life sciences paper 1 learner guide july 2011

Life Sciences

Paper 1

Winter School 2011

4 July – 15 July

Learner’s Guide

Life Sciences Paper 1 Exam Revision Learner’s Guide Winter School July 2011

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Introduction: Have you heard about Mindset? Mindset Network, a South African non-profit organisation, was founded in 2002. We develop and distribute quality and contextually relevant educational resources for use in the schooling, health and vocational sectors. We distribute our materials through various technology platforms like TV broadcasts, the Internet (www.mindset.co.za/learn) and on DVDs. The materials are made available in video, print and in computer-based multimedia formats. At Mindset we are committed to innovation. In the last two years, we successfully ran a series of broadcast events leading up to and in support of the NSC examinations Now we are proud to announce our 2011 edition of Matric Exam Revision, which will begin with our Winter School in July. We’ve expanded the broadcast to support you in seven subjects - Mathematics, Physical Sciences, Life Sciences, Mathematical Literacy, English 1st Additional Language, Accounting and Geography. During our Winter School, you will get Exam overviews, study tips on each of the topics we cover, detailed solutions to selected questions from previous examination papers, short question and answer sessions so you can check you are on track and live phone in programmes so you can work through more exam questions with an experienced teacher. Getting the most from Winter School Before you watch the broadcast of a topic, read through the questions for the topic and try to answer them without looking up the solutions. If you get stuck and can’t complete the answer don’t panic. Make a note of any questions you have. When watching the Topic session, compare the approach you took to what the teacher does. Don’t just copy the answers down but take note of the method used. Make sure you keep this booklet for after Winter School. You can re-do the exam questions you did not get totally correct and mark your own work by looking up the solutions at the back of the booklet. Remember that exam preparation also requires motivation and discipline, so try to stay positive, even when the work appears to be difficult. Every little bit of studying, revision and exam practice will pay off. You may benefit from working with a friend or a small study group, as long as everyone is as committed as you are. Mindset believes that the 2011 Winter School programme will help you achieve the results you want. If you find Winter School a useful way to revise and prepare for your exams, remember that we will be running Spring School from the 3rd to 7th October and Exam School from 19th October to 22nd November as well.

http://www.mindset.co.za/learn


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Programme Outline The Mindset Winter School is designed to focus on two subjects each day. For each subject you will find the following sessions:

Examination Overview

This is a 15 minute session that gives details of what you can expect in each examination paper. Practical guidelines are also given on how to prepare for the day of the exam.

Topics Tips

In this session you will be given a 15 minutes summary of the key ideas you need to know, common errors and study hints to help you prepare for your exams.

Topic Session

An expert teacher will work through specially selected questions from previous exam papers.

Interactive Q & A

After every topic you will get the chance to test yourself.

Live Phone-in

This is your chance to ask your own questions. So submit your question to the Help Desk and we might call you back to help you live on TV. All questions you submit will be answered within 48 hours as normal.

Winter Broadcast School Schedule


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Topic 1: DNA, RNA and Meiosis Question 1 (DNA) The following is a representation of a portion of a DNA molecule. Study the diagram and answer the questions that follow.

1.1. Give TWO functions of DNA (2) 1.2. Provide labels for parts numbered 1 to 4 (4) 1.3. Exactly where in the cell would you expect to find this structure? (1) 1.4. Name the monomers of this molecule. (1) 1.5. Describe the type of bond found between G and 3. State the significance of

this type of bond. (3) 1.6. In terms of the structure represented in the diagram , explain what

a gene is. (2) [13]

.

1

2

4

C

G 3

A


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Question 2 (DNA) Adapted from September , 2010, Paper 1, Question 2.1. Very complex procedures were used by scientists to determine the finer details of the physical and chemical nature as well as the composition of DNA. Scientists used chemical analysis to provide evidence of the relationships among the nitrogenous bases of DNA. Study the information in the table and answer the questions that follow.

Question 2

Adapted from September , 2010, Paper 1, Question 2.1.

Samples

PERCENTAGE OF NITROGENOUS BASES

IN DNA SAMPLE

Adenine

(A)

Guanine

(G)

Cytosine

(C)

Thymine

(T)

Human

liver cells30.3 19.5 19.9 30.3

Yeast 31.7 (a) (b) 31.7

2.1 Compare the amounts of Nitrogenous bases in the sample of human liver

cells. (2) 2.2 Calculate the percentage of Guanine in the DNA sample of yeast. Show all

workings. (3) 2.3 The sequence of bases on a portion of one strand (template) of DNA is

ACGT. Draw a labelled diagram of the portion of the complete DNA molecule. (5)

[10]


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Question 3 (MEIOSIS) Adapted from September, 2010, Paper 1, Question 1.6. The diagram below represents stages in the process of meiosis. They are , however, not in the correct sequence. Study the diagram and answer the questions that follow.

