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Biology Exam Essay Questions

Step-by-Step Biology Learning

Based on theory of knowledge and brain science, Biology Q&As was specifically designed, written and organized to make learning biology easier. More than 1800 bite-sized Q&As, covering all of the primary branches and subjects in biology, are available to make studying biology as easy for you as possible.

By following  the logical sequence of questions for each subject, from basic concepts to more advanced ones, you will learn more than ever. Discover how to build your knowledge of biology step by step, through intelligent sequences of Q&As.

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135 logically organized Q&As, starting with the basic concepts and moving on to water properties and mineral salts, carbohydrates, lipids, proteins, enzymes, and nucleic acids.

Cell Biology

Review cell biology through 204 Q&As designed to make learning biology’s main subjects, such as cell structure, cell division, photosynthesis, and protein synthesis, easier.


Familiarize yourself with bacteria, protists, viruses, and fungi with 59 Q&As spanning the basic concepts to more advanced ones.


242 Q&As can be found here covering the main phyla: poriferans, cnidarians, flatworms, roundworms, annelids, arthropods, molluscs, echinoderms, and chordates. 


Discover how easy it is to study and understand everything about physiology by using these logical sequences of 506 Q&As.


Learn everything you need to know at the high school level about embryonic development and extraembryonic membranes through just 40 Q&As.


From plant classification to plant physiology, we cover the main subjects of botany with 141 Q&As written by biology teachers.


These 139 Q&As are tailored to help you review fundamental concepts as well as Mendel's laws, non-Mendelian inheritance, linkage, and more.


Discover known facts and hypotheses on the origin of life and the theory of evolution by reviewing these 50 Q&As.


Imagine learning ecology through just 140 Q&As structured to teach you about ecosystems, biomes, food chains, biodiversity, ecological interactions, ecological succession, population, and environmental issues.


Do you know the difference between atherosclerosis and arteriosclerosis? You will, plus so much more on common diseases, when you review these 131 Q&As.

Previous IB Exam Essay Questions: Unit 1

Use these model essay question responses to prepare for essay questions on your in class tests, as well as the IB Examination, Paper 2. These questions have appeared on recent IB examinations, exactly as shown below. Following each question is the markscheme answer which was used to evaluate student answers on the examination paper.
1. Discuss possible exceptions to cell theory.4 marks
  • skeletal muscle fibers are larger/have many nuclei/are not typical cells
  • fungal hyphae are (sometimes) not divided up into individual cells
  • unicellular organisms can be considered acellular
  • because they are larger than a typical cell/carry out all functions of life
  • some tissues/organs contain large amounts of extracellular material
  • e.g. vitreous humor of eye/ mineral deposits in bone/ xylem in trees/other example
  • statement of cell theory/all living things/most tissues are composed entirely of true cells

2. Eukaryotic cells have intracellular and extracellular components. State the functions of one named extracellular component.4 marks

name of component: 1 max

  • e.g. plant cell wall/cellulose/interstitial
  • matrix/basement membrane/glycoprotein/bone matrix;
functions: 3 max


  • e.g. (plant cell wall) strengthens/supports the cell/plant (against gravity);
  • prevents the entry of pathogens;
  • maintains the shape of plant cells;
  • allows turgor pressure/high pressure to develop inside the cell;
  • prevents excessive entry of water to the cell;
  • helps cells to stick together/adhere;
  • needed to hold cells/tissues together / example of cells/tissues holding together;
  • forms interstitial matrix / forms basement membrane to support single layers of cells;
  • e.g. around a blood capillary;
  • forms (part of the) filtration membrane in the glomerulus;

3. Explain how the surface are to volume ratio influences cell sizes.3 marks

  • small cells have larger ratio (than larger cells)/ratio decreases as size increases
  • surface area/membrane must be large enough to absorb nutrients/oxygen/substances needed
  • surface area/membrane must be large enough to excrete/pass out waste products
  • need for materials is determined by (cell) volume
  • cell size is limited (by SA/Volume ratio)/cells divide when they reach a certain size
  • reference to diffusion across/through membrane/surface area

4. Outline differentiation of cells in a multicellular organism.4 marks

  • differentiation is development in different/specific ways
  • cells carry out specialized functions/become specialized
  • example of a differentiated cell in a multicelluar organism
  • cells have all genes/could develop in any way
  • some genes are switched on/expressed but not others
  • position/hormones/cell-to-cell signals/chemicals determine how a cell develops
  • a group of differentiated cells is a tissue

5. Describe the importance of stem cells in differentiation.3 marks

  • stem cells are undifferentiated cells;
  • embryo cells are stem cells;
  • stem cells can differentiate in many/all ways / are pluripotent/totipotent;
  • differentiation involves expressing some genes but not others;
  • stem cells can be used to repair/replace tissues/heal wounds;

6. Draw a labelled diagram to show the ultrastructure of Escherichia coli.6 marks

Award 1 for each structure clearly drawn and correctly labelled.

