Daily Olympiad: Biology - Cell Structure Function [20260511] – 7 Practice Problems & Printable PDF

1. Which of the following cell wall layers in plant cells is responsible for providing maximum mechanical strength?

A. Primary wall B. Secondary wall C. Middle lamella D. Cuticle

Solution

Correct: B

The secondary cell wall, deposited after the primary wall, is heavily lignified and provides the greatest mechanical strength to plant cells. The primary wall is flexible, middle lamella acts as a glue, and cuticle prevents water loss.

2. Which organelle is directly involved in the synthesis of sphingolipids, a component of myelin sheathes in nerve cells?

A. Rough endoplasmic reticulum B. Golgi apparatus C. Smooth endoplasmic reticulum D. Lysosome

Solution

Correct: C

Sphingolipid synthesis occurs in the smooth endoplasmic reticulum. The rough ER is involved in protein synthesis, Golgi in modification, and lysosomes in degradation. Schwann cells use smooth ER to synthesize these lipids for myelin formation.

3. In which type of eukaryotic cell would you expect the highest number of lysosomes?

A. Muscle cells B. Neurons C. Leukocytes (white blood cells) D. Epithelial cells

Solution

Correct: C

Leukocytes (white blood cells) have abundant lysosomes because they play a critical role in phagocytosing pathogens. Lysosomes digest the ingested material, making this cell type specialized for such activity.

4. The cristae of mitochondria are significantly more numerous in cardiac muscle cells compared to skin cells. This is primarily due to:

A. Higher rates of protein synthesis B. Increased demand for ATP C. Need for more calcium ion storage D. Requirement for lipid breakdown

Solution

Correct: B

Cardiac muscle cells require sustained energy production. Increased cristae maximize inner mitochondrial membrane surface area for more ATP production via oxidative phosphorylation, which meets their high metabolic demand.

5. Which of the following statements about the nucleolus is correct?

A. It contains DNA but no RNA B. It is membrane-bound C. It is the site of ribosome biogenesis D. It synthesizes tRNA for nucleoplast use

Solution

Correct: C

The nucleolus is the site where ribosomal RNA (rRNA) is transcribed and assembled with proteins to form ribosome subunits. It is not membrane-bound and lacks DNA in most eukaryotes.

6. Cilia and flagella of eukaryotic cells differ from bacterial flagella in that:

A. They are composed of flagellin protein B. They use ATP for movement C. They have a 9+2 microtubule structure D. They are longer

Solution

Correct: C

Eukaryotic cilia and flagella have a 9+2 arrangement of microtubules and use ATP powered by dynein motors. Bacterial flagella are single filament proteins without microtubules and have a different rotation mechanism.

7. Which component of the cell membrane is most responsible for maintaining membrane stability in cells exposed to high osmotic stress?

A. Cholesterol B. Phosphatidylserine C. Integral proteins D. Glycolipids

Solution

Correct: A

Cholesterol modulates membrane fluidity by preventing excessive fluidity at high temperatures and preventing rigidification at low temperatures. It acts as a buffer to stabilize the lipid bilayer under osmotic stress.