2020 LIFE SCIENCES Material

GRADE 12 MARCH MATERIALS 2020 NAME OF LEARNER: ____________________________________ SCHOOL: ______________________________________________

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https://ultradeep.co.za LIFE SCIENCES AUTUMN SCHOOL PROGRAMME TIME/DAY TOPICS: ACTIVITIES PROGRESS 21/03/2020 INVESTIGATIONS 22/03/2020 DNA CODE OF LIFE & DNA PROFILING 23/03/2020 MEIOSIS AND MUTATION 24/03/2020 HUMAN REPRODUCTION 25/03/2020 HUMAN REPRODUCTION AND EXAM TIPS 2 https://tvetpapers.co.za

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https://ultradeep.co.za DAY 1: INVESTIGATIONS ACTIVITY 1 (EC 2019) 4 https://tvetpapers.co.za

https://ultradeep.co.za Activity 2(SCE June P 1:2017) A scientific investigation was conducted with 20 cyclists to determine whether caffeine can increase stamina. The procedure was as follows: • The group of cyclists was given the first cup of coffee, containing no caffeine, to drink. • The group then had to cycle for as long as possible at the same speed. • They cycled around a 400 m track on level ground. • The group was given a second cup of coffee, containing caffeine, to drink before cycling for the second time. The table below shows the average time the group of cyclists was able to pedal after drinking decaffeinated coffee (coffee without caffeine) and drinking coffee with caffeine. TYPE OF COFFEE AVERAGE DURATION OF CYCLING (minutes) Decaffeinated coffee (250 mℓ with no caffeine) 82 Decaffeinated coffee (250 mℓ with no caffeine) 123 1.1.1 State the question that the scientists were trying to answer through this investigation. (2) 1.1.2 Identify the: (a) Independent variable (1) (b) Dependent variable and how it was measured (2) 1.1.3 What is the relationship between caffeine consumption and the stamina of the cyclists? (2) 5 https://tvetpapers.co.za

https://ultradeep.co.za 1.1.4 Explain the purpose of giving the cyclists decaffeinated coffee to drink during the investigation. (2) 1.1.5 The cyclists were NOT told whether or not the coffee they drank contained caffeine. Explain why the cyclists were NOT given this information. (2) 1.1.6 The procedure does not indicate how much time passed between each cycling exercise. Explain why this is an important factor to know. (2) (13) Activity 3 (JIT) 2. The graph below represents the results of an investigation which compares the conviction (number of people found guilty) of criminals with the use of DNA evidence and without the use of DNA evidence from 1989 to 2003. COMPARISON OF THE CONVICTIONS WITH THE USE OF DNA EVIDENCE AND WITHOUT THE USE OF DNA EVIDENCE, FROM 1989 TO 2003 50 Number of people found guilty 40 Convictions with 30 DNA evidence 20 (per 1 000 arrests) Convictions without DNA 10 evidence 0 1991 1993 1995 1997 1999 2001 2003 1989 Year [Adapted from http://www.mindfully.org] 2.1.1 Formulate a hypothesis for this investigation. (2) 2.1.2 State the dependent variable in this investigation. (1) 2.1.3 How many more successful convictions per 1 000 arrests were made in 2003 with the use of DNA evidence? Show ALL calculations. (2) 2.1.4 A DNA database is a collection of the DNA profiles of all the citizens of a country. Explain how you would use the information in the graph to convince the government to create a DNA database. (4) (9) 6 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 4 (NORTH WEST 2019) 7 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 5 3. An investigation was done by Grade 12 learners to determine which chickens grow faster: chickens that are selectively bred for laying eggs or chickens that are selectively bred for meat production. The following steps were carried out: 1. The learners bought 30 one-day-old chickens from a commercial supplier. Fifteen of the chickens had been selectively bred for laying eggs and 15 of the chickens had been selectively bred for meat production. 2. All the chickens were kept under the same environmental conditions. This included being fed the same chicken feed, made mostly from cereal grains and protein sources. 3. The chickens were weighed regularly for a period of 45 days. The results of the investigation are shown in the graph below. Live weight(grams) Age of chickens (days) [Adapted from www.chicken.org.au] 3.1.1 Formulate a hypothesis for this investigation. (2) 3.1.2 State the independent variable in this investigation. (1) 3.1.3 Calculate the percentage weight increase of the chickens that were selectively bred for meat between day 8 and day 45. Show ALL working. (2) 3.1.4 StateONE advantage of repeating the investigation with 100 chickens. (2) 3.1.5 State THREE factors that the learners should keep constant in this investigation. (3) 3.1.6 Write a suitable conclusion for the investigation based on the results in the graph.(2) (12) 8 https://tvetpapers.co.za

