Question

what is the role of the nucleolus found within the nucleus?
a. it provides energy to the nucleus.
b. it stores the cells dna.
c. it is where ribosomes are partially assembled.
d. it controls the movement of substances in and out of the nucleus.

what structural feature of the cell membrane allows it to be selectively permeable?
a. the double helix structure of dna.
b. the presence of channels and pores.
c. the fluid inside the nucleus.
d. its rigid outer layer.

Explanation:

• First question:
• Option a: Mitochondria (not the nucleolus) provide energy (ATP) to the cell.
• Option b: DNA is stored in the nucleus (not specifically in the nucleolus).
• Option c: The nucleolus is involved in ribosome biogenesis, specifically in partially assembling ribosomal subunits.
• Option d: The nuclear membrane (with nuclear pores) controls the movement of substances in and out of the nucleus.
• Second question:
• Option a: The double - helix structure of DNA is related to genetic information storage, not cell membrane permeability.
• Option b: The presence of channels (e.g., ion channels) and pores (e.g., aquaporins) in the cell membrane allows it to be selectively permeable, controlling what enters and exits the cell.
• Option c: The fluid inside the nucleus (nucleoplasm) has no direct relation to cell membrane permeability.
• Option d: A rigid outer layer (like a cell wall in plant cells) is not a feature of the cell membrane's selective permeability mechanism.

Answer:

• First question: C. It is where ribosomes are partially assembled.
• Second question: B. The presence of channels and pores.