3.1 Identify the stages B and C. (2)

3.2 Provide labels for 1 , 2 and 3. (3)

3.3 Name TWO places in the human body where meiosis would occur. (2)

[7]


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Question 4 (MEIOSIS) Adapted from November, 2010, Paper 1, Question 2.1. The diagram below represents an animal cell in a phase of meiosis

4.1 Label C and D. (2) 4.2 (a) Identify the phase represented in the diagram above. (1)

(b) Give a reason for your answer to QUESTION 4.2(a). (2) 4.3 Name the process which resulted in parts A and B being different from each

other. (1) 4.4 Describe how the process referred to in QUESTION 4.3 occurs. (3) 4.5 State the importance of the process named in QUESTION 4.3. (1) 4.6 (a) How many cells will be formed at the end of the first division of the cell

drawn in the diagram above? (1) (b) How many chromosomes will each daughter cell have when the cell, drawn in the diagram above, has completed meiosis? (1)

[12] Question 5 (DNA-RECOMBINANT TECHNOLOGY)) Adapted from September, 2010, Paper 1, Question 1.5. Read the passage below and then answer the questions based on it . “In 1973 U.S. biochemists Herbert Boyer and Stanley Cohen made the first recombinant DNA. They cut open plasmids (DNA rings) of the bacterium Escherichia coli using a restriction enzyme. Then they added a section of DNA from another plasmid and used ligase to join the two together to re-form the ring of DNA “ This technology was later used and applied to the production of human insulin using bacteria. (The insulin can then be used in the treatment of Diabetes mellitus). A diagrammatic representation of this process is shown below


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5.1 The steps involved in this process are listed below . The order is, however,

not correct. Place the steps in their correct sequence by writing down only the letters as they occur.

A The bacterial plasmid ring is cut. B The plasmid is inserted into an E.coli bacterium C Insulin is produced by the bacterium. D The DNA with the insulin gene is added, and the plasmid ring is joined up again. E Human DNA containing the insulin gene is copied. F Millions of bacteria are produced by repeated divisions

(6) 5.2 State how the “re-joining” of the plasmid is ensured. (1) 5.3 What is meant by a transgenic bacterium? (1) 5.4 In the past, the pancreas of certain animals was used to extract insulin. State

ONE disadvantage of using animal pancreas to treat Diabetes. (2) [10]


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Question 6 (DNA ANALYSIS) Adapted from September, 2009,(Kwa-Zulu Natal) Paper 1, Question 1.4. A company claimed that the burger patties that they produced were 100% beef . A rival company suspected that the first company was actually putting soya protein into their burger patties .This allowed them to sell patties at a cheaper price. The second company was losing a lot of money, so they sent the cheap patties to be analysed in a lab. The DNA profiles /fingerprints for the cheap patties, pure beef and soya protein are shown below. Study them and then answer the questions that follow

6.1 Explain what DNA profiling/fingerprinting is. (2) 6.2 Was the company truthful about the claim it was making? Explain your answer

using evidence from the DNA profiles/fingerprints. (3) 6.3 List THREE other ways in which the technology of DNA profiling /

fingerprinting is useful. (3) 6.4 List TWO other ways in which un-ethical people could abuse the use of DNA

profiling / fingerprinting technology. (2) [10]


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Question 7 (DNA /RNA) Adapted from November , 2010, Paper 1, Original Question Number 2.4 Analysis of DNA samples from a patient with an illness showed that there were two different types of DNA present .One was double stranded human DNA and the other was single stranded virus DNA. The two types of DNA were isolated and put into separate test tubes .The analyses of the nitrogenous base composition of each test tube is shown in the table below.

7.1 Which test tube (1 or 2) contains virus DNA? (1) 7.2 Explain your answer to question .7.1. (2) 7.3 Tabulate THREE structural differences between DNA and RNA. (7)

[10]

Nitrogenous Base Composition

Adenine Cytosine Guanine Thymine

Test tube 1 22.1 27.9 27.9 22.1

Test tube 2 31.1 31.3 18.7 18.9


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Topic 2: Evolution Question 1 Adapted from Nov, 2010, P2, 3.2 Lamarck based his theory of evolution on two principles, ideas or “laws”.

