Evolution – Biology HL PracticeTime allotted: 93 min 58 marks1. The barn swallow (Hirundo rustica) usually has one mate. A study was conducted to

examine mate selection in barn swallows.

The hypothesis was that females prefer to mate with males displaying longer tail feathers.Four groups of male birds were captured for study. The first group had its tail feathers shortened. The second group (control I) had its tail feathers shortened and the pieces reattached.The third group (control II) was unaltered. The fourth group had its tail feathers elongated by attaching the pieces removed from the shortened group.

Graph A below shows the mean length of time required by each group to attract a mate (pre-mating period). Graph B shows the reproductive success of each group of male birds ie the number of chicks that reached full development and were ready to fly (fledglings) by the end of the reproductive season. The vertical lines on both graphs indicate the variability of the data.

2 5

2 0

1 5

1 0

5

0

1 2

1 0

8

6

4

2

0

n u m b e r o f f le dg lin g s

P re-m a tin g p e rio d/ d ay s

sh o rten e d co n tro l I c o n tro l II e lo n g a te d

Tail trea tm en t

sh o rten e d co n tro l I c o n tro l II e lo n g a te d

Tail trea tm en t

G ra p h A

G rap h B

[Source: adapted from Moller reported in Evolutionary Analysis, by J C Herron (2001), Prentice Hall, New Jersey]

(a) Determine the difference in the mean pre-mating period for the elongated versus the shortened treatment groups.

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(1)

(b) State the relationship between tail length and the number of fledglings.

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(c) Suggest reasons for the difference in reproductive success of the shortened and elongated tail treatment groups.

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(d) Explain the conclusions that can be drawn from the data for control I and control II.

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(3)(Total 7 marks)

2. The bones of many modern birds and the fossils of bird ancestors have been compared. The body shape and how bird ancestors might have flown have been studied. This indicates that small predatory dinosaurs which lived on the ground

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evolved into birds with some flying capabilities. These then evolved into modern birds. The cladogram shows part of bird evolution and the drawings show anatomical structures linking birds to dinosaurs with hollow bones.

F ly in g C a p a b ilitie s

N o f ly in gcap ab ili ty

N o fly in g b u tp rey -se iz in gfo re lim b s tro k e ,flap p in g w in g s

F la p p in gflig h ts tro k e

M o rep o w erfu lflig h t

E n h a n cedflig h tm an o eu vrab ility

M o d ernflig h tcap a b ili tie s

Coelophysis

C oe lophysis

Veloc irap to r

Veloc irap to r

A rchaeop teryx

A rchaeop teryx

Ib erom eso rn is E nan tio rn ithes C o lum ba

Co lum ba

D in o sa u rs E a r ly b ird s M o d ern b ird s

W rist a n d h a n d

I I

I

I

IIII II IIII I

III II I

II I

IV

R e m n an to f V

D isk lik ew ris t b o n e

H a lf-m oo nsh ap ed w ris t

b o n e H a lf-m oo nsh ap ed w ris t

b o n e

[Source: Kevin Padian and Luis M Chiappe, (February 1998) Scientific American, pages 28-37]

(a) Identify which bird ancestor appears most closely related to dinosaurs.

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(b) Compare the flight capabilities and hand and wrist structure of Velociraptor and Columba.

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(c) Identify the two types of evidence for evolution shown by the data.

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(2)(Total 6 marks)

3. Tay-Sachs disease is an autosomal recessive disorder of the enzyme hexosaminodase. The disorder causes a build-up of fatty deposits in the brain. A child affected by the disease usually dies by the age of four. The frequency of Tay-Sachs disease (tt) in a Mediterranean population is 0.0003.

(a) Calculate the frequencies in the population of allele t and genotype Tt.

allele t:...............................................................................................

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genotype Tt:...............................................................................................

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(b) State two conditions required for the Hardy-Weinberg equation to be valid.

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(2)(Total 4 marks)

4. (a) (i) Outline the methods used by Miller and Urey in their experiments into

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the origin of organic compounds on Earth.

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(ii) Outline the conclusions that Miller and Urey drew from their experiments.

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(b) Darwin developed the theory that natural selection is responsible for the origin of species.

(i) Suggest two other theories for the origin of species.

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2. ........................................................................................................................

(2)

(ii) Discuss briefly the evidence for one of these two other theories.

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(3)(Total 9 marks)

5. The phylogeny below shows how and when vertebrates could have evolved. The lines show when each lineage arose, split and in some cases became extinct.

