Selected MCQ

Current Question
Which of the following organelles is present in plant cells but absent in animal cells?
  • A. Peroxisome
  • B. Centrosome
  • C. Chloroplast
  • D. Golgi apparatus
Correct Answer: C
Explanation:
Chloroplasts (sites of photosynthesis) are found in plant and algal cells but not in animal cells.
Related Question 1
Which organelle in animal cells contains its own circular DNA and is involved in ATP production?
  • A. Mitochondrion
  • B. Golgi apparatus
  • C. Peroxisome
  • D. Endoplasmic reticulum
Correct Answer: A
Explanation:
Mitochondria have a circular genome and produce ATP through oxidative phosphorylation.
Related Question 2
Gap junction channels between animal cells are formed by which protein?
  • A. Connexin
  • B. Cadherin
  • C. Integrin
  • D. Actin
Correct Answer: A
Explanation:
Connexins assemble into connexons that align between adjacent cells to form gap junction channels for direct cytoplasmic communication.
Related Question 3
Which of the following best describes clathrin function in eukaryotic cells?
  • A. It mediates the transport of proteins from the ER to the Golgi.
  • B. It forms a coat around vesicles during receptor-mediated endocytosis.
  • C. It phosphorylates tyrosine residues in signaling receptors.
  • D. It generates a proton gradient in endosomes.
Correct Answer: B
Explanation:
Clathrin polymerizes into a lattice on the inner surface of the plasma membrane, forming coated pits and vesicles that internalize receptors and ligands.
Related Question 4
A mutation prevents dynein from binding microtubules in eukaryotic cells. Which of the following processes would be most directly impaired?
  • A. Skeletal muscle contraction
  • B. Movement of vesicles from the Golgi apparatus to the endoplasmic reticulum
  • C. Movement of chromosomes toward the spindle poles during mitosis
  • D. Sliding of microtubule doublets in eukaryotic cilia and flagella
Correct Answer: D
Explanation:
Dynein motor proteins drive the sliding of microtubule doublets in cilia and flagella. Without functional dynein, ciliary and flagellar motion would be impaired. (Other processes involve myosin or different motor proteins.)
Related Question 5
Which of the following best describes polygenic inheritance?
  • A. One gene affects multiple traits (e.g., pleiotropy)
  • B. Many genes contribute to one trait (e.g., skin color)
  • C. A trait determined by genes only on the X chromosome
  • D. Inheritance of mitochondrial DNA
Correct Answer: B
Explanation:
Polygenic inheritance means multiple genes (often with additive effects) determine a single phenotype, such as height or skin color, producing continuous variation.