1.1 Name and describe TWO principles that Lamarck used to explain how evolution took place. (6)

1.2 Explain ONE reason why Lamarck’s theory is NOT accepted. (2) Question 2 Adapted from Nov, 2010, P2, 3.1 Read the following passage and answer the questions that follow. Thousands of wildebeest were migrating across the great plains of the Serengeti in Africa. Some of them were large, some small, some strong and some weak. Lions followed the wildebeest, catching and eating the slowest ones. Water was scarce and only the strongest were brave enough to stop to drink from the waterholes.

2.1 Identify ONE phrase in the passage which describes variation among wildebeest.

2.2 Explain how Darwin’s idea of evolution by natural selection can be applied to this passage.

Question 3 Adapted from March, 2010, P2, 2.2 Study the diagram of a duck's foot below

3.1 Ancestors of ducks did not have webbed feet. In terms of natural selection,

explain how the webbed feet could have evolved. (7) Question 4 Adapted from March 2011, P2, 3 Darwin noticed different species of tortoises on the Galapagos Islands. Two of these tortoises, which are drawn to scale, are show below.


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4.1 Tabulate TWO visible difference between the two species of tortoises. (5) 4.2 Suggest what tortoise 2 may eat that tortoise will not be able to eat. (1) 4.3 The two species of tortoises shown above live on different islands. Darwin

suggested that they might have evolved from a common ancestor. Explain how this could have occurred. (6)

4.4 Explain how Lamarck would have explained the long necks of the tortoises. (5)

Question 5 Adapted from Nov, 2010, P2, 3.4 Study the diagrams below showing a process of evolution. DIAGRAMS 1, 2 and 3 show the sequence of events that occurred in rabbit populations over many thousands of years.


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5.1 Name the evolutionary process represented by the sequence of events shown in DIAGRAMS 1, 2 and 3 above. (1)

5.2 Describe the process stated in QUESTION 5.1 using the diagrams above. (5) Question 6 Adapted from Mar, 2010, P2, 3.2 Study the following diagrams which show different stages (1 to 4) of a process in evolution.

6.1 Name the evolutionary process that resulted from the continental drift shown. (1)

6.2 Describe how the original of species A to become two species as indicated in the diagrams above. (5)

Question 7 Adapted from Exemplar, 2011, P1,Q4 The information and question below are based on natural selection. Antibiotics are used to kill bacteria that cause diseases. In 1972, there was an epidemic of typhoid in Mexico. Normally, an antibiotic called chloramphenicol cured it. This time the antibiotic did not work and more than 14 000 people died. Eventually, doctors found an antibiotic that did work.

7.1 Using your understanding of natural selection, explain why chloramphenicol did not control the epidemic mentioned above. (5)


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Question 8 Adapted from Exemplar, 2011, P1, 4.2 Study the information below on an investigation based on artificial selection and answer the questions that follow. In 1965, an investigation was started to find out if artificial selection could increase the milk yield of cows. In one set of cows, artificial selection for high milk yield was carried out in each generation. This set of cows was called the SELECTED LINE. In the other set of cows, there was no artificial selection. This set was called the CONTROL LINE. Both sets of cows were kept under the same conditions. The average milk yield from both sets of cows that were born in each year from 1965 to 1990 was recorded. The results are shown in the table below. YEAR OF COW’S BIRTH 1965 1970 1975 1980 1985 1990

Selected line: average milk yield (litre per kg)

7,2 8,2 8,8 10,0 9,7 11,0

Control line: average milk yield (litre per kg)

7,2 7,1 6,0 6,8 6,6 5,8

8.1 Plot line graphs, on the same set of axes, using the information in the table

above. (12) 8.2 Calculate the change in average milk yield (litre per kg) between 1965

and 1990 for the selected line. Show your workings. (3) Question 9 Adapted from March, 2010, P2, 1.4 The diagram below shows a phylogenetic tree based on DNA similarities. The percentage next to each branch shows the amount of difference in the genome (DNA nucleotide sequence) of the two relevant groups.


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9.1 From the diagram, determine how long ago the chimpanzees split from the line to humans. (2)

9.2 Which organism is most closely related to humans? (1) 9.3 Calculate the DNA similarity between the genome of the chimpanzee and the

human. (2) Question 10 Adapted from March, 2011, P2, 1.6 Differentiate between:

10.1 Homologous and analogous structures (3) 10.2 Inbreeding and outbreeding (3) 10.3 Study the basic plans of the forelimbs of two different vertebrates

shown below.

10 3.1 Are the above forelimbs homologous or analogous structures? (1) 10.3.2 Explain your answer to QUESTION 10.1 (2) 10.3.3 Using the labels on the forelimb of a human as a guide, give the names

of the letters A and B. (2) 10.3.4 State TWO ways in which the forelimb of the bat is adapted for flying.