[Source: http://evolution.Berkeley.edud/evosite/evo101/IIEAAddingtime.htmlUC Museum of Paleontology’s Understanding Evolution (http://evolution.berkeley.edu).]

(a) Identify how many years ago mammals split from birds and reptiles.

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(b) State the evidence which allows scientists to know that Placoderms existed.

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(c) Birds and mammals are warm blooded. Discuss the hypothesis that some dinosaurs may have been warm blooded, using the phylogeny diagram opposite.

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(d) Outline how the geographical distribution of mammals has affected their evolution.

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(2)(Total 7 marks)

6. The evolution of groups of living organisms can be studied by comparing the base sequences of their DNA. If a species becomes separated into two groups, differences in base sequence between the two species accumulate gradually over long periods of time. The number of differences can be used as an evolutionary clock.

Samples of DNA were recently obtained from fossil bones of a Neanderthal (Homo neanderthalensis). A section of the DNA from the mitochondrion was chosen for study, as it shows a high level of variation in base sequence between different individuals. A section of the Neanderthal mitochondrial DNA was sequenced and compared with sequences from 994 humans and 16 chimpanzees. The bar chart below shows how many base sequence differences were found among humans, between the humans and the Neanderthal and between humans and chimpanzees.

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2 0

1 5

1 0

5

0

H u m an -H u m a n

H u m an -N e an d e rth a l

H u m an -C h im pF req u en cy o fn u m b e r o fd iffe ren ces / %

N u m b e r o f d iffe re n ce s in b ase se q u en ce

0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 6 5

[Source: Krings, et al., Cell, 1997, 90, pages 19–30]

(a) The number of differences in base sequence between pairs of humans varied from 1 to 24. State the number of differences shown by the highest percentage of pairs of humans.

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(b) Humans and Neanderthals are both classified in the genus Homo and chimpanzees are classified in the genus Pan. Discuss whether this classification is supported by the data in the bar chart.

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Data suggests that humans and Neanderthals diverged 550 000 to 700 000 years ago.

(c) If a sample of mitochondrial DNA was obtained from a fossil bone of Australopithecus, predict, with a reason, how many base sequence differences there would be between it and human DNA.

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(2)(Total 6 marks)

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7. Evidence from bones, teeth, soft tissues and molecular data support the view that modern humans and chimpanzees are particularly closely linked. A complete cranium (Sahelanthropus tchadensis) found recently in Sahel, northern Chad, Africa has contributed to this idea.

Part of the known fossil record of hominids is shown below. Extinct species are indicated with the dates of the earliest and latest fossil evidence. Species are assigned to one of five categories based on brain and cheek-tooth size, posture and locomotion.

Mill

ions

of y

ears

ago

[Reprinted with permission from Macmillan Publishers Ltd:Bernard Wood “Palaeoanthropology: Hominid revelations from Chad”, Nature, 418 (6894) pp.

133-135, © 2002.]

K ey :L arg e b ra in , sm all te e th , b ip ed a lism

S m a ll b ra in , v e ry la rg e tee th , facu lta tiv e b ip ed a lism (ab ility to w a lk o r ru n o n tw o leg s , o r a s a q u ad ru p ed , acco rd in g to th e c ircu m stan ces)

S m a ll b ra in , la rg e tee th , facu lta tiv e b ip ed a lism

S m a ll b ra in , sm a ll tee th , q u ad ru p ed a lism

In su ffc ien t ev id en ce

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(a) State the approximate age of the oldest Homo erectus fossil found.

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(b) State the possible age of the Sahelanthropus tchadensis fossil found recently.

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(c) Using the data in the graph, identify the largest number of hominid species that lived at the same time and name each one.

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(d) Discuss which genus is more closely related to Paranthropus.

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(e) Describe a method which can be used to determine whether S. tchadensis lived at the time when H. sapiens and P. troglodytes shared a common ancestor.

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(f) Outline the method used to accurately date the fossil found in Chad.

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(2)(Total 8 marks)

8. (a) State two conditions under which the Hardy-Weinberg principle applies.

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(b) State the full classification of humans.

Kingdom Animalia

Phylum I ................................................

Class Mammalia

II ................................................ III ................................................

Family IV ................................................

Genus Homo

Species sapiens

Sub-species sapiens(2)

(Total 4 marks)9. (a) Define half-life.

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(b) Discuss gradualism and punctuated equilibrium.

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(6)(Total 7 marks)

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