Biology 12 Revision & practice exam questions. Multiple choice questions 1 The questions below relate to the following information. Data were obtained.

Biology 12 Revision & practice exam questions

Multiple choice questions 1 The questions below relate to the following information. Data were obtained relating to the rates of oxygen release and uptake in plants. The plants were placed for 12 hours in the dark followed by 12 hours in the light. Temperature was constant throughout the experiment. The results are shown in the graph. Which one of the following is the most accurate estimate of the total volume of oxygen used by the plants for respiration during the 24 hours of the experiment? (a) 50 cubic cm (b) 600 cubic cm (c) 1200 cubic cm (d) 1800 cubic cm

Multiple choice questions 2 The questions below relate to the following information. Data were obtained relating to the rates of oxygen release and uptake in plants. The plants were placed for 12 hours in the dark followed by 12 hours in the light. Temperature was constant throughout the experiment. The results are shown in the graph. What is the overall rate of oxygen production (cubic cm/hour) from photosynthesis at 20 hours? (a) 250 cubic cm/hour (b) 200 cubic cm/hour (c) 150 cubic cm/hour (d) 50 cubic cm/hour

Multiple choice questions 3 The questions below apply to the following diagram that shows part of an animal cell viewed under a microscope using a 10x ocular lens and a 40x objective lens. The nucleus was measured to be 20  m in diameter. What was the field diameter for the diagram above? a)10  m b)50  m c)100  m d)200  m

Multiple choice questions 4 The questions below apply to the following diagram that shows part of an animal cell viewed under a microscope using a 10x ocular lens and a 40x objective lens. Without changing anything else, the observer changed the revolving nosepiece of the microscope to a different magnification. This allowed the image of the entire cell to just fall within the field of view. The cell was then measured to be 200  m long. What was the magnification of the second objective used? a)5 x b)10 x c)20x d)80 x

Multiple choice questions 5 Which of the following statements about cell division is most correct? (a) Mitosis occurs during asexual reproduction. (b) Meiosis begins immediately after fertilization. (c) Mitosis explains why three brothers do not look alike. (d) Meiosis involves mutation of chromosomes. Some people have a muscle in their forearms called the long palmar muscle, whereas others do not. It is inherited by a single gene. Charles has a long palmar muscle but his parents do not. Charles' brother, Fred, does not have a long palmar muscle. Fred's wife Louise has a long palmar muscle and so do their two daughters. What is the mode of inheritance of the long palmar muscle? (a) recessive sex-linked on the X chromosome (b) recessive autosomal (c) dominant autosomal (d) dominant sex-linked on the X chromosome

Multiple choice questions 5 Which of the following statements about cell division is most correct? (a) Mitosis occurs during asexual reproduction. (b) Meiosis begins immediately after fertilization. (c) Mitosis explains why three brothers do not look alike. (d) Meiosis involves mutation of chromosomes. Some people have a muscle in their forearms called the long palmar muscle, whereas others do not. It is inherited by a single gene. Charles has a long palmar muscle but his parents do not. Charles' brother, Fred, does not have a long palmar muscle. Fred's wife Louise has a long palmar muscle and so do their two daughters. What is the mode of inheritance of the long palmar muscle? (a) recessive sex-linked on the X chromosome (b) recessive autosomal (c) dominant autosomal (d) dominant sex-linked on the X chromosome Charles

Multiple choice questions 6 Which of the following statements regarding marine and freshwater fish is true? (a) Freshwater fish produce small quantities of concentrated urine. (b) Marine fish produce large quantities of dilute urine. (c) Marine fish have osmotic water gain through the gills. (d) Freshwater fish take up salt ions through the gills. Which pair of cell components has the least relationship in terms of function? (a) nucleus - ribosome (b) centrioles - mitochondria (c) endoplasmic reticulum - Golgi body (d) plasma membrane - cell wall

Short answer Q34a & b 2006 Scientists have recently discovered that people who spend more time in 'deep sleep' at night have a different allele of the gene for the production of the enzyme adenosine deaminase. They have called this allele the 'slumber gene'. Adenosine builds up in the brain during the day as a product of the breakdown of ATP, ADP and other molecules involved in providing energy for cellular processes. During deep sleep, adenosine in the brain is broken down by adenosine deaminase. The enzyme produced by the slumber gene is less efficient than the normal enzyme and occurs in about 10% of the general population. (a)Provide an hypothesis to explain the variation in deep sleep amongst individuals that incorporates the function of adenosine deaminase. (b)(i) Give two characteristics of all enzymes (ii) In the case of the 'slumber gene', what is meant by the efficiency of enzyme action?

