Question 1
1
Rice (Oryza sativa) is usually intolerant to sustained submergence under water, although it grows rapidly in height for a few days before dying. This is true for one variety, Oryza sativa japonica. The variety Oryza sativa indica is much more tolerant to submergence. Three genetically modified forms of O. sativa japonica, GMFA, GMFB and GMFC, were made using different fragments of DNA taken from O. sativa indica. The plants were then submerged for a period of 11 days. The heights of all the plants were measured at the beginning and at the end of the submergence period.
14 marks
Question 1(c)
1(c)
Deduce the general relationship between the growth of all the japonica varieties and their stated tolerance level.
Mediumstructured1 marks
Answer
inversely proportional / the higher the tolerance, the less the growth / vice-versa
Question D1
D1
The diagram shows the range of heights and brain sizes found in four groups of hominids.
0 marks
Question D1(c)
D1(c)
Evaluate the hypothesis that an increase in hominid height makes an increase in brain size necessary.
Harddata_response3 marks
Answer
(hypothesis appears to be supported by the data as) H. sapiens has the greatest height and the largest brain size / H. floresiensis has smallest height and smallest brain size; the diagram shows a positive correlation/trend; (hypothesis not supported by the data as) H. erectus and H. sapiens almost the same height but different brain size / Australopithecus and H. floresiensis different height but similar brain size; Australopithecus has large height range but a small brain size range; fossil record incomplete/possible limited specimens; no causal connection established;
Question 1
1
Analysis of the genome of primates reveals many DNA segments that have been duplicated. It is possible to deduce the stage in evolution at which segmental duplications (SDs) occurred by comparing human and other primate genomes. Human-specific SDs occurred after humans and chimpanzees diverged. Human-chimpanzee shared SDs occurred after the common human-chimpanzee ancestor diverged from gorillas and so on. It is possible to estimate the rates at which SDs occurred during evolution using knowledge of when the primates changed. In the chart the bars indicate numbers of shared SDs and the line shows estimates of the rate of SDs per millions of years (Myr).
0 marks
Question 1(b)
1(b)
Outline the trends in the rate of SDs occurring since the separation of orangutans from other primates.
Mediumdata_response2 marks
Answer
increase after divergence (from 18 to 55 SDs per Myr ); further increase when diverged from gorilla; decrease when diverged from chimps;
Question 1(c)
1(c)
Explain how the number of human-chimpanzee shared SDs can be the lowest despite the rate of SDs per millions of years being the highest.
Harddata_response2 marks
Answer
these SDs occurred between the divergence of gorillas and the divergence of chimpanzees; this period was a shorter time than the others; some SDs lost again/deleted (after split from gorilla);
Question 1(d)
1(d)
A few SDs were found in humans and gorillas but not chimpanzees. Suggest how this might have occurred.
Harddata_response1 marks
Answer
same SDs occurred (independently) in both humans and gorillas; deletion of the SDs in chimpanzees;
Question 1
1
Bone tools found in the Swartkrans site in South Africa were thought to be used by Australopithecus robustus when digging for food. Using replica tools, researchers dug around plants for bulbs, dug in soil for larvae and dug in termite mounds for termites. They compared the scratch marks found on the replica tools with those on the original Swartkrans tool to predict the food eaten by A. robustus. The graphs below show the ranges of angles from the vertical position of the scratch marks and the ranges of widths of the scratch marks on each tool. The solid line on each bar represents the mean value for the range.
0 marks
Question 1(e)
1(e)
A. robustus was thought to have coexisted with Homo habilis, both becoming extinct at the same time. State approximately how many years ago A. robustus became extinct.
Mediumshort_answer1 marks
Answer
1.4 to 1.8 million years ago (accept answers within this range) ..... [1]
Question 1
1
Around 30000 species of vertebrate animals with four limbs (tetrapods) are found today. They are thought to have evolved from a single amphibian species that crawled on to land around 400 million years ago during the Devonian geological period. The graph shows how the number of families of tetrapod species varied in each geological period since their first appearance.
0 marks
Question 1(a)
1(a)
State in which geological period reptiles first appeared.
