Classification and Evolution

Question 1

In 2006, the scientific journal, Nature, reported the discovery of a fossil from around 380 million years ago. It was given the name Tiktaalik roseae. This fossil has some features in common with fish and some features in common with amphibians.
Tiktaalik roseae is a member of the kingdom Animalia. The structure of its individual cells has not been preserved by fossilisation.
State two features of cells of an organism from the kingdom Plantae that would not have been present in the cells of T. roseae. (F212 June 14 q1b)

Answer 1

1 (cellulose) cell wall;
2 chloroplast; [plastids/ dictysomes / many small Golgi]
3 (large/ permanent) vacuole; [tonoplast]
4 starch granules; [druses/ raphides/ crystalline inclusions / Ca oxalate]

Question 2

Fossils provide strong evidence that organisms have evolved over time. Describe other types of evidence that support the theory of evolution. (5mks)
(F212 june14 q1c)

Answer 2

1) (similarities/ differences in) genes/ genetics/ DNA/
RNA/ molecules/ biochemistry; [molecular / biochemical evidence]
2) (similarities/ differences in) nucleotide/ base sequence/ order;
3) (similarities/ differences in) cytochrome c/ haemoglobin / ATP synthase/ RNA polymerase;
4) (similarities / differences in) sequence/ order , of amino acids (in proteins);
5) similarities between any of the above implies (close) relationship [if their genes are similar they must share a recent common ancestor; ‘chimps and humans share large proportion of DNA and this means that they are related gets mp 1 and 5]
6)idea of evolution within human history ; [in the context of an example of evolution in action, e.g. MRSA resistance to antibiotics or as a general statement; selective breeding (artificial selection) example]
7) similarities in / differences in / comparison of , embryology / morphology / anatomy / physiology / behaviour ; [e.g. similar finches occupying different niches on neighbouring Galapagos islands; e.g. vertebrate pentadactyl limb; idea of vestigial organs]

Question 3

common ancestor splits off to A then B, C, DExplain what the sketch shows about the relationship between organisms A, B, C, and D. [2mks]
[f212 jun 14 q5b]

Answer 3

1) B and C and D are more closely related (to each other
than to A);
2) A is in different (taxonomic) group (from other 3); [named taxonomic group]
3) B and C and D, share more, recent common ancestor;
4) phylogeny / evolution , of B and C and D diverged at same point

Question 4

In 1859, Darwin published his book,
On the Origin of Species , in which he explained how organisms evolve by natural selection:
• Darwin’s book caused controversy at the time of its publication
• his theory of natural selection is now widely accepted by scientists.
Why is natural selection now more widely accepted by scientists than it was in the
19th Century? (F212 june14 q5c)

Answer 4

fits evidence; idea of more, evidence / research (since nineteenth century)
[examples, e.g. DNA revolution / more fossils; improved technology / molecular evidence; changes in
religious belief]

Question 5

State the name given to the evolution of a new species. (F212 June 14 q5ei)

Answer 5

speciation

Question 6

Suggest why a higher number of species have evolved in the Galapagos Islands,
compared with an area of the same size on the South American mainland. (F212 june14 q5eii)

Answer 6

different islands have different, selection pressures / abitats / environments / vacant niches;
idea of isolation
[ the Galapagos have a wider range of habitats; e.g. the islands are separated from the mainland / no gene
flow / geographic barrier / reproductive barrier; allopatric (speciation) IGNORE sympatric]

Question 7

Allopatric (geographic) speciation

Answer 7

geographic speciation is speciation that occurs when biological populations of the same species become vicariant, or isolated from each other to an extent that prevents or interferes with genetic interchange.

Question 8

Sympatric speciation

Answer 8

the process through which new species evolve from a single ancestral species while inhabiting the same geographic region.