(2)


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Question 11 Adapted from March, 2011, P2, 4.2 Study the image.

11.1 Identify each of the organisms that are represented by A and B (2) 11.2 Tabulate FOUR observable differences between the skulls of

organisms A and B. (9) 11.3 Which organism is bipedal for most of its adult life? (1) 11.4 Explain TWO possible advantages of bipedalism to the organism

referred to in QUESTION 11.3. (4) 11.5 Name any TWO similarities between organisms A and B. (2)

Question 12 Adapted from Exemplar, 2011, P1, 3.1 Diagrams A and B below illustrate the skulls of Homo sapiens and Homo erectus. The diagrams are drawn to scale.


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12.1 Which of the diagrams (A or B) represents the following: a. Homo sapiens (1) b. Homo erectus (1)

12.2 Tabulate TWO visible differences between the skulls in diagrams A and B that represent changes in the structure that characterises human evolution. (5)

12.3 Describe the significance of Homo erectus to the 'out of Africa' hypothesis. (3)

Question 13 Adapted from Nov, 2010, P2, 3.3 Study the diagrams below of the upper jaw, skull and the foot of two organisms A and B. The diagrams are NOT drawn to scale.

13.1 With regard to the drawings above: (a) Tabulate TWO visible differences between the upper jaws of organisms A and B. (5) (b) Name ONE visible difference between the feet of organisms A and B. (2)

13.2 Which organism (A or B) is more likely to be bipedal? (1) 13.3 Give a reason for your answer to Question 1 (2)


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Topic 3: Genetics Question 1 Adapted from March, 2010, P1, question 1.5 Study the family tree below which shows inheritance of the type of little finger over four generations of a family.

1.1 How many members of the family have straight little fingers? (1) 1.2 Is person F homozygous or heterozygous for the type of little finger? (1) 1.3 Which type of little finger is controlled by a dominant gene? (1) 1.4 Explain your answer to QUESTION 1.3. (3) 1.5 In the fourth generation of the family, what proportion will be female with 1.6 a straight little finger? (2) 1.7 Persons F and G are twins. Were they produced from a single fertilised 1.8 egg cell? (1) 1.9 Give TWO reasons based on the phenotype to support your answer

to QUESTION 1.6. (2)

Question 1

KEY:

- Male with straight little finger - Female with straight little finger

- Male with bent little finger - Female with bent little finger

Family tree showing inheritance of type of little finger


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Question 2 Adapted from November, 2010, P1, 4.1 Study the karyotype of a human below and answer the questions based on it.

2.1 Is this karyotype that of a male or a female? (1) 2.2 Give a reason for your answer to QUESTION 2.1. (1) 2.3 Name the genetic disorder that the individual with this karyotype has. (1) 2.4 Give a reason for your answer to QUESTION 2.3. (2)

Question 3 Adapted from November, 2010, P1, 1.4 The diagram below shows the offspring of crosses between a pure-bred black coat bull and a pure-bred white coat cow. The coat colours of the offspring of the first and second generations are also shown. Coat colour is controlled by two alleles, one for black and one for white coat colour.

Question 2

Karyotype of a person with a genetic disorder


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3.1 Use the letters B and b and state which gene is responsible for the following (a) Black coat colour (1) (b) White coat colour (1)

3.2 Which animal(s) (1 to 8) in the diagram must be homozygous for coat colour? (3)

Question 4 Adapted from March, 2010, P1, 3.1. In rabbits the dominant allele (B) produces black fur and the recessive allele (b) produces white fur. Study the table below showing the genotypes of four rabbits.

Rabbit 1 2 3 4

Genotype BB Bb Bb bb

4.1 What are the phenotypes for rabbits 2 and 4 respectively? (2) 4.2 State the genotypic ratio that is shown in the table above (1) 4.3 If rabbits 1 and 4 were mated together and had 12 offspring, how many of

these would you expect to be black? (1) 4.4 Rabbit 2 was allowed to breed with rabbit 3. Use a genetic cross to show the

possible phenotypes and genotypes of the F1 generation for fur colour. (6) Question 5 Adapted from March, 2011, P1, 4.2 The table below shows the percentage frequency of human blood groups in the populations of two different cities in South Africa.