Short answer Q34a & b 2006 Scientists have recently discovered that people who spend more time in 'deep sleep' at night have a different allele of the gene for the production of the enzyme adenosine deaminase. They have called this allele the 'slumber gene'. Adenosine builds up in the brain during the day as a product of the breakdown of ATP, ADP and other molecules involved in providing energy for cellular processes. During deep sleep, adenosine in the brain is broken down by adenosine deaminase. The enzyme produced by the slumber gene is less efficient than the normal enzyme and occurs in about 10% of the general population. (a)Provide an hypothesis to explain the variation in deep sleep amongst individuals that incorporates the function of adenosine deaminase. Decreasing or low levels of adenosine deaminase (2 marks) increases time spent in deep sleep (2 marks) Varying efficiencies in versions of adenosine deaminase (2 marks) lead to variations in the amount of time in deep sleep (2marks) Increasing adenosine (2) results in increased deep sleep (2marks)

Short answer Q34b 2006 Scientists have recently discovered that people who spend more time in 'deep sleep' at night have a different allele of the gene for the production of the enzyme adenosine deaminase. They have called this allele the 'slumber gene'. Adenosine builds up in the brain during the day as a product of the breakdown of ATP, ADP and other molecules involved in providing energy for cellular processes. During deep sleep, adenosine in the brain is broken down by adenosine deaminase. The enzyme produced by the slumber gene is less efficient than the normal enzyme and occurs in about 10% of the general population b) (i) Give two characteristics of all enzymes Any two of: Most are proteins Denatured by high temperature/have an optimum temperature Substrate specific/active site/substrate specific/catalyses specific reaction pH sensitive/ have an optimum pH reusable function at low concentration reduces activation energy biological catalyst/catalyst/accelerate reactions (ii) In the case of the 'slumber gene', what is meant by the efficiency of enzyme action? The rate at which adenosine is broken down/reaction occurs more slowly How easily the enzyme-substrate complex forms/level of activation energy required

Short answer Q34c 2006 Scientists have recently discovered that people who spend more time in 'deep sleep' at night have a different allele of the gene for the production of the enzyme adenosine deaminase. They have called this allele the 'slumber gene'. Adenosine builds up in the brain during the day as a product of the breakdown of ATP, ADP and other molecules involved in providing energy for cellular processes. During deep sleep, adenosine in the brain is broken down by adenosine deaminase. The enzyme produced by the slumber gene is less efficient than the normal enzyme and occurs in about 10% of the general population. c)This part of the question refers to the axes below i) From the information provided on the efficiency of the two enzymes, sketch the relationship between adenosine concentration and time for each enzyme. Include a key (legend). (ii) Name one assumption that must be made for the comparison to be valid.

Short answer Q34c 2006 Scientists have recently discovered that people who spend more time in 'deep sleep' at night have a different allele of the gene for the production of the enzyme adenosine deaminase. They have called this allele the 'slumber gene'. Adenosine builds up in the brain during the day as a product of the breakdown of ATP, ADP and other molecules involved in providing energy for cellular processes. During deep sleep, adenosine in the brain is broken down by adenosine deaminase. The enzyme produced by the slumber gene is less efficient than the normal enzyme and occurs in about 10% of the general population. c)This part of the question refers to the axes below (ii)Name one assumption that must be made for the comparison to be valid. Any one of the following for 2 marks: same temperature same pH same starting concentration same enzyme concentration same substrate concentration i) From the information provided on the efficiency of the two enzymes, sketch the relationship between adenosine concentration and time for each enzyme. Include a key (legend). Curves labelled (legend) Curves correct with slumber gene above normal enzyme (no marks if any of the following: lines have different start points/lines increase across the whole graph (increase followed by decline is acceptable)/lines cross over slumber normal

Short answer Q34d 2006 (d)(i)In terms of DNA structure, explain what is meant by different alleles of a gene. (ii)How could the enzymes produced by two different alleles of the same gene be different in efficiency?

