Cells, Membranes & Exchange — Chapter quiz · Life Science: Biology, Grade 10

Connect cell structures, membrane transport, and exchange with the needs of cells.

Problem 1

Which scientist first used the word 'cells' after viewing thin slices of cork under a microscope?
  1. Antonie van Leeuwenhoek
  2. Theodor Schwann
  3. Rudolf Virchow
  4. Robert Hooke
Answer and explanation

Robert Hooke

Robert Hooke named the empty boxes he saw in cork 'cells' in 1665.

Problem 2

Rudolf Virchow's key addition to cell theory was the idea that
  1. all cells arise from pre-existing cells
  2. cells can form spontaneously from non-living matter
  3. only plants are made of cells
  4. cells are too small to ever be seen
Answer and explanation

all cells arise from pre-existing cells

Virchow's principle — every cell from a cell — completed cell theory and disproved spontaneous generation.

Problem 3

A microscope has a 10× eyepiece and a 100× objective lens. What is the total magnification?
Answer and explanation

1000 ×

Total magnification = eyepiece × objective = 10 × 100 = 1000×.

Problem 4

Which feature do prokaryotic cells lack that eukaryotic cells always have?
  1. DNA
  2. A membrane-bound nucleus
  3. Ribosomes
  4. A cell membrane
Answer and explanation

A membrane-bound nucleus

Prokaryotes have DNA, ribosomes, and a membrane, but no membrane-bound nucleus — the defining eukaryotic feature.

Problem 5

Which organelle reads the cell's instructions and builds proteins?
  1. Golgi apparatus
  2. Nucleus
  3. Ribosome
  4. Mitochondrion
Answer and explanation

Ribosome

Ribosomes assemble proteins by linking amino acids in the order the DNA specifies.

Problem 6

Which organelle carries out cellular respiration, releasing energy from food as ATP?
  1. Ribosome
  2. Endoplasmic reticulum
  3. Nucleus
  4. Mitochondrion
Answer and explanation

Mitochondrion

The mitochondrion is the cell's powerhouse, releasing usable energy (ATP) through cellular respiration.

Problem 7

In a phospholipid, the phosphate head is hydrophilic and the fatty-acid tails are
  1. hydrophobic
  2. hydrophilic
  3. charged
  4. made of protein
Answer and explanation

hydrophobic

The tails are hydrophobic (water-fearing), which is why they hide in the middle of the bilayer, away from water.

Problem 8

Explain why oxygen can cross the cell membrane directly but a charged ion cannot.
Answer and explanation

The inside of the phospholipid bilayer is a hydrophobic, oily core. Oxygen is a small nonpolar molecule, so it dissolves through that core easily. A charged ion is repelled by the hydrophobic core, so it can't cross the lipid directly and must pass through a transport (channel) protein instead.

Problem 9

An animal cell is placed in a hypertonic solution. What happens?
  1. The cell grows a cell wall
  2. Water leaves the cell by osmosis and the cell shrivels
  3. Water enters and the cell swells and bursts
  4. Nothing, because hypertonic means equal solute
Answer and explanation

Water leaves the cell by osmosis and the cell shrivels

Hypertonic means more solute outside, so water leaves the cell by osmosis and the cell shrivels (crenates).

Problem 10

Which statement about active transport is correct?
  1. It only moves water
  2. It never involves proteins
  3. It uses energy (ATP) to move substances against their concentration gradient
  4. It moves substances down their gradient with no energy
Answer and explanation

It uses energy (ATP) to move substances against their concentration gradient

Active transport spends energy to pump substances from low to high concentration, against the gradient.

Problem 11

The claim "the cell is the basic unit of structure and function in living things" is best supported by the observation that
  1. cells are always visible to the unaided eye
  2. the smallest things that carry out all life processes independently are single cells
  3. all cells are identical in shape
  4. cells never divide
Answer and explanation

the smallest things that carry out all life processes independently are single cells

A single cell can perform every life process, while no smaller part of it can do so independently, which is what makes the cell the basic functional unit.

Problem 12

Viruses contain genetic material and reproduce, yet cell theory is not usually revised to include them. Explain the reasoning on both sides.
Answer and explanation

Viruses are not cells: they have no cytoplasm, no ribosomes, and no metabolism of their own, and they replicate only by directing a host cell's machinery. Because they cannot carry out life processes independently, most biologists treat them as outside the theory's scope rather than as a counterexample. The argument on the other side is that they possess heritable information and evolve, which are properties of living things, so the boundary the theory draws is a definitional choice that the evidence does not settle by itself.

Response criteria

  • State a biologically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 13

Independent chapter check: A cell spans 2.4 lengths of a 25 μm scale bar. Find its estimated length and explain why a resized “400×” label is less useful than the correctly resized bar.
Answer and explanation

The estimate is 2.4×25 = 60 μm. A magnification label describes a particular display enlargement; resizing changes it, while an image and scale bar resized together preserve the specimen-length ratio.

The estimate is 2.4×25 = 60 μm. A magnification label describes a particular display enlargement; resizing changes it, while an image and scale bar resized together preserve the specimen-length ratio.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the biological mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 14

Both a bacterium and a human cell make proteins. The structure they share that makes this possible is the
  1. nucleus
  2. ribosome
  3. mitochondrion
  4. Golgi apparatus
Answer and explanation

ribosome

Ribosomes assemble proteins and are present in all cells. The other three structures are absent from prokaryotes.