Human blood groups

% frequency in population

City 1 City 2

A 25 45

B 20 10

AB 10 5

O 45 40

5.1 Which blood group has:

(a)The highest frequency in City 1 (1) (b)The lowest frequency in City 2 (1)

5.2 Plot the data in the table as bar graphs on the same system of axes. (10 Question 6 Adapted from November, 2010, P1, 4.3 The blood bank wants to carry out an investigation to determine the distribution of blood groups of 1 200 learners in a high school. They decide to use a sample to do their investigation in order to save costs and time. They also want to get a reliable result.


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6.1 State any FOUR planning steps that the blood bank should put in place to do this investigation, before they draw blood from the learners, using a syringe. (4)

6.2 State THREE precautions that the blood bank should take when drawing blood from the learners. (3)

Question 7 Adapted from March, 2010, P1, 3.3 Read the passage below and answer the questions that follow.

Vaccine-producing bananas Vaccinations protect people all over the world from diseases. Scientists are working on producing a genetically modified banana that will act as a vaccine against hepatitis B, a liver disease that affects more than 2 billion people worldwide. In future, many vaccines and other medicines may be given to people and other animals in easy-to-eat fruit and vegetables.

7.1 State THREE possible advantages of using bananas as a vaccine against diseases. (3)

7.2 Give THREE reasons why people might be against the use of genetically modified bananas. (3)

Question 8 Adapted from November, 2010, P1, 4.4 Describe what stem cells are, and give TWO sources from which human stem cells may be harvested. Also explain TWO arguments, with reasons, for the use of stem cells and TWO arguments, with reasons, against the use of stem cells in humans. (12) Synthesis: (3) Note: No marks will be awarded for answers in the form of flow charts or diagrams


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Solutions to Topic 1: DNA, RNA and Meiosis Question 1 (DNA) 1.1. DNA controls the functioning of the cell DNA controls protein synthesis and thereby the formation of proteins and

hormones. Stores hereditary information and transmits this information from one

generation to the next (mark first two) (2) 1.2.

1- Deoxyribose sugar/Sugar 2- Phosphate 3- Cytosine 4- Thymine (4)

1.3. In the nucleus / mitochondria (1) 1.4. Nucleotides (1) 1.5. A Weak Hydrogen bond. During the process of replication , these bonds break easily, so that each strand can act as a template for a new DNA Molecule. (3) 1.6. A gene is a sequence of nucleotides on a DNA molecule (2)

[13] Question 2 (DNA) 2.1. Adenine and Thymine are the same (30.3%) and Guanine and Cytosine are almost the same (19.5 and 19.9%). (2) 2.2. A + T = 31.7 + 31.7 = 63.4%

100 – 63.4 = 36.6% Guanine = 36.6 ÷ 2 = 18.3% (3)


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2.3

Any (5)

[10] Question 3 (MEIOSIS) 3.1. B- Anaphase 1

C- Prophase 1

[Do not credit if only anaphase /prophase is given] (2)

3.2 1- Chiasma/Chiasmata

2- Centromere

3- Chromosome (3)

3.3. Testes and Ovaries Mark first 2 (2)

[7]

Mark allocation:

Heading =

Correct complement base pairs: o 2 complementary base pairs correct o 4 complementary base pairs correct

Correctness of diagram: o Hydrogen bond o correct sugar phosphate sequence o 2 DNA strands/chains/double helix


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Question 4 (MEIOSIS) 4.1. C- Spindle/ Spindle Fibre/ Spindle thread

D- Homologous pair / Bivalent /Tetrad/ Homologues (2) 4.2. a) Metaphase 1 (1)

b) Chromosomes are lined up at the equator in homologous pairs. (2) 4.3. Crossing over (1) 4.4. Homologous chromosomes pair up during prophase 1 of meiosis. The

chromatids facing each other with cross at points called chiasmata. An exchange of genetic material will occur between facing chromatids. (3)

4.5. It promotes genetic variation in the gametes (1) 4.6. a) 2

b) 2 (2) [12]

Question 5 (DNA RECOMBINANT TECHNOLOGY) 5.1. E A D B F C or A E D B F C (6) 5.2. A ligase enzyme is used to bond the two sticky ends together. (1) 5.3. A bacterium that has had its genetic make-up/gene sequence/DNA changed. (1) 5.4. Extraction from the pancreas is a time consuming process It is a very

costly procedure. People may be opposed to using animal products for religious / cultural / ethical reasons. Some individuals may have an allergic reaction to the animal product.

