation - new alleles produced by gene mutations enlarge the gene pool of a population
2. meiosis - produces new combinations of alleles by breaking up the existing combination in a diploid cell, through crossing over and the independent orientation of bivalents
3. sexual reproduction involves the fusion of male and female gametes, ensuring a new combination of alleles.

Question 15

define adaptations

Answer 15

characteristics that make an individual suited to its environment and way of life. these develop by natural selection over time.

Question 16

species tend to

Answer 16

produce more offspring than the environment can support, which may lead to a struggle for existence within a population due to competition for resources

Question 17

describe how natural selection leads to change within a species

Answer 17

1. individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring
2. individuals that reproduce pass on genetic characteristics to their offspring

natural selection thus increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within a species.

Question 18

give an example of adaptive radiation and natural selection

Answer 18

changes in beaks of finches on Daphne major

Different finch species demonstrated adaptive radiation and show marked variation in beak size and shape according to diet.

G. fortis’ diet consists of seeds, which when weather conditions are normal are plentiful, small, and soft, but which become fewer, larger, and tougher during times of drought
The Grants observed a wide range of beak sizes in G. fortis when weather conditions were normal, but found that during periods of drought beak size increased
This is because G. fortis were forced to feed on larger, harder seeds, which only the larger-beaked individuals were able to crack open, so most of the population died.

Question 19

give 4 reasons why antibiotic resistance has grown so quickly

Answer 19

• there has been very widespread use of antibiotics, both for treating diseases and in animal feeds used on farms.
• bacteria reproduce very rapidly, with a generation time of less than an hour.
• populations of bacteria are often huge, increasing the chance of a gene for antibiotic resistance being formed by mutation.
• bacteria can pass genes on to other bacteria in several ways, including using plasmids, which allow one species of bacteria to gain antibiotic resistance genes from another species.

Question 20

describe the process of development of antibiotic resistance

Answer 20

1. there is a population with no antibiotic-resistant bacteria
2. an antibiotic resistance gene is formed by mutation in one bacterium//received from a bacterium in another population
3. population with some antibiotic-resistant bacteria
4. when the antibiotic is used natural selection takes place

Question 21

what is the binomial system?

Answer 21

a system of scientific names for species that is universal among biologists and has been agreed and developed at a series of congresses. this is applied whenever species are discovered

Question 22

give 4 rules of the binomial system

Answer 22

1. the genus name begins with an upper-case (capital) letter and the species name with a lower-case (small) letter.
2. in typed or printed text, a binomial is shown in italics
3. after a binomial has been used once in a piece of text, it can be abbreviated to the initial letter of the genus name with the full species name
4. the earliest published name for a species is the correct one

Question 23

how do taxonomists classify species?

Answer 23

using a hierarchy of taxa

Question 24

state the 3 domains into which all organisms are classified

Answer 24

bacteria, archaea, eukaryota

Question 25

bacteria - histones associated with DNA - presence of introns - structure of cell walls - cell membrane

Answer 25

- absent - rare or absent - made of peptidoglycan - glycerol-ester lipids; unbranched side chains; d-form of glycerol

Question 26

archaea - histones associated with DNA - presence of introns - structure of cell walls - cell membrane

Answer 26

- proteins similar to histones bound to DNA - present in some genes - not made of peptidoglycan - glycerol-ether lipids; unbranched side chains; l-form of glycerol

Question 27

eukaryota - histones associated with DNA - presence of introns - structure of cell walls - cell membrane

Answer 27

- present - frequent - not made of peptidoglycan; not always present - glycerol-ester lipids; unbranched side chains; d-form of glycerol

Question 28

state the 7 taxa used to classify eukaryotes

Answer 28

kingdom phylum class order family genus species (katy Perry comes over for grape soda)

Question 29

going up the taxa hierarchy, the taxa include -------- numbers of species which share ------ features

Answer 29

larger; fewer

Question 30

in natural classification, the genus and accompanying higher taxa consist of

Answer 30

all the species that have evolved from one common ancestral species

Question 31

state and explain the two advantages of natural classification

Answer 31

1. Identification of species is easier; if a new organism is found and it is not obvious what species it is, this can be identified by first assigning it to a kingdom, then the phylum, and so on. 2. Because all of the members of a group in a natural classification have evolved from a common ancestral species, they inherit similar characteristics. This allows prediction of the characteristics of species within a group

Question 32

describe the process of reviewing classification

Answer 32

taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species

Question 33

what are dichotomous keys used for?