Easydata_response1 marks
Answer
Carboniferous [1]
Question 1(c)
1(c)
Analyse the data in the graph to conclude whether mammals are more likely to have evolved from birds or from reptiles.
Mediumdata_response1 marks
Answer
reptiles, as mammals appeared before birds
Question 1(e)
1(e)
The junction between the Cretaceous and Tertiary periods is called the K-T boundary. Using the data in the graph, discuss whether evolution at the K-T boundary fits the hypothesis of punctuated equilibrium or gradualism more closely.
Hardessay3 marks
Answer
punctuated equilibrium evolution occurs in rapid bursts / interspersed by long periods of stability; very little change in number of mammal/bird families occurred during Cretaceous period; but large increase during the Tertiary period; gradualism evolution occurs gradually; the number of amphibian/reptile families did not change much; number of families do not reflect what happens at species level / OWTTE;
Question 1
1
Evolution Canyon is a steep sided rocky valley near Mount Carmel in Israel. There are populations of fruit flies (Drosophila melanogaster) living on the north facing and south facing slopes of the canyon. Fruit flies are sensitive to drought conditions and die if they become desiccated. Twenty samples of fruit flies were collected from both sides of the canyon. They were subjected to the same conditions of drought stress and the life span (in hours) of the adult flies was measured.
0 marks
Question 1(a)
1(a)
Compare the data for the North and South-facing slopes.
Mediumdata_response3 marks
Answer
both show a (similar) range of life spans; both have a peak at 12-14 hours; SFS flies have higher mean life span than NFS flies / vice versa; (some) SFS flies live longer than 16 hours, NFS flies do not; (some) NFS flies live less than 10 hours, SFS flies do not;
Question 1(b)
1(b)
Genetic factors affect drought tolerance in Drosophila melanogaster. Deduce, with a reason, which of the slopes of the canyon has the drier climate.
Mediumdata_response1 marks
Answer
SFS has the drier climate as SFS flies live longer (when subjected to drought stress); both SFS and NFS have similar climates as both SFS and NFS flies have peak at 12-14 hours;
Question 1(c)
1(c)
Discuss whether the populations on the two slopes could evolve into two species.
Hardessay3 marks
Answer
NFS and SFS flies have different gene pools; abiotic differences between the two slopes create different selection pressures; genes/alleles for advantageous characteristics passed on from one generation to the next/become genetically different over time; may not mate / reproductive barriers/isolation leads to speciation; abiotic/geographical differences may not be sufficient to cause reproductive barrier; the gene pools may not be separated if flies can fly between sides of canyon/mix at base of canyon;
Question 1
1
Researchers investigating human evolution recorded energy use for the brain, gastrointestinal tract (gut), liver, kidneys and heart as a percentage of total energy used in the human body. They found that these organs use around 70 % of the body's energy although they account for only about 7 % of body mass. They also compared the mass of each of these organs in humans with other modern primates, each with a body mass of 65 kg as shown in the bar chart.
0 marks
Question 1(b)
1(b)
Compare the mass of human organs with the mass of other primate organs.
Mediumdata_response2 marks
Answer
a. total organ mass (approximately) same for both; b. very little difference in mass in heart/kidney/liver; c. human brain has greater mass than the primate brain; d. human gut has lower mass than the primate gut;
Question 1(d)
1(d)
Explain the differences between the organ size of humans and other primates in terms of trends in human evolution and their causes.
Harddata_response4 marks
Answer
a. brain size increased during hominid evolution / OWTTE; b. change in diet from mostly vegetarian to more protein-rich/meat eating diets; c. eating meat/protein allows larger brain growth / change in diet corresponds to the start of increase in hominid brain size; d. larger brains require more energy; e. larger gut necessary for plant material digestion; f. smaller gut is sufficient for meat/cooked food;
Question 1
1
The evolution of increased body size in mammals has been accompanied by an increase in life span. Another variable that could affect life span is brain size. Data was analysed from 47 mammalian species.
0 marks
Question 1(a)
1(a)
State the relationship between brain mass and maximum life span.
Mediumdata_response1 marks
Answer
as brain mass increases life span increases / positive/direct relationship/correlation
Question 1(d)
1(d)
Discuss how a larger brain size and longer life span might have contributed to the evolution of these species.