Short answer Q34d 2006 (d)(i)In terms of DNA structure, explain what is meant by different alleles of a gene. any two of: different base sequence in DNA/different nucleotide sequence leads to different triplet/codon diagram is acceptable: drawn difference in base sequence (1 mark) and linked to codons (1 mark) (d)How could the enzymes produced by two different alleles of the same gene be different in efficiency? Any two of: change of protein shape/different amino acid sequence leads to change of active site leads to different optimal pH

Short answer Q34e 2006 e) Adenosine deaminase removes a breakdown product of ATP. (i) Name two specific cellular processes requiring ATP. (ii) Predict, with an explanation, how deep sleep time might be affected the night after a person has studied 12 hours for an examination

Short answer Q34e 2006 e) Adenosine deaminase removes a breakdown product of ATP. (i) Name two specific cellular processes requiring ATP. Any two of: muscle action anabolism protein synthesis active transport growth/repair cell division/mitosis/meiosis DNA replication photosynthesis cell movement endocytosis/exocytosis/phagocytosis/pinocytosis transmitting nerve impulses bioluminescence (ii) Predict, with an explanation, how deep sleep time might be affected the night after a person has studied 12 hours for an examination Any two of: need for more deep sleep (to get rid of adenosine) and maximum one mark for either of: high activity level/concentration leads to high adenosine

Extended answers 1 2003 36a) Genetic information is stored in molecules of DNA. Using labelled diagrams describe the structure of DNA at the level of major components and describe how it carries genetic information. 1998 37b) From generation to generation information controlling the processes that occur in living cells is carried in DNA. Explain how the structure of DNA can carry information which can be accurately copied during cell division.

Extended answer 2003 36a) Genetic information is stored in molecules of DNA. Using labelled diagrams describe the structure of DNA at the level of major components and describe how it carries genetic information One mark/dot point in answers below unless otherwise indicated. Maximum 10 marks/question. Diagram – showing nitrogenous base pairs - A T, C G, and sugar phosphate backbone one mark for nitrogenous pairs label on the figure, 2 marks for sugar phosphate backbone label (3 marks total) nucleotides double helix one mark for correct basic structure in the figure name bases (one mark for naming all 4) indicate pairing (each correct pairing = one mark) sequence of bases codes for amino acid structure triplet code/codons relationship to amino acids

Extended answer 1998 37b) From generation to generation information controlling the processes that occur in living cells is carried in DNA. Explain how the structure of DNA can carry information which can be accurately copied during cell division. Diagram of DNA showing nucleotides (sugar, phosphate, nitrogen base) DNA molecule consists of chains of nucleotides parallel to each other Chains are held together by hydrogen bonds between bases There are 4 types of nucleotides due to 4 types of bases Adenosine will only bond to thymine, cytosine will only bond to guanine (base pairing rule) The information is carried within the DNA by the sequence of base pairs. Each segment of 3 nucleotides codes for one amino acid & is called a codon This information is copied to mRNA in the nucleus and carried to the ribosomes, determining which proteins are made The DNA replicates by splitting in 2, exposing the base pairs Free nucleotides within nucleus bind to the exposed bases, forming 2 exact copies Enzymes are involved in splitting the DNA and attaching new nucleotides

Extended answers 2 2002 36d) Most genes in the body carry information about the structure of enzymes, highlighting the importance of enzymes to cellular function. Describe the functions of enzymes in cells and explain why enzymes are so specific in their action. WATP 2004 37a) Pepsin is an enzyme that is released into the acidic environment of the stomach. Pepsin assists in the breakdown of protein to amino acids. Explain how changes in temperature and pH levels of the stomach will affect the action of pepsin in breaking down proteins.

Extended answer 2002 36d) Most genes in the body carry information about the structure of enzymes, highlighting the importance of enzymes to cellular function. Describe the functions of enzymes in cells and explain why enzymes are so specific in their action. Functions of Enzymes (max 7 marks): catalysis speed up reactions reduce activation energy synthesis / anabolism example digestion / catabolism example energy production example control of chemical pathways / energy production Enzyme Specificity: Caused by active site / 3D shape Formation of enzyme – substrate complex / lock & key model Good diagram of lock & key model Enzymes work within narrow pH ranges Enzymes work within narrow temperature ranges

Extended answer WATP 2004 37a) Pepsin is an enzyme that is released into the acidic environment of the stomach. Pepsin assists in the breakdown of protein to amino acids. Explain how changes in temperature and pH levels of the stomach will affect the action of pepsin in breaking down proteins Pepsin, being an enzyme, catalyses the breakdown of proteins to amino acids Pepsin will work most effectively at optimal pH And temperature Increases in temperature will denature enzymes as they are proteins Which will change their shape, which will alter the shape of the active site causing the substrate to no longer fit & therefore prevent protein from breaking down Decrease in temperature decreases kinetic energy & lead to less possible contact between proteins & enzymes Thus fewer amino acids being produced/reduced enzyme activity Altering pH will also change the shape of the active site Leading to fewer amino acids being produced/reduced enzyme activity Significant increases or decreases in pH will stop all enzyme activity

Genetics Problems 1 A scientist bred a tall pea plant with a dwarf pea plant. All 104 offspring were tall. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? A scientist bred a pea plant with yellow pods to a pea plant with green pods. All 118 offspring had green pods. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? A scientist bred a pea plant with round seeds with a pea plant with wrinkled seed. All 97 offspring had round seeds. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? A scientist bred a pea plant with yellow seeds to a pea plant with green seeds. All 121 offspring had yellow seeds. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring?

