Biology 12

Revision & practice exam questions

Multiple choice questions 1The 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 1The 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 2The 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 2The 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 3The 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 3The 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 4The 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 4The 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.

Multiple choice questions 5Which 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.

Multiple choice questions 6Which 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

Multiple choice questions 6Which 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 2006Scientists 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 2006Scientists 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 2006Scientists 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 enzymesAny 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 slowlyHow easily the enzyme-substrate complex forms/level of activation energy required

Short answer Q34c 2006Scientists 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 2006Scientists 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: lineshave 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 2006e) 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 informationOne 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 otherChains are held together by hydrogen bonds between basesThere are 4 types of nucleotides due to 4 types of basesAdenosine 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 codonThis information is copied to mRNA in the nucleus and carried to the ribosomes,

determining which proteins are madeThe DNA replicates by splitting in 2, exposing the base pairsFree nucleotides within nucleus bind to the exposed bases, forming 2 exact copiesEnzymes are involved in splitting the DNA and attaching new nucleotides

Extended answers 22002 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 productionEnzyme 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 acidsPepsin will work most effectively at optimal pHAnd temperatureIncreases in temperature will denature enzymes as they are proteinsWhich 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 downDecrease in temperature decreases kinetic energy & lead to less possible contact

between proteins & enzymesThus fewer amino acids being produced/reduced enzyme activityAltering pH will also change the shape of the active siteLeading to fewer amino acids being produced/reduced enzyme activitySignificant increases or decreases in pH will stop all enzyme activity