Question 9

Suggest why this lack of genetic variation might have contributed to the rapid spread of the disease. f212 june13 7ai

Answer 9

if one susceptible to, this/ the disease, all likely to be;

Question 10

Suggest why, despite the low genetic variation, the average yield of potato plants varied from year to year. f212 june13 7aii

Answer 10

1 environment/ environmental factor;
2 (variation in) weather conditions/ temperature; [climate]
3 rainfall / soil water content;
4 soil, (named) mineral / nitrate, content; [mineral availability / amount of fertiliser added]
5 (named) biotic factor (might vary); [e.g. number of pests / competition from other plants / disease]

Question 11

Some potato plants carry a gene that gives the plants resistance to potato blight. State the most likely cause of this genetic variation. f212 june13 7aiii

Answer 11

mutation; [deletion]

Question 12

Describe how it is possible to use selective breeding to improve the overall disease resistance of a crop, such as potatoes, in both the short and long term. (7mks) F212 june13 7b

Answer 12

1 cross / breed, with disease resistant variety; [make two disease resistant individuals reproduce]
2 method to test offspring for disease resistance; [ general statement or example e.g: ‘germinate seeds,
expose to disease, see if die’]
3 select , best offspring / offspring with resistance; [seeds/ tubers/ potatoes]
4 (inter)breed, offspring with resistance / best offspring;
5 (continue process) for (many) generations;
6 avoid breeding, closely related, individuals to preserve genetic diversity; [ avoid , inbreeding / inline breeding// ‘maintain genetic diversity by breeding with plants// from different field / area’// breed with different varieties to widen the gene pool]
7 (regularly back) cross with, wild variety;
8 preserving rare varieties in case they are needed in the future; [use of seed bank to preserve range of alleles]
9 [ e.g, ref. to marker assisted selection / detail of pollination method / prevention of self-pollination / asexual reproduction of desired variety]

Question 13

State the meaning of the term phylogeny and explain how phylogeny is related to classification. F212 june13 8b

Answer 13

1 (phylogeny is) evolutionary relationships
(between organisms); [phylogeny is evolutionary history]
2 (phylogeny is study of) closeness of (evolutionary) relationships; [phylogeny is the closeness of evolutionary relationships = 2 mks)
3 phylogeny is basis of / used in , natural / scientific / modern, classification; [new]
4 idea that the closer the (evolutionary or genetic) relationship the closer the (taxonomic) grouping; [ref to
recent common ancestors as AW for close relationship// named taxonomic group for ‘grouping’// ‘if the DNA is very different then the group is not the
same’]
5 correct use of example; e.g. gorillas and chimpanzees (closely grouped)]

Question 14

Water bears are extremely common in many habitats, including household gardens. However, they were not discovered until approximately 300 years ago.
Suggest reasons why they were not known before this time. F212 june13 8c

Answer 14

1) too small to see;
2) (unable to see them) until invention of microscope /
development of suitable viewing apparatus/ magnifying glass; [implication of being too small to see, e.g. ‘you need a microscope to see them’ = mp1// ‘people couldn’t see them in the past because we didn’t have microscopes’ = 2marks]
3) only 0.3mm in length; [± 0.1 mm]

Question 15

Living organisms can also be classified into three groups called domains.
Outline the features of this system of classification compared with the five kingdom system. 3mks f212 june12

Answer 15

based on (differences in) , DNA / RNA / nucleic acids /
polynucleotides;
idea that more accurately reflects origins (of, prokaryotes / eukaryotes);
(domain) divides / AW , prokaryotes; ora [
‘prokaryotes are split into groups because bacteria and
archaea are different’ = 2 marks (mp 3 and 4) ]
idea that domain reflects differences / AW , between
(eu)bacteria and archaea;
example of two differences to support point 3 or 4;
(domain) groups / AW , eukaryotes together; ora
idea that domain reflects the fact that there are
similarities between eukaryotic kingdoms;
example of two or more similarities to support point 6 or 7; [ e.g. all eukaryotes have, nuclei / membrane bound organelles / 80S ribosomes / large cell size / linear DNA / chromosomes / histones etc. ]

Question 16

Bats are the only mammals that can truly fly. Many species of bat hunt flying insects at night. Bats
are able to use sound waves (echolocation) in order to help them find their prey in the dark.
(a) Suggest how the ability to use echolocation may have evolved from an ancestor that did not
have that ability. 4mks f212 june12