https://ultradeep.co.za Activity 6 ( P1 JUN 2016) 4.1 Research shows that the average age of first menstruation is influenced by socio-economic status as well as race. Scientists carried out an investigation to determine the average age of the first menstruation of the girls in a community. Their hypothesis was: The average age of first menstruation has decreased over time. 4.1.1 For the investigation, state the: (a) Independent variable (1) (b) Dependent variable (1) 4.1.2 Name THREE planning steps that had to be considered before carrying out the investigation. (3) 4.1.3 If the results show that the average age of first menstruation has remained at 12,9 years of age for the last 25 years, explain the implications for the hypothesis stated by the scientists. (2) Name TWO physical characteristics in girls which would indicate 4.1.4 the start of puberty. (2) (9) Activity 7 5.1 A group of learners conducted an investigation to determine to which blood group most learners in their school belong. They recorded the blood group of 120 learners from each grade. The results are shown in the table below NUMBER OF LEARNERS IN EACH BLOOD GROUP GRADE A B AB O 8 20 30 16 54 9 36 24 28 32 10 35 5 15 65 11 50 20 15 35 12 24 26 28 42 5.1.1 Formulate a hypothesis for this investigation. (2) 5.1.2 State THREE planning steps that should be considered before undertaking this investigation. (3) 5.1.3 Draw a bar graph, illustrating the blood group distribution of grade 11 Learners (7) 5.1.4 Using the information from the table, write a suitable conclusion for this Investigation (2) 5.1.5 Explain why blood group O occurs normally frequently in a population. (3) 9 https://tvetpapers.co.za

https://ultradeep.co.za DAY TWO DNA and DNA PROFILING ACTIVITY 1(F/S 2019) Activity 2 SCE JUNE 2017 1.1 The diagram below represents a single-stranded nucleic acid found in the nucleus. 1.1.1 Identify the molecule represented in the diagram. (1) 1.1.2 Identify: (a) Part X (1) (b) Sugar Y (1) 1.1.3 Describe the process of transcription. (5) 10 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 3 (NORTH WEST P2 2019) 2.2 Haemoglobin (protein in blood) is made up of two types of polypeptide chains. In people with sickle cell anaemia, one polypeptide chain has one amino acid which is different from the normal sequence. This is due to a mutation which produces the base sequence CAT instead of CTT in the DNA molecule of haemoglobin The table below shows the mRNA codons for some amino acids. mRNA base codons Amino acids CAU Histidine CAA Glutamine acid GUA Valine GAA Glutamic acid CUU Leucine GAU Aspartic acid 2.2.1 State what is meant by a mutation. (1) 2.2.2 What type of mutation is responsible for sickle cell anaemia? (1) 2.2.3 Explain your answer to QUESTION 2.2.2. (2) 2.2.4 Use the information providedas well as the table to determine the: (a) Amino acid present in a normal haemoglobin (1) (b) Amino acid present in sickle cell haemoglobin (1) 2.2.5 Explain the consequences if the bond between two complementary chains of DNA is not able to break during replication. (2) (8) 11 https://tvetpapers.co.za

https://ultradeep.co.za Activity 4 2.1 A species of bacteria contains a type of protein, called protein 1. A mutationoccurred which resulted in the formation of a second type of protein calledprotein 2, instead of protein 1. Scientists determined the amino acid sequence of each protein. They then used the amino acid sequence to find the DNA base sequences that coded for portions of these proteins. The results are shown in the tables below. 2.1.1 Give the: (a) DNA triplet for the third amino acid from the left in thesequence for protein 2 (1) (b) Codon for lysine (1) (c) Anticodon for serine (1) 2.1.2 Protein 1 is made up of 66 amino acids. How many of EACH of the following is involved in the formation ofthis protein? (a) Genes (1) (b) RNA nucleotides (1) (c) Codons (1) 2.1.3 Describe how the mutation caused a change in the structure of theprotein. (4) (10) 12 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 5 13 https://tvetpapers.co.za

