BIOS 255 Final Exam Questions and Correct
Answers (Verified Answers) Plus Rationale
2027 Q&A| Instant Download Pdf
1. Which statement best describes the primary function of the
plasma membrane?
A. It stores the cell's genetic material
B. It synthesizes proteins
C. It regulates movement of substances into and out of the cell
D. It produces ATP
Answer: C. It regulates movement of substances into and out of the
cell
Rationale: The plasma membrane is selectively permeable, allowing
certain substances to enter or leave the cell while restricting others. This
regulation helps maintain cellular homeostasis. DNA is primarily located
in the nucleus, proteins are synthesized by ribosomes, and most ATP is
produced by mitochondria.
, 2. Which organelle is primarily responsible for producing ATP
through aerobic cellular respiration?
A. Golgi apparatus
B. Mitochondrion
C. Lysosome
D. Nucleolus
Answer: B. Mitochondrion
Rationale: Mitochondria are the major sites of aerobic cellular
respiration and oxidative phosphorylation. They use energy from
nutrients to generate ATP, the cell's principal energy currency. The Golgi
modifies and packages proteins, lysosomes digest cellular materials,
and the nucleolus produces ribosomal components.
3. Which molecule carries genetic information from DNA to the
ribosome for protein synthesis?
A. tRNA
B. rRNA
C. mRNA
D. ATP
Answer: C. mRNA
,Rationale: Messenger RNA (mRNA) is transcribed from DNA and carries
the genetic instructions to ribosomes, where the sequence is translated
into a protein. Transfer RNA delivers amino acids, while ribosomal RNA
forms an important structural and catalytic component of ribosomes.
4. Which process produces two genetically identical daughter cells?
A. Meiosis
B. Binary fission
C. Mitosis
D. Crossing over
Answer: C. Mitosis
Rationale: Mitosis involves nuclear division that generally produces two
genetically similar daughter cells with the same chromosome number as
the parent cell. Meiosis produces genetically varied haploid cells, while
crossing over is a genetic recombination event during meiosis.
5. During which stage of the cell cycle is DNA replicated?
A. G₁ phase
B. S phase
C. G₂ phase
D. M phase
Answer: B. S phase
, Rationale: DNA synthesis occurs during the S, or synthesis, phase of
interphase. G₁ involves cell growth and normal cellular activities, G₂
prepares the cell for division, and M phase includes mitosis and
cytokinesis.
6. Which structure contains the cell's chromosomes in a typical
eukaryotic cell?
A. Ribosome
B. Lysosome
C. Nucleus
D. Centriole
Answer: C. Nucleus
Rationale: In eukaryotic cells, chromosomes are housed within the
membrane-bound nucleus. The nucleus protects and organizes DNA and
regulates gene expression. Prokaryotic cells lack a membrane-bound
nucleus.
7. What is the movement of water across a selectively permeable
membrane called?
A. Diffusion
B. Osmosis
Answers (Verified Answers) Plus Rationale
2027 Q&A| Instant Download Pdf
1. Which statement best describes the primary function of the
plasma membrane?
A. It stores the cell's genetic material
B. It synthesizes proteins
C. It regulates movement of substances into and out of the cell
D. It produces ATP
Answer: C. It regulates movement of substances into and out of the
cell
Rationale: The plasma membrane is selectively permeable, allowing
certain substances to enter or leave the cell while restricting others. This
regulation helps maintain cellular homeostasis. DNA is primarily located
in the nucleus, proteins are synthesized by ribosomes, and most ATP is
produced by mitochondria.
, 2. Which organelle is primarily responsible for producing ATP
through aerobic cellular respiration?
A. Golgi apparatus
B. Mitochondrion
C. Lysosome
D. Nucleolus
Answer: B. Mitochondrion
Rationale: Mitochondria are the major sites of aerobic cellular
respiration and oxidative phosphorylation. They use energy from
nutrients to generate ATP, the cell's principal energy currency. The Golgi
modifies and packages proteins, lysosomes digest cellular materials,
and the nucleolus produces ribosomal components.
3. Which molecule carries genetic information from DNA to the
ribosome for protein synthesis?
A. tRNA
B. rRNA
C. mRNA
D. ATP
Answer: C. mRNA
,Rationale: Messenger RNA (mRNA) is transcribed from DNA and carries
the genetic instructions to ribosomes, where the sequence is translated
into a protein. Transfer RNA delivers amino acids, while ribosomal RNA
forms an important structural and catalytic component of ribosomes.
4. Which process produces two genetically identical daughter cells?
A. Meiosis
B. Binary fission
C. Mitosis
D. Crossing over
Answer: C. Mitosis
Rationale: Mitosis involves nuclear division that generally produces two
genetically similar daughter cells with the same chromosome number as
the parent cell. Meiosis produces genetically varied haploid cells, while
crossing over is a genetic recombination event during meiosis.
5. During which stage of the cell cycle is DNA replicated?
A. G₁ phase
B. S phase
C. G₂ phase
D. M phase
Answer: B. S phase
, Rationale: DNA synthesis occurs during the S, or synthesis, phase of
interphase. G₁ involves cell growth and normal cellular activities, G₂
prepares the cell for division, and M phase includes mitosis and
cytokinesis.
6. Which structure contains the cell's chromosomes in a typical
eukaryotic cell?
A. Ribosome
B. Lysosome
C. Nucleus
D. Centriole
Answer: C. Nucleus
Rationale: In eukaryotic cells, chromosomes are housed within the
membrane-bound nucleus. The nucleus protects and organizes DNA and
regulates gene expression. Prokaryotic cells lack a membrane-bound
nucleus.
7. What is the movement of water across a selectively permeable
membrane called?
A. Diffusion
B. Osmosis