Genetics Problems 1 A scientist bred a tall pea plant with a dwarf pea plant. All 104 offspring were tall. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? Autosomal dominant/recessive – tall is dominant Original cross was TT x tt, so all offspring are Tt Crossing offspring Tt x Tt T t Genotypes: 1TT : 2Tt : 1 tt T TT Tt Phenotypes: 3 tall : 1 dwarf t Tt tt A scientist bred a pea plant with yellow pods to a pea plant with green pods. All 118 offspring had green pods. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? Autosomal dominant/recessive – green is dominant Original cross was GG x gg, so all offspring are Gg Crossing offspring Gg x Gg G g Genotypes: 1GG : 2Gg : 1 gg G GG Gg Phenotypes: 3 green : 1 yellow g Gg gg A scientist bred a pea plant with round seeds with a pea plant with wrinkled seed. All 97 offspring had round seeds. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? Autosomal dominant/recessive – round is dominant Original cross was RR x rr, so all offspring are Rr Crossing offspring Rr x Rr R r Genotypes: 1RR : 2Rr : 1 rr R RR Rr Phenotypes: 3 round : 1 wrinkled r Rr rr A scientist bred a pea plant with yellow seeds to a pea plant with green seeds. All 121 offspring had yellow seeds. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? Autosomal dominant/recessive – yellow is dominant Original cross was GG x gg, so all offspring are Gg Crossing offspring Gg x Gg G g Genotypes: 1GG : 2Gg : 1 gg G GG Gg Phenotypes: 3 yellow : 1 green g Gg gg

Genetics Problems 2 A scientist bred a long tailed rat with a short tailed rat. All 10 of the offspring had long tails. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 1 of these offspring with a short tailed rat? A scientist bred a black rat to a brown rat. All 18 offspring were black. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? A scientist bred a long haired rat with a short haired rat. All 6 of the offspring had short hair. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 1 of these offspring with a long haired rat? A scientist bred a white rat to a brown rat. All 7 offspring were white. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring?

Genetics Problems 2 A scientist bred a long tailed rat with a short tailed rat. All 10 of the offspring had long tails. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 1 of these offspring with a short tailed rat? Autosomal dominant/recessive – long is dominant Original cross was RR x rr, so all offspring are Rr Crossing offspring Rr x Rr R r Genotypes: 1RR : 2Rr : 1 rr R RR Rr Phenotypes: 3 long : 1 short r Rr rr A scientist bred a black rat to a brown rat. All 18 offspring were black. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? Autosomal dominant/recessive – black is dominant Original cross was RR x rr, so all offspring are Rr Crossing offspring Rr x Rr R r Genotypes: 1RR : 2Rr : 1 rr R RR Rr Phenotypes: 3 black : 1 brown r Rr rr A scientist bred a long haired rat with a short haired rat. All 6 of the offspring had short hair. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 1 of these offspring with a long haired rat? Autosomal dominant/recessive – short is dominant Original cross was RR x rr, so all offspring are Rr Crossing offspring to a long hair Rr x rr R r Genotypes: 2 Rr : 2 rr r Rr rr Phenotypes: ½ short : ½ long r Rr rr A scientist bred a white rat to a brown rat. All 7 offspring were white. a)What type of inheritance is this? b)What are the expected genotype and phenotype ratios expected from crossing 2 of these offspring? Autosomal dominant/recessive – white is dominant Original cross was RR x rr, so all offspring are Rr Crossing offspring Rr x Rr R r Genotypes: 1RR : 2Rr : 1 rr R RR Rr Phenotypes: 3 white : 1 brown r Rr rr

Pedigrees

Autosomal dominant Autosomal recessive Sex-linked recessive Autosomal recessive

Biology 12 Revision & practice exam questions. Multiple choice questions 1 The questions below relate to the following information. Data were obtained.

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Biology 12 Revision & practice exam questions. Multiple choice questions 1 The questions below relate to the following information. Data were obtained.

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