https://ultradeep.co.za Activity 6 14 https://tvetpapers.co.za

https://ultradeep.co.za Activity 7.1 15 https://tvetpapers.co.za

https://ultradeep.co.za Activity 7.2 16 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 8 17 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 9 ( F/S 2019) 1.4 The diagram shows the process of protein synthesis 18 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 10 (DBE 2019 P2 NOV) 19 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 11 20 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 12 ACTIVITY 13 21 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 8 (F/S 2019) 22 https://tvetpapers.co.za

https://ultradeep.co.za Activity 9 (JUNE SCE 2017) 3.3. The diagram below shows a technique used in paternity testing. 3.3.1 Identify the technique shown above (1) 3.3.2 Which male is the biological father of the child? (1) 3.3.3 Explain your answer to QUESTION 3.3.2. (3) 3.3.4 State TWO other uses of this technique (2) (7) 23 https://tvetpapers.co.za

https://ultradeep.co.za DAY 3: MEIOSIS ACTIVITY 1( F/S 2019) 24 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 2 (EC 2019) 25 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 3(LIMPOPO 2019) ACTIVITY 4 (GAUTENG 2019) 26 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 5 1.1 Study the diagram below and answer the questions that follow. X Y 1.1.1 Name the process illustrated in the diagram. (1) 1.1.2 Provide a label for the part marked Y. (1) 1.1.3 Give ONE reason why the process mentioned in QUESTION 1.1 is important. (1) 1.1.4 Describe what happens during the process as shown in the diagram above. (3) (6) 27 https://tvetpapers.co.za

https://ultradeep.co.za ACTIVITY 6 (NORTH WEST 2019) 28 https://tvetpapers.co.za

https://ultradeep.co.za Activity 7 2. The diagram below shows a phase during meiosis. A B C 2.1.1 Identify part: (a) A (1) (b) B (c) C (1) (1) 2.1.2 Name the phase illustrated in the diagram above. (1) 2.1.3 How many chromosomes were present in the phase before the one shown in the diagram above? (1) 2.1.4 How many chromosomes would be found in each gamete at the end of this division? (1) 2.1.5 Explain why the diagram above is NOT representative of a cell from a human being. (2) 2.1.6 State ONE place where meiosis takes place in the human male. (1) (9) 29 https://tvetpapers.co.za

https://ultradeep.co.za Activity 8 3. Study the diagram provided below of a cell undergoing meiosis. 3.1 Identify the phase of meiosis shown in the diagram. (1) 3.2 Give a reason for your answer in QUESTION 5.1. (1) 3.3 Name the process that has occurred between the homologous chromosomes so that they look different in the diagram above compared to what they would have (1) looked like originally. 3.4 (3) Describe the events that occur in the process named in QUESTION 5.3 3.5 If this cell was a human cell how many chromosomes would be present in the (1) phase shown. (7) ACTIVITY 9 (DBE NOV 2019) 30 https://tvetpapers.co.za

ACTIVITY 10(MDE 2019) ACTIVITY 11 4.1 The diagram represents a cell at metaphase of meiosis I. 4.1.1 Draw a fully labelled diagram to represent ONE of the resulting cells at the same phase of meiosis II. (7) 31

ACTIVITY 12 2.1 The diagrams below represent two different phases of meiosis in an organism. DIAGRAM | DIAGRAM II 2.1.1 Identify: (a) A (1) (b) B (1) 2.1.2 Identify the phases represented by: (a) Diagram I (1) (b) Diagram II (1) 2.1.3 State the number of chromosomes that were present in the original cell at the start of meiosis. (1) 2.14 Give the name of the organ in a male where meiosis occurs. (1) 2.1.5 Describe the process responsible for the appearance of the chromosomes as shown in region C. (4) 2.1.6 Identify the phase of meiosis during which the process referred to in QUESTION 2.1.5 occurs. (1) 2.1.7 State TWO reasons why meiosis is important. (2) (13) 32

