Prokaryotic & Eukaryotic Cells & Their Organelles — Practice · Grade 10 Science

Chapter: Cells, Membranes & Exchange

What this practice covers

By the end of Prokaryotic & Eukaryotic Cells & Their Organelles you should be able to:

11 questions, multiple choice, written answer and numeric, each with a worked explanation.

Vocabulary used: prokaryote, eukaryote, organelle, nucleus, ribosome, endoplasmic reticulum, Golgi apparatus, mitochondrion.

Problem 1

Which feature is found in eukaryotic cells but NEVER in prokaryotic cells?
  1. A cell membrane
  2. Ribosomes
  3. A membrane-bound nucleus
  4. DNA
Answer and explanation

A membrane-bound nucleus

Prokaryotes have DNA, ribosomes, and a cell membrane, but they lack a true membrane-bound nucleus — that is the defining eukaryotic feature.

Problem 2

Which organelle modifies, sorts, and packages proteins into vesicles for shipping?
  1. Mitochondrion
  2. Ribosome
  3. Nucleus
  4. Golgi apparatus
Answer and explanation

Golgi apparatus

The Golgi apparatus is the cell's shipping department, tagging and packaging proteins into vesicles addressed to their destinations.

Problem 3

Why is the rough endoplasmic reticulum described as 'rough'?
  1. It is studded with ribosomes that build and process proteins
  2. It has a jagged outer wall
  3. It stores rough, undigested food
  4. It contains chloroplasts
Answer and explanation

It is studded with ribosomes that build and process proteins

Ribosomes attached to its surface give the rough ER its bumpy look and its role in processing newly made proteins.

Problem 4

State two pieces of evidence that support the endosymbiotic origin of mitochondria.
Answer and explanation

Mitochondria have their own circular DNA separate from the nucleus, they are wrapped in a double membrane, and they divide on their own schedule — all clues that they descend from free-living bacteria engulfed by an ancestral cell.

Problem 5

A typical eukaryotic cell is about 40 micrometers across, while a typical bacterium is about 2 micrometers across. How many times wider is the eukaryotic cell?
Answer and explanation

20 ×

40 ÷ 2 = 20 times wider, reflecting the much larger size of eukaryotic cells.

Problem 6

Some antibiotics kill bacteria by jamming their ribosomes yet leave human cells unharmed. The best explanation is that
  1. bacteria have no ribosomes to jam
  2. bacterial (prokaryotic) ribosomes differ enough from human (eukaryotic) ribosomes for the drug to target one and not the other
  3. human cells have no ribosomes
  4. antibiotics cannot enter human cells at all
Answer and explanation

bacterial (prokaryotic) ribosomes differ enough from human (eukaryotic) ribosomes for the drug to target one and not the other

Prokaryotic ribosomes are structurally different from eukaryotic ones, so a drug can disable bacterial ribosomes while sparing our own — a key principle of selective antibiotics.

Problem 7

Trace a protein secreted by a typical eukaryotic cell through major compartments. Explain the reasoning in your own words.
Answer and explanation

Ribosome→rough ER→Golgi→secretory vesicle→cell exterior, in a simplified pathway.

Ribosomes associated with rough ER synthesize the protein into the secretory pathway.

It passes through ER and Golgi processing and vesicles to the cell surface.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 8

A cell contains a nucleus and mitochondria. Which broad category fits? Show the reasoning, not just the conclusion.
Hints

Ribosomes alone do not distinguish these types.

Answer and explanation

Eukaryotic; these membrane-bound structures support that classification.

Problem 9

Would every cell in a plant contain chloroplasts? Explain.
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

No. Chloroplast abundance depends on tissue and function; many root cells do not photosynthesize.

Problem 10

A secretion pathway connects information, synthesis and membranesA secretion pathway connects information, synthesis and membranesGeneRough ERGolgiVesicle → membraneA secreted protein is made, processed and carried through a pathway.
Original secretion-route model. Arrows summarize several distinct steps, and the small vesicle is not a literal protein molecule.
Interpret the supplied visual. Does the presence of Golgi prove that every protein in the cell is secreted?
Answer and explanation

No. It handles selected cargo; many proteins remain in other compartments and use different targeting routes.

The endoplasmic reticulum, ER, is a membrane network; ribosomes attached to rough ER can make proteins entering the secretory pathway. The Golgi apparatus modifies and sorts selected products. A vesicle is a membrane-bounded transport compartment, and exocytosis releases contents when its membrane fuses with the plasma membrane. The nucleus supplies transcribed information rather than shipping a finished protein through the whole route. Not all proteins follow this pathway; cytosolic proteins and organelle-targeted proteins have other destinations and targeting mechanisms.

No. It handles selected cargo; many proteins remain in other compartments and use different targeting routes.

Response criteria

  • Read the structures, axes, directions and units correctly.
  • Connect the evidence with the biological mechanism.
  • Respect stated model assumptions and distinguish an observation from a further inference.

Problem 11

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.

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