Mark first one (1x2) (2)

[10]

Question 6

6.1. Since no two people (except identical twins) have the same DNA sequence ,it is possible to use the DNA sequence to identify an individual. (2) 6.2. No. The cheap patties actually match exactly with the Soya and not at all with the beef (3) 6.3. Identification of a crime suspect Location of missing family members Paternity testing Identification of corpses (Mark first 3) (3)

6.4. Unethical individuals could “frame” other individuals by placing samples of

their DNA at the scene of a crime. They could swap laboratory samples used in forensics tests or paternity

tests (2) [10]


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Question 7 7.1. Test tube 2 (1) 7.2. Percentage of A does not equal T and percentage of C does not equal G in

test tube 2 , therefore it is evident that no base-pairing has occurred

OR

The percentages of A is equal to T and C is equal to G in test tube 1, therefore base pairing has occurred. Therefore test tube 2 contains the single stranded DNA molecule. (2)

7.3.

DNA RNA

1.Double stranded molecule/paired bases

1. Single stranded molecule /unpaired bases

2. Contains Deoxyribose sugar 2. Contains Ribose sugar

3. Contains nitrogenous base Thymine 3. Contains the Nitrogenous base Uracil

3. A is proportional to T ;and G is proportional to C.

4. Different relative numbers of A,T,G & C

5. A Longer molecule 5. A Shorter molecule

6. Helix /Helical in shape 6. Straight /non-helical structure

(Any 3x2) + 1 (Table) [10]


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Solutions to Topic 2: Evolution Question 1 Early Theories 1.1 *Principle of use and disuse/adaptation to the environment * compulsory mark - Structures of individuals in a population that are used more frequently became better/adapted - Structures of individuals in a population that are used less Frequently becomes smaller/disappear max *Principle of inheritance of acquired characteristics * compulsory mark - Acquired characteristics developed by the organism in its lifetime are passed on to its offspring (6) 1.2 Acquired characteristics are not inherited/do not cause any change to the DNA of an organism's gametes (sperms or ova) OR Organisms did not evolve because they wanted to evolve/ Lamarck’s theory is deterministic (2) Question 2 Early theories 2.1 “some large, some small” / “some strong and some weak” (1) 2.2 - Variation in the wildebeest population* (1) slow and weak, some large and strong were eaten by the lions survive and do not pass on and pass on their their characteristics to favourable characteristics to their offspring max 3 (3) - If this process continues from generation to generation the characteristic of the population will change* (1) * compulsory marks Question 3 Natural Selection 2.1 - There was variationwith regard to the feet within the ancestral duck populations - Some ancestral ducks had skin attached between the toes - As food became scarce/environment changed - Competition for food increased - Those ducks which had skin attached between their toes/ desired characteristic could swim better - To secure food and survived - Those ducks that did not have skin attached between their toes were unable to swim well- Did not secure food and died - Through natural selection entire populations of ducks with webbed feet evolved any (7)


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Question 4 Speciation 4.1

4.2 Tall plants/shrubs/small trees 4.3 - On each island there was variation (long and short) in the population of

tortoises lived under different environmental conditions different sources of food - After a period of time each group of tortoises underwent natural selection independently - On each island only those tortoises with the characteristics (long or short neck) favourable for its own conditions survived - Continued natural selection resulted in each island having tortoises that are very different from each other/ they differed genotypically and phenotypically - Reproductive isolating mechanisms prevented them from interbreeding even if they are allowed to mix i.e. each is a separate/new species any (6)

4.4 Lamarck would have explained the long necks of the tortoises as follows: All tortoises had short necks They needed to reach the taller trees and shrubs They thus stretched their necks repeatedly Their necks became longer - Law of Use They passed this acquired characteristic to their offspring Therefore all tortoises have long necks any (5) Question 5 Speciation 5.1 Speciation (1) 5.2 - In diagram 1 the rabbits were able to interbreed/genes can flow freely in

the population - In diagram 2 the two populations were separated by the river/geographic barrier

- The two populations cannot interbreed/no gene flow - Within each of the two separated populations there was variation

- Each group underwent natural selectionindependently as a result of varying environmental conditions


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- Each group becomes genotypically and phenotypicallydifferent - In diagram 3 the geographic separation no longer exist

- but the two populations do not interbreed/no gene flow even though they can mix

- because of the presence of reproductive isolating mechanism - They are now 2 different species any (5) Question 6 Speciation 6.1 Speciation (1) 6.2 The population of species A has split up into two The sea forms a physical

barrier and each group adapts to the new environmental factors Each group undergoes natural selection independently and develops separately Each group may become genotypically and phenotypically different Might prevent them from interbreedingwhen they come into contact again/become reproductively isolated leading to the formation of a new species (5)

Question 7 Present times 7.1 - There is a large degree of variation in the bacteria population

