IB Biology HL A2.2 Cell Structure Questions

Practise IB Biology HL A2.2 with micrograph and data questions on cell theory, microscopy, organelles, endosymbiosis, differentiation and structure–function evidence.

Exam points

State that organisms are composed of cells and that cells are the basic units of life, using pre-existing-cell evidence where assessed.
Calculate magnification or actual cell size, calibrate eyepiece graticules and outline safe focusing for light microscopy.
Compare light and electron microscopy and identify cryogenic or fluorescent techniques from resolution, preparation and imaging purpose.
Compare prokaryotic and eukaryotic cells, then label prokaryotic structures and link plasmids, pili, flagella or ribosomes to function.
Relate eukaryotic organelle compartmentalization and plant, animal or fungal structures to respiration, photosynthesis, transport, protein processing or cell support.
Explain how unicellular organisms carry out nutrition, response, homeostasis, growth and reproduction in one cell.
Explain how atypical multinucleate or anucleate cells challenge simple cell-theory expectations and identify cells or organelles in micrographs using structural evidence.
Evaluate endosymbiosis using engulfment and organelle–prokaryote similarities such as circular DNA, 70S ribosomes and double membranes.
Link selective gene expression in same-genome cells to different proteomes and specialised cell function.

Covered syllabus points

A2.2.1—Cells as basic structural unit A2.2.2—Microscopy skills A2.2.3—Developments in microscopy A2.2.4—Structures common to all cells A2.2.5—Prokaryote cell structure A2.2.6—Eukaryote cell structure A2.2.7—Processes of life in unicellular organisms A2.2.8—Differences in eukaryotic cells A2.2.9—Atypical cell structure A2.2.10—Cell identification in micrographs A2.2.11—Drawing and annotation A2.2.12 (HL)—Endosymbiosis origin of eukaryotes A2.2.13 (HL)—Cell differentiation A2.2.14 (HL)—Evolution of multicellularity

[Maximum number: 4]

(a)

Outline the cell theory.

[ 2 ]

(b)

Annotate the electron micrograph of the Escherichia coli cell with the function of the indicated structure.

[ 1 ]

(c)

Calculate the magnification of the electron micrograph.

[ 1 ]

$\quad \times 15000$

[Maximum number: 1]

The images of the radiolarian, a single-celled marine organism, were produced using a light microscope (left) and a scanning electron microscope (right).

What is a reason for the difference in quality of these images?

Light cannot pass through the specimen.

Higher magnification can be achieved with the electron microscope.

The resolution of the electron microscope is higher.

Samples are stained with methylene blue when viewed with the light microscope.

[Maximum number: 1]

The image shows a phagocytic white blood cell as seen with a transmission electron microscope.

Transmission electron micrograph of a phagocytic white blood cell, showing an irregular outer outline, a large indented nucleus and numerous small rounded structures in the surrounding cytoplasm.

Which features can be found both within this cell and in a photosynthetic bacterium?

Chloroplasts

Multiple nuclei

70S ribosomes

Lysosomes

[Maximum number: 2]

Outline the cell theory.

[Maximum number: 1]

Calculate the magnification of the electron micrograph.

$\quad \times 15000$

[Maximum number: 4]

Draw a labelled diagram of a prokaryotic cell.

[Maximum number: 1]

What cell component is found in eukaryotic cells but not in prokaryotic cells?

Mitochondria for respiration

DNA containing genetic information

Ribosomes for protein synthesis

Cell wall to maintain shape

[Maximum number: 3]

Excretion is one of the functions of life.

Compare and contrast excretion in humans and unicellular organisms such as Paramecium.

Similarities:

a. both expel $\mathrm{CO}_{2}$ /toxins/nitrogenous waste/waste products of metabolism;

Differences:

b. Paramecium does not have special organs for excretion OR

humans do have (special) organs/kidneys/lungs/skin/liver for excretion;

c. unicells/Paramecium excrete through their plasma membrane;

d. (entirely) passive/by diffusion in unicells/Paramecium but humans use energy/active transport (to move blood/air/solutes);

e. humans excrete urea whereas Paramecium excretes ammonia;

Marking guidance:

Reject answers stating that Paramecium excretes waste products by exocytosis.

[Maximum number: 3]

Eukaryotes are a diverse group of organisms, including animals and plants.

Distinguish between structures in animal and plant cells.

[Maximum number: 1]

The diagram shows the bones and muscles of the human elbow joint.

State one reason that striated muscle cells are considered atypical.

[Maximum number: 1]

(a) The image shows a cell in a section of an onion root tip seen under a light microscope.

Identify the structure labelled X .

[Maximum number: 4]

Cell biologists play an important role in research into disease, fertility, evolution and many other areas of science.

Describe the origin of eukaryotic cells according to the endosymbiotic theory.

[Maximum number: 1]

The micrograph shows two types of blood cell.

What determines the differences between the two types of cell?

Different number of mitotic cycles

Different expression of some genes

Reaction to oxygen of red blood cells

Reaction to antigens of white blood cells

All question bank results loaded

Covered syllabus points

Question 1

Question (a)

Question (b)

Question (c)

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13