Activity 13 (North West P2 2019) 1.6 The diagram below represents the chromosomes at different stages of meiosis. The shaded chromosomes are maternal in origin and the un-shaded chromosomes are paternal in origin. A B C D E F 1.6.1 Writethe LETTER only that represents the following: (a) The pairing of homologous chromosomes (1) (b) Crossing over (1) (c) Chromosomes in anaphase II (1) (d) Chromosomes in metaphase I (1) (4) 33

ACTIVITY 14 (SCE 2018) 1.5 The diagrams below represent two phases of meiosis in an organism. A Diagram 1 Diagram 2 1.5.1 Identify the phase of meiosis represented in Diagram 1. (1) 1.5.2 Identify part: (a) A (1) (b) B (1) (c) ¢ (1) 1.5.3 State what happens to structure D in the next phase of meiosis. (1) 1.5.4 Name the process during which genetic material was exchanged, as shown in the diagrams above. (1) 1.5.5 State the consequence if the process named in QUESTION 1.5.4 does not occur. (1) 1.5.6 Give the number of chromosomes present in: (a) The original parent cell in this organism (1) (b) Ahuman cell in the same phase as that shown in Diagram 2 (a } 34

Day 4 - HUMAN REPRODUCTION ACTIVITY 1(EC 2019) 35

ACTIVITY 2 (EC 2019) 1.4 The diagram below represents the structure of the male reproductive system. 1.4.1. Label part: (a) G (b) F 14.2 Supply the LETTER and the NAME of the structures with the following (a) The part where the sperm cells mature (b) The structure that controls the temperature for sperm production 1.4.3 Describe the common function of parts A and B. 36 a) a) (2) (2) (2)

Activity 3 ACTIVITY 4 (Mpumalanga 2019) 37

23 The diagram below shows events in the ovary during the menstrual cycle in a 28 day cycle. 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 ACTIVITY 5 Identify: (a) Structure A (b) Process 1 Name the hormone responsible for process 1. A woman was given medication with high concentration of progesterone. Explain the effect of this medication on the ovarian cycle Give an observable reason which suggest that fertilisation did not take place after the process numbered 1. Ovariotomy is a term used to describe the surgical removal of only the ovaries. They can be removed due to certain illnesses such as cancer. Explain why a female who have done ovariotomy will not undergo menstruation. Draw a labelled diagram of the structure B. 38 (1) (1) (1) (3) (2) (4) (3) (15)

3.2 The diagram below represents an ovary showing some of the changes taking place during the ovarian cycle of a female. 3.2.1. Give the name of: (a) The process taking place at B (b) The hormone responsible for the process at B 3.2.2 If fertilisation does not take place, structure A degenerates. Explain the implications of this for the ovarian cycle. 3.3 Tabulate TWO differences in the composition of the blood in the umbilical vein and the umbilical artery. ACTIVITY 6 39 (1) (1) (3) (5) (5)

2.4 The diagram below shows how the ovaries and the uterus are changed by various hormones during the menstrual cycle. The diagram below is not drawn to scale. Day 1 Day 28 Pituitary gland Lining of the uterus 241 (i) | Name hormone V. (1) (i) Describe what effect hormone V has on the lining of the endometrium. (1) (ii) Explain the importance of the endometrium lining. (2) 242 With reference to the diagram: (i) | Name hormone xX. (1) (i) Give the functions of hormone X in the menstrual cycle. (2) 243 Give TWO visible reasons from the diagram that indicate that fertilisation did not take place during this menstrual cycle. @) Activity 7 40

Study the diagrams below showing the male and female reproductive systems 3.5.1 Identify parts A, B and F respectively (3) 3.5.2 State ONE function of each of the following A. The fluid produced by part C (1) B. Part E (1) 3.5.3 Name the type of gametogenesis that takes place in the female reproductive systems. (1) 3.5.4 State TWO functions of part H. (2) 3.5.5 Explain why is it necessary for part D to be ‘outside’ the body in males. (2) 10 ACTIVITY 8 41

