Biology Test Biology Cell Structure & Function 4

Question 1

Which of the following organelles contains its own DNA and ribosomes, supporting the endosymbiotic theory?

Accepted Answer

Mitochondria and chloroplasts

Answer

Mitochondria and chloroplasts possess circular DNA and 70S ribosomes similar to prokaryotes, supporting the idea they evolved from ancient endosymbiotic bacteria.

Question 2

What is the function of the nucleolus within the nucleus?

Accepted Answer

Synthesizing ribosomal RNA and assembling ribosome subunits

Answer

The nucleolus is a dense region within the nucleus where rRNA genes are transcribed and ribosomal subunits are assembled before export to the cytoplasm.

Question 3

How do nuclear pores regulate traffic between the nucleus and cytoplasm?

Accepted Answer

They use FG-nucleoporins to selectively allow proteins and RNA to pass

Answer

Nuclear pore complexes contain FG-repeat nucleoporins that create a selective barrier, allowing small molecules to diffuse freely while large proteins and RNA require importin/exportin receptors.

Question 4

In a secretory cell like a pancreatic acinar cell, what is the correct order of organelles a newly synthesized digestive enzyme passes through before secretion?

Accepted Answer

Rough ER → Golgi → Secretory vesicle → Plasma membrane

Answer

Secretory proteins are synthesized on rough ER ribosomes, processed in the ER lumen, transported to the Golgi for modification, packaged into secretory vesicles, and released by exocytosis.

Question 5

Peroxisomes differ from lysosomes in that peroxisomes:

Accepted Answer

Use hydrogen peroxide as an oxidative tool to detoxify substances

Answer

Peroxisomes use oxidative reactions (often generating and then neutralizing H₂O₂) to break down fatty acids and detoxify alcohol, while lysosomes use acid hydrolases.

Biology Practice Test

Biology Practice Test

Biology Test Biology Cell Structure & Function 4