COMPREHENSIVE BIOLOGY
QUESTIONS AND ANSWERS FOR
STUDENTS
1. WHAT IS THE CELL THEORY, AND WHAT ARE ITS
MAIN PRINCIPLES?
Answer:
The cell theory is a fundamental biological concept stating that:
1. All living organisms are composed of cells—either unicellular or
multicellular .
2. The cell is the basic unit of life—all life processes occur within cells.
3. All cells arise from pre-existing cells; they do not spontaneously
generate.
Additional Notes: Proposed by Matthias Schleiden and Theodor Schwann in 1839,
later expanded by Rudolf Virchow.
2. EXPLAIN THE DIFFERENCE BETWEEN
PROKARYOTIC AND EUKARYOTIC CELLS.
Answer:
Feature Prokaryotic Cells Eukaryotic Cells
No true nucleus (DNA in
Nucleus Membrane-bound nucleus
nucleoid)
No membrane-bound
Organelles Has mitochondria, ER, Golgi apparatus, etc.
organelles
, Feature Prokaryotic Cells Eukaryotic Cells
Size Smaller (1-5 µm) Larger (10-100 µm)
Present in plants (cellulose), fungi (chitin);
Cell Wall Present (peptidoglycan)
absent in animals
Reproduction Binary fission Mitosis and meiosis
Examples Bacteria, Archaea Animals, Plants, Fungi, Protists
Key Takeaway: Prokaryotes are simpler and evolved earlier , while eukaryotes have
complex structures.
3. HOW DOES DNA REPLICATION ENSURE GENETIC
CONTINUITY?
Answer:
DNA replication is a semi-conservative process where each new DNA
molecule contains one original strand and one new strand.
Steps in DNA Replication:
1. Helicase unwinds the DNA double helix.
2. Single-strand binding proteins stabilize the strands.
3. Primase synthesizes RNA primers.
4. DNA polymerase III adds nucleotides in the 5’→3’ direction.
5. The leading strand is synthesized continuously; the lagging strand forms
Okazaki fragments.
6. DNA ligase joins Okazaki fragments.
Significance: Ensures genetic accuracy during cell division; errors can cause
mutations and disease.
4. WHAT IS PHOTOSYNTHESIS, AND WHAT ARE ITS
TWO MAIN STAGES?
Answer:
Photosynthesis is the process by which plants, algae, and some bacteria
convert light energy into chemical energy (glucose) using CO₂ and H₂O.
QUESTIONS AND ANSWERS FOR
STUDENTS
1. WHAT IS THE CELL THEORY, AND WHAT ARE ITS
MAIN PRINCIPLES?
Answer:
The cell theory is a fundamental biological concept stating that:
1. All living organisms are composed of cells—either unicellular or
multicellular .
2. The cell is the basic unit of life—all life processes occur within cells.
3. All cells arise from pre-existing cells; they do not spontaneously
generate.
Additional Notes: Proposed by Matthias Schleiden and Theodor Schwann in 1839,
later expanded by Rudolf Virchow.
2. EXPLAIN THE DIFFERENCE BETWEEN
PROKARYOTIC AND EUKARYOTIC CELLS.
Answer:
Feature Prokaryotic Cells Eukaryotic Cells
No true nucleus (DNA in
Nucleus Membrane-bound nucleus
nucleoid)
No membrane-bound
Organelles Has mitochondria, ER, Golgi apparatus, etc.
organelles
, Feature Prokaryotic Cells Eukaryotic Cells
Size Smaller (1-5 µm) Larger (10-100 µm)
Present in plants (cellulose), fungi (chitin);
Cell Wall Present (peptidoglycan)
absent in animals
Reproduction Binary fission Mitosis and meiosis
Examples Bacteria, Archaea Animals, Plants, Fungi, Protists
Key Takeaway: Prokaryotes are simpler and evolved earlier , while eukaryotes have
complex structures.
3. HOW DOES DNA REPLICATION ENSURE GENETIC
CONTINUITY?
Answer:
DNA replication is a semi-conservative process where each new DNA
molecule contains one original strand and one new strand.
Steps in DNA Replication:
1. Helicase unwinds the DNA double helix.
2. Single-strand binding proteins stabilize the strands.
3. Primase synthesizes RNA primers.
4. DNA polymerase III adds nucleotides in the 5’→3’ direction.
5. The leading strand is synthesized continuously; the lagging strand forms
Okazaki fragments.
6. DNA ligase joins Okazaki fragments.
Significance: Ensures genetic accuracy during cell division; errors can cause
mutations and disease.
4. WHAT IS PHOTOSYNTHESIS, AND WHAT ARE ITS
TWO MAIN STAGES?
Answer:
Photosynthesis is the process by which plants, algae, and some bacteria
convert light energy into chemical energy (glucose) using CO₂ and H₂O.