Answer 16

natural/ directional, selection;
mutation;
(mutation / genetic variation, is) random / due to
chance / spontaneous / pre-existing;
selection pressure is lack of / competition for , food /
prey;
individuals with mutation(s) / allele(s) / gene(s) (for
echolocation) , survive; ora
(echolocation) allele(s) / gene(s) / mutation(s), passed on ( to next generation);
over many generations frequency of, echolocation/
allele / characteristic , increases;

Question 17

State two pieces of molecular evidence that can e used to identify organisms as belonging to different species. f212 june12

Answer 17

genetics / genes / DNA;
RNA;
amino acid sequences;
cytochrome C / fibrinopeptide/ haemoglobin;

Question 18

The soprano pipistrelle has an echolocation call that is ‘high pitched’ (between 52 and 60 kHz).
The common pipistrelle has an echolocation call that is ‘low pitched’ (between 42 and 47 kHz).
Variation within and between species can be as a result of genetic or environmental factors.
Whatever the causes of variation, the type of variation displayed can occur in two different
forms
Using the pipistrelle as an example, describe the key features of both forms of variation. 7 mks f212 june12

Answer 18

continuous:
(continuous / AW , is) effect of , many genes / polygenic / genes and environment / genetic and environmental /
environment;
quantitative:
there is a range / any value is possible / intermediate values / no distinct groups / AW;
example to illustrate any C marking point; [only , body mass / wingspan / colour / range of pitch within species]
discontinuous:
(effect of) one / few, genes;
little / no, environmental effect;
discrete categories / no intermediates / AW;
example to illustrate any D marking point; [low-pitched or high-pitched / pitch variation between species / sex
/ no bat call between 47 and 52 Hz]

Question 19

Suggest how the effects of insecticide use on a population of Anopheles mosquitoes could be easured and state the steps that should be taken in order to produce valid and reliable results. f212jan12

Answer 19

Field investigation:
(sampling) before and after insecticide treatment;
idea of, unbiased / random, sampling of population;
example of sampling technique;
(sampling in) different, times / weather;
large number of samples taken;
idea of standardised sampling procedure;
idea of preventing counting same individual more than
once;
idea of capture – recapture;
calculate mean / calculate standard deviation / apply
statistical test;
OR Laboratory investigation:
idea of: with and without insecticide exposure;
measuring mosquito survival / count surviving
mosquitoes;
controlling one named key variable;
controlling second named key variable;
idea of using a range of insecticide concentrations;
replicates;
calculate mean/ calculate standard deviation / apply
statistical test;

Question 20

Species that are more closely related in evolutionary terms have more genes in common
than species that are less closely related.
Using the information provided, suggest the likely genetic relationship between the three
parrot species. f212 jan12

Answer 20

1 all are in same family as all, are closely related; [
idea of link between family and close relationship must
be made]
2 kea and kaka are both, same genus / Nestor; ora for kakapo
3 kea and kaka, are more closely related /share more recent common ancestor, (than with kakapo);
4 kea and kaka have more genes in common / AW
(than with kakapo);
5 example of genetic similarity (between kaka and kea) evident from Fig 4.1; [ E.g. kaka and kea both brown / kaka and kea both have similar shaped beaks ]
6 differences between, kea and kaka / all three,
are great enough for each to be described as a different species;

Question 21

speciation f212jan12 4d

Answer 21

Name 1 speciation;
Mechanism – max 2 marks
2 isolation/ separation, (of populations);
3 further detail of isolating mechanism;
4 mutation / genetic variation;
5 natural selection / description of natural selection;
6 different selection pressure(s) (in different environment);
7 (enough) time to allow changes in populalion to prevent interbreeding;

Question 22

Outline the advantages of using a seed bank, as opposed to adult plants, in order to conserve an endangered plant species. f212jan12 cii

Answer 22

most plants produce an excess;
(so) can be collected (from wild) without damaging
(wild) , plants / organisms / population / habitat;
take up little space; ora
able to store, large numbers / more species; ora
easy / cheaper, to transport / AW; ora
idea of remaining viable for long periods; ora
less susceptible to, disease / pests / environmental
change; ora

Question 23

fossils;

Answer 23

fossils show that organisms have changed over time; [many fossil organisms dissimilar from modern
organisms]
idea that fossils or rocks can be dated; [fossils in chronological order]
idea of fossils showing intermediate forms / sequences;