ACTIVITY 9 3.1 The diagram below represents a developing foetus in the human body. 3.1.1 Identify the parts labelled: (a) X (b) Y (2) 3.1.2 State THREE functions of the fluid labelled Z. (3) 3.1.3 Explain how the part labelled V is structurally suited to perform its function during the process of birth. (2) 3.1.4 Name two systems in the baby's body that take over the functions of part W once the baby is born. (2) 3.1.5 Explain how the body prevents the development of another ovum while the foetus is developing in the human body. (2) (11) 42

ACTIVITY 10 (GAUTENG 2019) 21 The graph below represents the concentration of oestrogen, progesterone, FSH and LH in the blood of a mature woman over a 28-day cycle. The hormone levels of a mature woman over a 28 day cycle r) ® 4 ° E o 4 <£ - ° 3 > ® 4 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Days 2.1.1 From the graph, state on which day ovulation takes place. (1) 2.1.2 Give ONE visible reason from the graph for your answer to QUESTION 2.1.1 (2) 2.1.3. What has caused the increasing levels of oestrogen, as shown on the graph, from days 8 to 14? (2) 2.1.4 What is the function of oestrogen in the uterus from day 8 to 14 of the cycle? (2) 2.1.5 — (a) Did fertilization take place during the 28-day cycle as illustrated in the graph? (1) (b) GiveONE explanation for your answer to QUESTION 2.1.5 (a) (2) (10) 43

Activity 11 3.3 Study the graph below and answer the questions that follow. 3.3.1 Name the structure that produces: (a) Hormone 2. (1) (b) Hormone 3. (1) 3.3.2 On which day did ovulation occur? (1) 3.3.3 Give ONE reason for your answer to Q3.3.2 that can be deduced from the graph. (1) 3.3.4 What conclusion can be made if the level of Hormone 1 drops from day 23 to 28 as shown on the graph? (1) 3.3.5 One hormone which is essential in the menstrual cycle is not shown in the graph. (a) Name this hormone. (1) (b) Explain its role in the menstrual cycle. (2) 3.3.6 Describe the negative feedback relationship between the amount of Hormone 1 in the blood and the hormone named in Q3.3.5 (a). (2) (10) 44

Activity 12 2 udy the graph alow ahouing fh homonal oh 23: ony te wing suse: oa oe 282. Saxebe blown 45

Activity 13 QUESTIONS: 15 minute (Toten a eHow 211 ape) ‘Stuy to graph blow ofa mansouaeyew ante ntuenes oF seen 31. Onwneh say doce ovulation tas piace? o (ne evan ie when te eg cle rokasea) Botvosn whic days does monstuston ake lace? ‘Sits ONE nncton ot FSH rng me marervs! oe. 0 (Hint Team the tunetone of FSH and Li) Deserve the funciona estenchis between progestrone and FSH. (2) (Wnt ts the negative feedback meenanism tat sonal ovulation ‘nd mension, eke sue You K70W ‘Account othe cange nthe tices ofthe endonenl ning beeen (day 18 ond dy 21 8 3, Diertizaton tae place wit the 26-6 cl ilushaed he grape? (1) 37, Give TWO rensons fo: your answer o QUESTION 36, @ 46

Activity 14 ACTIVITY 15 (NORTH WEST 2019) 47

21 The diagram below represents a sperm. 21.41 Give a label for part A. (1) 2.1.2 Explain TWO ways in which the sperm is adapted to ensure effective movement towards the Fallopian tubes. (4) 2.1.3. Name part B and explain the consequences for reproduction if a sperm does not have it. (4) (9) ACTIVITY 16(GAUTENG 2019) 48

2.2 Study the following diagram of a human sperm cell. 2.21 2.2.2 2.2.3 2.24 2.2.5 2.2.6 ACTIVITY 17 ce 4 Nucleus B A 3 um Give a function of the enzymes that are contained in the structure that covers part C. Provide a name for label A. Explain how the structure of part A makes it suitablefor its function. State the name and function of the organelles found in part B- How does the male body ensure that sperm cells are not killed by acidic urine as they travel through the urethra? What temperature is most favourable for the production of sperm?