Problem 15

Explain why compartments give a eukaryotic cell capabilities a prokaryotic cell lacks, and name one cost of that organization.
Answer and explanation

Membrane-bound compartments let incompatible conditions exist at once in one cell: digestive enzymes can be concentrated inside a lysosome at low pH without damaging the cytoplasm, and reactions can be localized so their intermediates stay concentrated. That supports larger cells and more specialized functions. The cost is overhead: materials must be transported and sorted between compartments, which requires membrane, vesicles, targeting signals, and energy that a prokaryote does not spend.

Response criteria

  • State a biologically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 16

Independent chapter check: A cell makes a protein that will be exported. Explain the roles of DNA/RNA information, rough ER, Golgi and vesicles, and why this route need not describe a cytosolic enzyme.
Answer and explanation

Gene information is transcribed and used by ribosomes; selected secretory proteins enter the ER, undergo processing/sorting through Golgi and travel in vesicles to membrane fusion. A cytosolic enzyme generally follows a different localization pathway rather than compulsory secretion.

Gene information is transcribed and used by ribosomes; selected secretory proteins enter the ER, undergo processing/sorting through Golgi and travel in vesicles to membrane fusion. A cytosolic enzyme generally follows a different localization pathway rather than compulsory secretion.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the biological mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 17

Cholesterol inserted among the phospholipids of an animal cell membrane mainly affects the membrane's
  1. genetic content
  2. fluidity and stability
  3. ribosome count
  4. ability to synthesize protein
Answer and explanation

fluidity and stability

Cholesterol packs between phospholipids and moderates fluidity, keeping the membrane stable across a range of temperatures.

Problem 18

Explain why a cell membrane could not be made of a single layer of phospholipids in a watery environment, using polarity.
Answer and explanation

Each phospholipid has a polar head and nonpolar tails. In water, a single layer would leave one face's tails exposed to water on one side, which water excludes. A bilayer resolves this by turning all tails inward toward each other and all heads outward toward the water on both sides, so no nonpolar surface contacts water. The structure is a consequence of polarity, not an arbitrary arrangement.

Response criteria

  • State a biologically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 19

Independent chapter check: A small charged solute crosses a cell membrane only after a matching channel opens. Explain why size alone and the phrase “fluid membrane” do not predict its passage.
Answer and explanation

Charge and lipid-interior interactions limit the direct route; the selective channel changes the available pathway. Fluidity concerns component motion, not unrestricted permeability to every substance.

Charge and lipid-interior interactions limit the direct route; the selective channel changes the available pathway. Fluidity concerns component motion, not unrestricted permeability to every substance.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the biological mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 20

Which process requires no energy input from the cell?
  1. Pumping sodium out against its gradient
  2. Taking in a large particle by endocytosis
  3. Oxygen diffusing into a cell down its gradient
  4. Concentrating potassium above the external level
Answer and explanation

Oxygen diffusing into a cell down its gradient

Movement down a gradient is passive. The other three move material against a gradient or require membrane reorganization, both of which consume energy.

Problem 21

A cell's glucose uptake rises as external glucose rises, then levels off even though more glucose is available. Explain the result and say how you would test your explanation.
Answer and explanation

Glucose enters through carrier proteins. As external glucose rises, more carriers are occupied and uptake rises; once essentially all carriers are working continuously, the carriers are saturated and uptake cannot rise further, so the curve plateaus. The explanation predicts that increasing the number of carriers — for example in a cell induced to make more — raises the plateau, while adding more glucose does not. Measuring uptake in cells with high and low carrier counts at the same external concentration would test it.

Response criteria

  • State a biologically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 22

Independent chapter check: A tissue sample changes from 12 g to 9 g in a stated nonpenetrating-solute model. Find percentage change and explain a suitable osmotic account plus one measurement control.
Answer and explanation

The change is −3/12×100 = −25%. Net water loss is consistent with a hypertonic external solution under the model. Comparable blotting, membrane integrity and limits on solute loss are needed before assigning all mass change to water.

The change is −3/12×100 = −25%. Net water loss is consistent with a hypertonic external solution under the model. Comparable blotting, membrane integrity and limits on solute loss are needed before assigning all mass change to water.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the biological mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 23

Find area/volume for a cube with side length 6 mm.
Answer and explanation

1 mm⁻¹

6/6 = 1.

Problem 24

Why does a cube’s area/volume ratio not give the actual oxygen-transfer rate?
Answer and explanation

Permeability, concentration gradient, distance, demand, and transport conditions also affect exchange.

Problem 25

Independent chapter check: A cube’s side length rises from 2 to 4 mm. Calculate area, volume and area/volume for both, then explain why “the larger one has less surface” is misleading.
Answer and explanation

At 2 mm: area 24 mm², volume 8 mm³, ratio 3 mm⁻¹. At 4 mm: area 96 mm², volume 64 mm³, ratio 1.5 mm⁻¹. Total surface increases while area per volume falls; actual exchange also depends on pathways and demand.

At 2 mm: area 24 mm², volume 8 mm³, ratio 3 mm⁻¹. At 4 mm: area 96 mm², volume 64 mm³, ratio 1.5 mm⁻¹. Total surface increases while area per volume falls; actual exchange also depends on pathways and demand.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the biological mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Browse all courses