Preliminary Biology Exam 2021

55 marks – 1 and half hours

Questions

Question 1.

Compare and contrast animal and plant cell organelles. [4 marks]

Question 2.

Compare and contrast prokaryotes and eukaryotes. [4 marks]

Question 3.

Evaluate the use of models in science. [6 marks]

Question 4.

Explain the evidence for evolution for an animal or plant of your choosing [4 marks]

Question 5.

Evaluate the SA:V ratio used by the respiratory, digestive and circulatory system in the human body [7 marks]

Question 6.

A keen biology student makes two observations

  • i) The dolphin and shark both share similar fin configurations
  • ii) The pentadactyl limb of humans and horses appear to have common bones

‘These are both examples of divergent evolution’

Assess the validity of the students conclusion [5 marks]

Question 7.

During the current outbreak of Covid 19, there have been multiple strains of the virus we have seen emerge. Explain using the theory of natural selection, why the strains appear to be more infectious. [5 mark]

Open ended and after original thought and linking together concepts learnt throughout the course.

Question 8.

Compare and contrast gradualism and punctuated equilibrium. [4 marks]

Question 9.

Evaluate the effectiveness of managing land through the introduction of non-native species [6 marks]

Question 10.

Explain how the digestive system optimizes function for various enzymes. [4 marks]

Question 11.

  1. What is the cell membrane made of [1 mark]
  2. Explain the fluid mosaic model and its importance to transport [3 marks]

Question 12.

When red blood cells are placed in: 

  • solution A, the red blood cells explode
  • Solution B, the red blood cells shrivel up
  • Solution C, the red blood cells don’t change

Rank the three solutions from most concentrated to least concentrated. [3 marks]

Answers.

Question 1.

Compare and contrast animal and plant cell organelles. [4 marks]

ReasonMark
Any two of the following for similaritiesThey both contain a nucleus which holds the cells genetic instruction, therefore, they are both eukaryoticBoth plant and animal cells contain mitochondria which allow for the creation of ATP, therefore, allowing for function of other organelles2
Any two of the following for differencesOnly plant cells have a cell wall because they don’t have a skeletal systemChloroplasts → Animal cells have a much smaller vacuole because to allow the cells to be more mobile as animals cells are not self sufficient and are consumers. 2

Question 2.

Compare and contrast prokaryotes and eukaryotes. [4 marks]

Prokaryotes are bacteria

Eukaryotes are plant, animal, fungi, algae

ReasonMark
SimilaritiesBoth contain ribosomesBoth contain genetic information, with universal code for proteinsBoth contain cytoplasm2
DifferencesProkaryotic contain no membrane bound organellesProkaryotes are often smaller and less complex2

Question 3.

Evaluate the use of models in science. [6 marks]

Scaffold:

  • Topic sentence – define ‘model’ & judge
  • 2-3 for and against models
  • Include examples
  • Allows for a more practical approach 
  • Draw a conclusive sentence

Question 4.

Explain the evidence for evolution for an animal or plant of your choosing [4 marks]

ReasonMark
Explains the change in environment1
Explains subsequent change in organism1
Mentions any of the following as evidenceBiochemistryEmbryologyBiogeographyAnatomy2

Question 5.

Evaluate the SA:V ratio used by the respiratory, digestive and circulatory system in the human body [7 marks]

ReasonMark
Links alveoli to increased SA:V ratio in lungsStates whether this is good or bad, evaluating it’s effectiveness at increasing exchange of gas2
Links microvilli to increased SA:V ratio in small intestineStates whether this is good or bad, evaluating its effectiveness at increasing uptake of nutrients2
Links capillaries to increased SA:V ratio in circulatory systemStates whether this is good or bad, evaluating its effectiveness at increasing exchange of nutrients, gas and waste between cells and blood2

Question 6.

A keen biology student makes two observations

  • i) The dolphin and shark both share similar fin configurations
  • ii) The pentadactyl limb of humans and horses appear to have common bones

‘These are both examples of divergent evolution’

Assess the validity of the students conclusion [5 marks]

Reason Mark
Assess the validity of the students statement – doesn’t say it is valid, can be invalid or partially valid1
DefinesConvergent (analogous structures) and divergent (homologous structures) evolution
ExampleDivergent evolution for the pentadactyl limbConvergent  evolution for the shark and dolphin fins2

Question 7.

During the current outbreak of Covid 19, there have been multiple strains of the virus we have seen emerge. Explain using the theory of natural selection, why the strains appear to be more infectious. [5 mark]

Open ended and after original thought and linking together concepts learnt throughout the course.

  • Open ended application style question –> marks for skill

Question 8.

Compare and contrast gradualism and punctuated equilibrium. [4 marks]

ReasonMarks
2 ways they differ e.gShort periods of time of rapid change and times of no change (static) for punctuated equilibrium vs long gradual slow accumulative changes for Link to difference in changes of selective pressure2
2 ways they are similar e.gBoth a way of evolving to changes in the environmentBoth examples of Neo Darwinism2

Question 9.

Evaluate the effectiveness of managing land through the introduction of non-native species [6 marks]

ReasonMark
Provides an insightful evaluation, specifying how what they have evaluated can be better used2 marks
Provides at least 2 points for and/or against2 marks
Uses examples in answerPrickly pairCane toad2 marks

Question 10.

Explain how the digestive system optimizes function for various enzymes. [4 marks]

ReasonMark
Provides at least 2 reasons for how the body optimizes function of enzyme – constant temp and varied pH 2 marks
Provides example for the 2 reasons providedAll enzymes in body optimized for human body tempPepsin activated by acidic stomach pHGastric lipase optimized for function in low pHSalivary amylase optimized for more neutral pH for the mouth 2 marks

Question 11.

  1. What is the cell membrane made of [1 mark]
  2. Explain the fluid mosaic model and its importance to transport [3 marks]

Answer

  1. Phospholipid
Reasonmark
Allows for the movement of the cell since nothing is fixed in place1
Allows for exchange of gas and water molecules through the phospholipid bilayer1
Charged molecules and molecules cannot pass through without carrier proteins assisting1

Question 12.

When red blood cells are placed in: 

  • solution A, the red blood cells explode
  • Solution B, the red blood cells shrivel up
  • Solution C, the red blood cells don’t change

Rank the three solutions from most concentrated to least concentrated. [3 marks]

ReasonMark
Correct order B, C, A3

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