3.1 Study the diagram of a sperm cell. A B c D oo — 6 3.1.1 Give the LETTER only of the part that contains: (a) Many mitochondria (1) (b) A haploid number of chromosomes (1) 3.1.2 Explain the presence of a high number of mitochondria in the part named in QUESTION 3.1.1 (a). (3) 3.1.3 Describe spermatogenesis. (4) 3.1.4 A healthy sperm cell is able to swim about 5 mm per minute. If the distance from the cervix to the end of the Fallopian tube is 20 cm, how long will it take for the sperm cell to reach the ovum at the end of the Fallopian tube? Show ALL calculations. (3) (12) ACTIVITY 18 (SCE 2018 ) 50

2.1 The graph below shows the concentration of progesterone in a woman's blood during the early stages of pregnancy. Progesterone levels in a woman's blood during the early stages of pregnancy 45 ce) 39,5 £ 40 D> 33,4 £35 30 g 30 26,2 28 225 |~-21,6 = 20 2 2@ 15 % 10 S Fa 5 0 4 6 8 10 12 14 Gestation period (weeks) 2.1.1 Name TWO structures responsible for producing progesterone during pregnancy. 2.1.2 Describe the general trend in the change in progesterone levels in the woman's blood during the early stages of pregnancy. 2.1.3 Describe the negative feedback mechanism that occurs between progesterone and FSH during pregnancy. 2.1.4 State the importance of the negative feedback mechanism described in QUESTION 2.1.3. 2.1.5 Calculate the percentage increase in progesterone levels between week 4 and week 14. Show ALL calculations. 2.1.6 The woman's progesterone level in week 16 was 25 ng/mf. (a) Explain why this woman should be concerned about the decrease in progesterone levels. (b) Suggest ONE way in which this problem could possibly be treated by a doctor. 51 (2) (1) (2) (1) (3) (2) (1) (12)

ACTIVITY 19 ACTIVITY 20 (DBE 2019) 52

1.4 The diagrams below represent the structures of an ovum and a sperm. Ovum Sperm 1.4.1 Identify part: (a) A (1) (b) B (1) (c) ¢ (1) 1.4.2 Name the process involving meiosis that leads to the formation of an ovum. (1) 1.4.3 Write down only the LETTER of the part of the sperm that enters the ovum. (1) 1.4.4 Write down only the LETTERS of TWO parts that enable the sperm to move towards the ovum. (2) (7) 53

ACTIVITY 21(DBE NOV 2019) ESSAY QUESTIONS 54

Activity 01 Describe the interaction of FSH and progesterone in controlling the production of ova, and the development of a fertilised ovum until it embeds itself onto the uterus wall. Content: (17) Synthesis: (3) (20) Activity 02 Activity 03 NORTH WEST 2019 AVTIVITY 4 (SCE 2018) 55

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COMPLETE DOMINANCE e.g. two EXAMPLES OF GENETIC CROSSES INCOMPLETE DOMINANCE e.g. red flowered plants crossed with white flowered individuals with pure — breeding contrasting characteristics are crossed. plants P, phenotype Red x White Py phenotype Tall x Short RRx WW genotype = TT x Meiosis (Mendel's Law of Segregazon) Meiosis (Maendef's Law of Segregation) Gametes R w Gametes T t Gametes Fertilisation or R R Fertilisation or \| Gametes|T__|T we Rw | Rw t Tt Tt Ww RW [RW t Tt Tt Fy genotype: RW F, genotype: Tt Principle of dominance) Phenotype: Pink ‘ Phe - Tall \ {Ottepring nave Intermediate forms of traits of parents) «individuals of F, all display the dominant characteristic) CO - DOMINANCE e.g. Cows with white fur crossed Sex — linked diseases eg. Haemophilia cused by a recessive allele on with bulls with red fur- ne R w Fertilisation Gametes | R R w RW [RW F, genotype: RW w Rw [RW | Phenotype: Roan red and white) (Both alisies are equally Gominant and are expreesed In the phenotype} X-chromosome. Caused excessive biceding. Males have orty one X- chromosome — they mainly suffer trom this disorder. Cross a heterozygous mother with a naemopnifac father. Py phenotype Non ha jac x haemophiliac genotype XOX x Meiosis (Mendel's law of Segregazon) Gametes x" x" OX" y i Gametes | x" = Fertilization \/ or a aan a F, genotype: X"X"; xx" xy xty: LY xy Dty¥ phenotype: Two haemophi 1F +1): Two non-haemophiliac{1F + 1 M) 57

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