Hardessay2 marks
Answer
a. larger brain size allows for higher intelligence/better cognition/more complex brain functions; b. more efficient food finding / escape from predators; c. longer life span favours parental care / survival for more reproduction; d. (these advantages) favour natural selection which leads to evolution;
Question 1
1
There are many closely related Canis species in North America including the grey wolf (C. lupus), eastern wolf (C. lycaon) and western coyote (C. latrans). Hybridization can occur between members of these species. For example, during the last 100 years, hybridization has occurred between western coyotes (C. latrans) and eastern wolves (C. lycaon) in the area of Ontario shown by a star in the map shown below. Genetic evidence for hybridization is based on identification of haplotypes (combinations of linked alleles in clusters of similar genes) that exist in mitochondrial DNA (mtDNA) of Canis populations. The populations in this study were the Minnesota-northwestern wolf, southern Ontario coyote and northeastern coyote. Assume that all animals in each Canis population have the same mtDNA haplotypes. Key: Pie charts show the general locations and proportions of mtDNA haplotypes found in the populations.
0 marks
Question 1(d)
1(d)
The northeastern coyote has more wolf-like skull features than the southern Ontario coyote. Suggest a reason for this difference.
Mediumdata_response1 marks
Answer
northeastern coyote has greater proportion of C1/ haplotype from (eastern) wolf (than southern Ontario coyote)
Question 1
1
The land snail Cepaea nemoralis is very common in North America and in Europe. The base colour of its shell varies between brown, pink and yellow, and also in its intensity. Some shells are unbanded, but most show one to five bands of different width on top of the shell base colour. In the early 1950s, scientists studied the proportion of colours and banding of C. nemoralis in woods and fields near Oxford, UK, which differed in the type of plants and background colour. Each data point on the graph represents the percentage of yellow base colour shells and unbanded shells in a sample from either one type of wood or field, although other snail colours were present.
12 marks
Question 1(a)
1(a)
Determine the maximum percentage of yellow base colour shells found in woods.
Easystructured1 marks
Answer
78(\%) Accept answers ranging between 77 and 80 \%.
Question 1(b)
1(b)
Suggest either one possible advantage or one disadvantage of having a banded shell, stating whether it is an advantage or disadvantage.
Mediumstructured1 marks
Answer
advantage: camouflage OR disadvantage: visibility
Question 1(c)
1(c)
Using the data in the graph, distinguish between the distribution of C. nemoralis shells in woods and fields.
Mediumstructured2 marks
Answer
a. more yellow in fields (than in woods) / vice versa b. more unbanded in woods (than in fields) / vice versa c. more overlap within banding than within yellow colour OR yellow colour range greater than banding range d. very little overlap between fields and woods / some outliers Do not accept answers with only numerical data.
Question 1(d)
1(d)
The population of C. nemoralis has been studied for many years in open fields in a similar area. In the graph, each data point represents the percentage of adults of a given base colour plotted against the percentage of juveniles of the same base colour collected each year. Deduce from the data in the graph which shell base colours are on average most and least frequent among adult snails. Most frequent: Least frequent:
Mediumstructured2 marks
Answer
a. brown most frequent b. pink least frequent
Question 1(e)
1(e)
Discuss whether there is evidence in the data that colour plays a role in the survival of the snails.
HardEssay3 marks
Answer
Evidence that colour plays a role: a. few yellow adults (relative to juveniles) means that yellow juveniles do not survive into adulthood b. frequent brown adults (relative to juveniles) means brown juveniles survive well into adulthood Evidence that colour does not play a role: c. similar numbers of adult and juvenile pink individuals means pink colour does not play a role d. all three colours show wide variation/considerable overlap therefore evidence is not strong
Question 1(f)
1(f)
Using the theory of natural selection, explain the differences shown in the graph between the three colours of snail.
HardEssay3 marks
Answer
a. natural selection requires that snails become adults /live to reproduce their variations/undergo differential predation OWTTE b. higher adult frequency of brown shows selection c. but results for pink do not show selection d. more brown juveniles survive into adulthood showing that brown is selected for / vice versa against yellow e. not enough alone to support theory of natural selection but may be added evidence to similar observations in other organisms / OWTTE