Tahsili Biology — Questions and Answers
Question 1: What is the function of mitochondria in a cell?
- Protein synthesis
- Cellular respiration — producing ATP (energy) through oxidative phosphorylation (Correct answer)
- Photosynthesis
- Cell division
Correct answer: Cellular respiration — producing ATP (energy) through oxidative phosphorylation
Mitochondria are the 'powerhouses of the cell,' producing ATP through cellular respiration (glycolysis, Krebs cycle, electron transport chain). They convert glucose and oxygen into ATP, CO₂, and water.
Question 2: What is the complementary DNA strand for the sequence 5'-ATCGGA-3'?
- 3'-ATCGGA-5'
- 3'-TAGCCT-5' (Correct answer)
- 5'-TAGCCT-3'
- 3'-UAGCCU-5'
Correct answer: 3'-TAGCCT-5'
DNA base pairing: A pairs with T, C pairs with G. The complementary strand runs antiparallel (3' to 5'): A→T, T→A, C→G, G→C, G→C, A→T = 3'-TAGCCT-5'.
Question 3: What is the role of ribosomes in protein synthesis?
- Storing genetic information
- Reading mRNA and assembling amino acids into proteins (translation) (Correct answer)
- Transcribing DNA to RNA
- Packaging proteins for export
Correct answer: Reading mRNA and assembling amino acids into proteins (translation)
Ribosomes are the site of translation — they read the mRNA codon sequence and assemble the corresponding amino acids into polypeptide chains. Ribosomes consist of a large and small subunit made of rRNA and proteins.
Question 4: What is meiosis and what is its significance?
- Cell division producing identical cells
- Cell division producing four genetically unique haploid gametes, enabling sexual reproduction and genetic diversity (Correct answer)
- Cell growth without division
- DNA replication only
Correct answer: Cell division producing four genetically unique haploid gametes, enabling sexual reproduction and genetic diversity
Meiosis involves two divisions (meiosis I and II) producing four haploid gametes (n) from one diploid cell (2n). Genetic diversity is generated through crossing over, independent assortment, and random fertilization. Essential for sexual reproduction.
Question 5: What is the difference between genotype and phenotype?
- They are the same thing
- Genotype is the genetic makeup (alleles); phenotype is the observable physical characteristics (Correct answer)
- Genotype is appearance; phenotype is DNA
- Genotype applies to plants; phenotype to animals
Correct answer: Genotype is the genetic makeup (alleles); phenotype is the observable physical characteristics
Genotype refers to the specific alleles an organism carries (e.g., Bb for brown eyes). Phenotype is the observable expression of those genes (e.g., brown eyes). Phenotype results from genotype + environmental influences.
Question 6: What is the process of photosynthesis?
- Breaking down glucose for energy
- Converting light energy, CO₂, and H₂O into glucose and O₂ using chlorophyll (Correct answer)
- Absorbing oxygen and releasing carbon dioxide
- Converting proteins into carbohydrates
Correct answer: Converting light energy, CO₂, and H₂O into glucose and O₂ using chlorophyll
Photosynthesis: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. It occurs in chloroplasts using chlorophyll to capture light energy. The light reactions produce ATP and NADPH; the Calvin cycle fixes CO₂ into glucose.
Tahsili Biology
What is the function of mitochondria in a cell?