- When chloramphenicol was first used, it killed off a large number of bacteria - But some bacteria were resistant to chloramphenicol and survived - Those that survived were able to reproduce - Increasing the population of resistant bacteria - Continued use of chloramphenicol had little effect on the resistant bacteria - Hence the disease reappeared max

(5)


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Question 8 Artificial Selection 8.1

NOTE: If the wrong type of graph is drawn: - Marks will be lost for 'correct type of graph' If graphs are not drawn on the same system of axes: - Mark the first graph only using the given criteria Rubric for the mark allocation of the graph

Correct type of graph 1

Caption for graph 1

Correct label for X-axis 1

Graphs labelled/key provided for 2 graphs

1

Correct label for Y-axis 1

Appropriate scale for X-axis 1

Appropriate scale for Y-axis 1

Plotting 1 – 1 to 2 points plotted correctly

2 – 3 to 4 points plotted correctly 3 – 5 to 7 points plotted correctly 4 – 8 to 10 points plotted correctly 5 – 11 to 12 points plotted correctly

(12) 8.2 11, 0 – 7,2 = 3,8 litres/kg (3)

Comparison of the average milk yield in two sets of cows from

1965 to 1990

0

2

4

6

8

10

12

1965 1970 1975 1980 1985 1990

Year of Cow's birth

Av

era

ge

milk

yie

ld in

litr

es

/kg

Selected Control


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Question 9 Evidence – Biochemistry 9.1 5 mya (2) 9.2 Chimpanzee (1) 9.3 98,6% (2) Question 10 Evidence & Terminology 10.1 Similar structures

Homologous – that evolved from a common ancestor Analogous – that evolved from different ancestors (3)

10.2 Reproduction between organisms

Inbreeding – that are closely related Outbreeding – are not closely related (3)

10.3.1 Homologous (1) 10.3.2 Are similar in structure (slightly different function) suggesting a

similar/common origin/ancestor max (2) 10.3.3 A - Humerus B - Metacarpals/phalanges /carpals (2) 10.3.4 - There is a wing/web of skin between the metacarpals /skin - Forelimb and metacarpals are thin /light - Forelimb and metacarpals are long - Has a large surface area (Mark first TWO only) (2) Question 11 Human evolution 11.1 A – Gorilla B – Modern human (2) 11.2

11.3 B (1)


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11.4 - Allows total awareness of the environment in sensing danger/looking for food - Enables hands to be free to use implements/carry objects or offspring/throw/protect - Exposes a large surface area for thermo-regulation/lose body heat to surroundings in hot conditions/reduce overheating therefore reduce need for water

- Display of male/female sex organs as part of courtship behaviour (any 2 x 2) 11.5 - Capable of upright posture - Long upper arms - Freely rotating arms - Elbow joints allowing rotation of forearm - Rotate hands at least 180º - Flat nails instead of claws/bare finger tips - Opposable thumbs/which work in opposite direction to their fingers - Large brains/cranium compared to their body mass - Eyes in front/binocular vision/stereoscopic vision - Eyes with cones/colour vision - Sexual dimorphism/distinct differences between male and female - Olfactory brain centres reduced/reduced sense of smell

- Parts of the brain that process information from the hands and eyes are enlarged

- Two mammary glands only (Mark first TWO only) (2) Question 12 Human evolution 12.1 (a) B (1) (b) A (1) 12.2

Diagram A Diagram B

1 Brow ridges more pronounced 1 Brow ridges less pronounced

2 Smaller cranium/brain 2 Larger cranium/brain

3 Jaw protrudes (prognathous) 4 Not prognathous

4 No obvious chin 5 Pronounced chin

5 Elongated cranium 3 Shorter cranium

6 Zygomatic arch well developed 6 Zygomatic arch less developed

1 mark for table + (2 x 2) (5) 12.3 -H.erectus was the first Homo species to move out of Africa.

-Their large bodies and well adapted pelvic girdles made them better bipedal runners and walkers over long distances than H.sapiens (3)

12.4 -Large brains/skulls compared to their body mass -Olfactory brain centres reduced/reduced sense of smell


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-Parts of the brain that process information from the hands and eyes are enlarged -Eyes in front/binocular vision/stereoscopic vision -Eyes with cones/colour vision -Freely rotating arms -Long upper arms -Elbow joints allow rotation of forearm -Rotate hands at least 1800 -Flat nails instead of claws/bare finger tips -Opposable thumbs which work in opposite direction to their fingers -Upright posture -Sexual dimorphism/distinct differences -Two teats only (Any 4 x 1) (4)