Answer 33

used to identify different organisms, based the organism's observable traits

Question 34

state the 4 main plant phyla

Answer 34

1. Bryophyta - mosses, liverworts, hornworts 2. filicinophyta - ferns 3. coniferophyta - conifers 4. angiospermophyta - flowering plants

Question 35

bryophyta

Answer 35

structures vascularisation reproduction other features

Question 36

filicinophyta

Answer 36

structures vascularisation reproduction other features

Question 37

coniferophyta

Answer 37

structures vascularisation reproduction other features

Question 38

angiospermophyta

Answer 38

structures vascularisation reproduction other features

Question 39

state the 7 main animal phyla

Answer 39

Porifera, cnidaria, Platyhelminthes, annelida, Mollusca and anthropda, chordata

Question 40

learn the characteristics of each animal phyla

Question 41

learn the features of each of the vertebrate classes

Answer 41

birds, mammals, amphibians, reptiles and fish (

Question 42

classify the grey wolf

Answer 42

K- animalia P- chordata C- mammalia O- carnivora F- carnidae G- canis S- lupus

Question 43

classify the date palm

Answer 43

K- plantae P- angiospermophyta C- monocotyledoneae O- palmales F- arecaceae G- phoenix S- dactylifera

Question 44

define a clade

Answer 44

a group of organisms that have evolved from a common ancestor

Question 45

how can we identify members of a clade?

Answer 45

from the base sequences of a gene or the corresponding amino acid sequence of a protein

Question 46

describe the concept of molecular clocks

Answer 46

sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor a greater number of differences between comparable base sequences suggests more time has past since two species diverged; hence, the more similar the base sequences of two species are, the more closely related the two species are expected to be

Question 47

traits can either be

Answer 47

analogous or homologous

Question 48

describe the difference between analogous and homologous traits

Answer 48

- homologous structures are similar because of similar ancestry (eg chicken wing/human arm/other pentadactyl forelimbs) - analogous structures are similar because of convergent evolution (show similarities in structure but evolved independently)

Question 49

why is morphology (form and structure) now rarely used for identifying members of a clade?

Answer 49

evidence from cladistics has shown that classifications of some groups based on structure did not correspond with the evolutionary origins of a group or species, leading to reclassification. problems in distinguishing homologous and analogous structures have led to classification mistakes in the past, so evidence from base/amino acid sequences is trusted more

Question 50

define cladograms

Answer 50

tree diagrams that show the most probable sequence of divergence in clades

Question 51

branching in a cladogram is assumed to match

Answer 51

the hypothetical ancestral species splitting to form two or more species

Question 52

describe cladograms including humans and other primates

Answer 52

check photo

Question 53

give the key features of a cladogram

Answer 53

check photo

Question 54

describe the issues with classification of the figwort family

Answer 54

- until recently the 8th largest family of angiosperms was Scrophulariaceae (aka figwort family), based on similarities in morphology - taxonomists recently investigated the evolutionary origins of the figwort family using cladistics and base sequencing - it was found that species in the figwort family were not a true clade and that 5 clades had incorrectly been combined into one.

Question 55

Porifera - symmetry - body cavity - segmentation - other features - examples

Answer 55

asymmetrical none (have pores) none have spicules for support sea sponge

Question 56

cnidaria - symmetry - body cavity - segmentation - other features - examples

Answer 56

radial mouth but no anus none stinging cells (cnidocytes) jellyfish, coral, sea anemone

Question 57

Mollusca - symmetry - body cavity - segmentation - other features - examples

Answer 57

bilateral mouth and anus non-visible (mantle and food) may have a shell (made by mantle) snail, octopus, squid, bivalves

Question 58

platyhelmintha - symmetry - body cavity - segmentation - other features - examples

Answer 58

bilateral mouth but no anus none flattened body (increase sa:vol ratio) tapeworm, planaria

Question 59

annelida - symmetry - body cavity - segmentation - other features - examples

Answer 59

bilateral mouth and anus segmented move via peristalsis earthworm, leech

Question 60

anthropoda - symmetry - body cavity - segmentation - other features - examples

Answer 60

bilateral mouth and anus segmented exoskeleton (chitin) insects, spiders, crustaceans

Question 61

vertebrate classes

Answer 61

fish amphibian reptile bird mammal

Question 62

fish - body covering - reproduction - breathing - temperature - other features

Answer 62

scales made out of bony plates external gills ectothermic have a swim bladder

Question 63

amphibian - body covering - reproduction - breathing - temperature - other features

Answer 63

moist skin external simple lungs and via skin ectothermic larval state in water, adult state on land

Question 64

reptile - body covering - reproduction - breathing - temperature - other features

Answer 64

scales made out of keratin internal (lays soft eggs) lungs with extensive folding ectothermic simple teeth with no living tissue

Question 65

bird - body covering - reproduction - breathing - temperature - other features

Answer 65

feathers internal (lays hard eggs_ lungs with bronchial tubes endothermic have wings and beaks with no teeth

Question 66

mammals - body covering - reproduction - breathing - temperature - other features

Answer 66

hair internal - live births (except monotremes) lungs with alveoli endothermic feed young with milk from mammary gland