  • cell wall – with some thickness;
  • plasma membrane – shown as single line or very thin;
  • cytoplasm;
  • pilus/pili – shown as single lines;
  • flagellum/flagella – shown as thicker and longer structures than pili and embedded in cell wall;
  • 70S ribosomes;
  • nucleoid / naked DNA;
  • approximate width 0.5 μm / approximate length 2.0 μm;
Award 4 max if the bacterium drawn does not have the shape of a bacillum (rounded-corner rectangle with length approximately twice its width).Award 4 max if any eukaryotic structures included.

7. Draw a labelled diagram to show the organelles which are found in the cytoplasm of plant cells.6 marks

Award 1 mark for each of the following structures accurately drawn and labelled

  • rough endoplasmic reticulum
  • free ribosomes
  • Golgi apparatus
  • mitochondrion
  • chloroplast
  • vacuole
  • nucleus
  • lysosome
  • smooth endoplasmic reticulum

8. State one function of each of the following organelles: lysosome, Golgi apparatus, rough endoplasmic reticulum, nucleus, mitochondrion.5 marks

  • lysosome: hydrolysis/digestion/break down of materials (macromolecules)
  • Golgi apparatus: synthesis/sorting/transporting/secretion of cell products
  • rough endoplasmic reticulum: site of synthesis of proteins (to be secreted)/ intracellular transport of polypeptides to Golgi apparatus
  • nucleus: controls cells activities/mitosis/replication of DNA/transcription of DNA (to RNA)/directs protein synthesis
  • mitochondrion: (aerobic) respiration/generates ATP

9. Draw a labelled diagram showing the ultra-structure of a liver cell.4 marks

Award 1 for each structure clearly drawn and correctly labelled. Whole cells not necessary.

  • (plasma) membrane – single line surrounding cytoplasm;
  • nucleus – with a double membrane and pore(s) shown;
  • mitochondria(ion) – with a double membrane, the inner one folded into internal
  • projections, shown no larger than half the nucleus;
  • rough endoplasmic reticulum – multi-folded membrane with dots/small circles on surface;
  • Golgi apparatus – shown as a series of enclosed sacs with evidence of vesicle formation;
  • ribosomes – dots/small circles in cytoplasm/ribosomes on rER;
  • lysosome;
Award 0 if plant cell is drawn. Award 2 max if any plant cell structure (e.g. cell wall) is present.

10. Distinguish between the structure of plant and animal cells.6 marks

Award 1 mark per differenceplant cells

  • have cell walls, animals do not
  • have plastids/ chloroplasts, animals do not
  • have a large central vacuole, animals do not
  • store starch, animal cells store glycogen
  • have plasmodesmata, animal cells do not

animal cells

  • have centrioles, plant cells do not
  • have cholesterol in the cell membrane, plant cells do not
  • plant cells are generally have a fixed shape/ more regular whereas animal cells are more rounded

11. Using a table, compare the structures of prokaryotic and eukaryotic cells.5 marks

P: prokaryotic cells; E: eukaryotic cells

  • DNA: P: naked/loop of DNA; E: associated with protein/histones/nucleosomes/DNA in chromosomes
  • location of DNA: P: in cytoplasm/nuceloid/no nucleus; E: within a nucleus/nuclear membrane
  • membrane bound organelles: P: none; E: present
  • ribosomes: P: 70S ; E: 80S
  • plasma membrane: P & E: same structure within both groups
  • cell wall: P: peptidoglycan/not cellulose/not chitin; E: cellusose/chitin/not peptidoglycan
  • respiratory structures: P: no mitochondria; E: mitochondria
  • pili: P: pili present E: pili absent;
  • plasmids: P: plasmids (sometimes) present E:plasmids absent;
  • flagella: P: flagella solid E: flagella flexible/membrane-bound;

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