Question 13 Human evolution 13.1

(b) Differences in Feet In A the big toe is close to the other 4 smaller toes/faces forward

In B the big toe is apart/opposable from the other 4 smaller toes/points outwards

OR In A the heel bone is relatively larger and in B it is relatively smaller OR In A the bones in the foot are straight and in B they are curved OR

In A phalanges are relatively shorter and in B they are relatively longer any 1 x 2

(Mark first ONE only) (2)


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13.2 A (1) 13.3 Foramen magnum in more towards centre of skull in A OR Foramen magnum in more towards the back of skull in B (2)


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Solutions to Topic 3: Genetics Question 1 [Pedigree chart] 1.1 10√ (1) 1.2 Heterozygous√ (1) 1.3 Bent little finger√ (1) 1.4 Only two parents showing dominant features√ can produce offspring showing

both√ phenotypes√ / bent and straight little finger√ OR Two parents with straight little fingers√ must be homozygous recessive√ to produce offspring all with only straight little fingers√ (3)

1.5 25 √% √ / 1/4 (2) 1.6 No√ (1) 1.7 - G is male and F is female√ / different sexes/ non-identical/ fraternal - F has a bent little finger and G has a straight little finger√ (2) Question 2 [Karyotype] 2.1 Female√ (1) 2.2 Has two X chromosomes√ /XX / chromosomes number 23 are similar/ No Y chromosome (1) 2.3 Down's√ Syndrome/ trisomy 21 (1) 2.4 Carries 3√ chromosomes on number 21√ (2) Question 3 [Pedigree chart] 3.1 (a) B√ (1) (b) b√ (1) 3.2 1√ 2√ 8 √ (3)

(Mark first THREE only) Question 4 [Monohybrid] 4.1 2 - Black√ 4 - White√ (2) 4.2 1BB:2Bb:1bb√ / 1:2:1 (1) 4.3 12√ / all / 100% (1) 4.4 (Remember use format) P1 phenotype Black x Black√ Genotype Bb x Bb√ Meiosis G B b x B b Fertilisation F1 genotype BB Bb Bb bb√ Phenotype Black and White√ Parents and offspring√ / P1 & F1 Meiosis and fertilisation√


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OR

gametes B B B BB Bb b Bb Bb

(1 mark for correct gametes, 1 mark for correct genotypes) Question 5 [Blood groups] 5.1 (a) O√ (1) (b) AB√ (1) 5.2

OR


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NOTE: If the wrong type of graph is drawn: marks will be lost for 'correct type of graph'. If graphs are not drawn on the same system of axes, mark the first graph only using the given criteria. Question 6 [Blood banks] 6.1 Get parental consent√ / permission from education department Determine what sample size is appropriate√

Random sample must be taken√ Arrange for all necessary equipment √ / personnel/ budget needed to be available Inform school of the day and time√ that the research will take place Draw up a table√ / recording sheet to record information (4)

(Mark first FOUR only) 6.2 Personnel should wear gloves√

Use new syringes√ / lancets/ cotton wool etc. for every learner tested Have written parental consent from each learner in the sample √ (3)

(Mark first THREE only)

Question 7 [Genetic engineering] 7.1 Available worldwide√

Children / people like to eat it√ Nutritious √ / contains carbohydrates, vitamins, etc. Can be locally grown√ (3)

(Mark first THREE only) 7.2 Risk to human health not yet known√

Religious objection to genetic engineering√ Do not eat bananas/ allergic to bananas√ Increase price of bananas√ Shelf life of bananas / vaccine√ (3)

(Mark first THREE only)


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Question 8 Stem cells Possible answer: rise to different types of cells (2) Source: Embryo / frozen embryo√ Blood in umbilical cord / cord blood√ Placenta√ Bone marrow√ (2)

(Mark first TWO only) Arguments for use of stem cells - Provide replacements for tissues√ damaged by age√ / trauma/disease -Used for research√ to see whether it can cure different diseases √ e.g. cancer -Stem cells from e.g. the blood from the umbilical cord can be stored√ when needed in future because it would no be rejected√ by the body's immune system any 2 x 2 (4)

(Mark first TWO only) Arguments against use of stem cells

- Expensive research money could be used for other need - Only rich people / expensive can afford to store stem cells for later use - Interfere with creation / Immoral we cannot play God / Relgion / Cultural - Can lead to illegal trade in the placentas of new-born babies to make - Money - Babies conceived and then aborted / abandoned / unwanted to use the stem cells from the placenta any 2 x 2 (4)

(Mark first TWO only)

Synthesis (3) (15)

life sciences paper 1 learner guide july 2011

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