All Free Biology MCQs with Answers

• A. Attach chromosomes
• B. Separate chromosomes
• C. Align chromosomes
• D. All of the above

Explanation: Specialized microtubules structures including aster and spindle which form by centrioles in animals cells are called the mitotic apparatus. Mitotic apparatus is a temporary structure in a dividing cell that enables the chromosomes to move to the poles of the cell thus ensuring their even distribution between the daughter cells.

• A. Prophase, metaphase
• B. Anaphase, telophase
• C. Metaphase, anaphase
• D. Telophase, interphase

Explanation: Anaphase is the critical microtubules phase of cell division which ensures equal distribution of chromatids in the daughter cells. In anaphase, chromosomes get separated (due to division of centromere) and move to opposite poles. This terminates anaphase and now early telophase starts in which the nuclear membrane and nucleolus reappear while chromosomes decondense to form Chromatin.

• A. Metaphase
• B. Early telophase
• C. Anaphase
• D. Prophase

Explanation: At cytokinesis, in place of the contractile ring membrane structure, a phragmoplast is formed from vesicles that originate from the Golgi complex in plant cells. These vesicles originate during metaphase and line up in the centre of the dividing cell, where they fuse to form a phragmoplast at the end of telophase.

• A. Nuclear membrane
• B. Mitotic apparatus
• C. Nucleoli
• D. None of these

Explanation: The telophase of mitosis is opposite to the prophase. Hence, in telophase, the mitotic apparatus is disorganized, the nucleolus and nuclear membrane reappear and chromosomes become uncondensed to form chromatin.

• A. Two divisions
• B. Two interphases
• C. Four daughter cells
• D. Two times replication

Explanation: Meiosis is a type of cell division in which chromosome duplication only occurs once during meiosis I, while there is no replication in second meiotic division due to the absence of S-phase.

• A. Zygotene
• B. Diplotene
• C. Pachytene
• D. Diakinesis

Explanation: In the Zygotene, homologous chromosomes start pairing which completes in the pachytene, where crossing over occurs. In diplotene, these paired chromosomes repel each other and begin to separate. The separation of homologous chromosomes is still not complete because chromosomes remain united by chiasmata. Separation of homologous completes in anaphase 1.

• A. Chromatids
• B. Bivalents
• C. Chromosomes
• D. Centrioles

Explanation: Metaphase 1 of meiosis I is characterized by the disorganization of the nuclear membrane. Spindle fibers originate and the kinetochore libers attach to the kinetochore of homologous chromosomes from each pole and arrange bivalents at the equator.

• A. Gametogenesis
• B. Fertilization
• C. Sporogenesis
• D. Development

Explanation: During gametogenesis, in animals and sporogenesis in plants, chromosome numbers reduce to half, which on fertilization again restore.

• A. Prophase 1
• B. Anaphase 1
• C. Metaphase 1
• D. Anaphase 2

Explanation: Anaphase 1 of meiosis I is the actual reduction phase because each pole receives half of the total number of chromosomes.

• A. Prophase 1
• B. Prophase 2
• C. Anaphase 1
• D. Anaphase 2

Explanation: During anaphase II, sister chromatids of each chromosome separate and move toward opposite poles. The centromeres separate and the sister chromatids, now individual chromosomes, move toward the opposite poles of the cell