All Free Biology MCQs with Answers

• A. S phase
• B. Prophase
• C. Interphase
• D. G0

Explanation: Prophase is the first stage of mitosis, where chromatin condenses into visible chromosomes, the nuclear envelope breaks down, and the mitotic spindle begins to form. Additionally, centrosomes move to opposite poles of the cell, and spindle fibers start to extend from them towards the chromosomes. Prophase marks the beginning of the process of cell division and is characterized by significant changes in the organization of cellular structures in preparation for chromosome segregation.

• A. Interphase, prophase, metaphase, anaphase, telophase
• B. Prophase, metaphase, anaphase, telophase
• C. Interphase, prophase, metaphase, telophase
• D. None of the above

Explanation: Explanation for this question will be added soon!

• A. It duplicates the DNA
• B. It divides the cell in half
• C. It helps separate the chromosomes
• D. It provides energy

Explanation: The kinetochore serves as the attachment point for spindle microtubules, facilitating the movement and alignment of chromosomes during cell division. It regulates the tension and attachment stability between the chromosomes and the spindle apparatus, ensuring accurate segregation of genetic material. Additionally, kinetochores signal the cell cycle checkpoints to ensure proper progression through mitosis and prevent errors in chromosome segregation. Thus, kinetochores play a critical role in orchestrating the precise and orderly division of cells.

• A. Chromatin
• B. Centrioles
• C. Phragmoplast
• D. Contractile ring

Explanation: Recent research suggests that while centrioles are absent in some animal cells during interphase, they may still be present in modified forms or functionally equivalent structures. Additionally, some animal cells, like those in certain tissues or developmental stages, may lack centrioles altogether. This diversity reflects varying cell requirements and evolutionary adaptations rather than a universal absence of centrioles during cell division in animal cells.

• A. Spindle fibers
• B. Size
• C. Growth rate
• D. Shape

Explanation: Explanation for this question will be added soon!

• A. Connective
• B. Muscle
• C. Epithelial
• D. Spongy

Explanation: Epithelial tissue primarily lines surfaces exposed to the external environment or internal cavities with direct openings to the outside. Internal organs are typically surrounded by connective tissue and are not directly exposed to the external environment, thus they don't require a lining of epithelial tissue. Instead, the epithelium serves as a protective barrier for surfaces where absorption, secretion, and exchange of substances occur. Therefore, organs are often encapsulated within the body and do not necessitate direct epithelial lining.

• A. Nerve
• B. Connective
• C. Muscle
• D. Joints

Explanation: Skeletal muscle tissue enables finger movement when playing the piano by contracting and relaxing in response to signals from the nervous system, allowing precise control and coordination of finger motions essential for playing melodies and chords accurately.

• A. Condensation → Nuclear membrane disassembly → Arrangement at equator → Centromere division → Segregation → Telophase
• B. Condensation → Arrangement at equator → Centromere division → Segregation → Telophase
• C. Condensation → Nuclear membrane disassembly → Crossing over → Segregation → Telophase
• D. Nuclear membrane disassembly → Condensation → Arrangement at equator → Segregation → Centromere division → Telophase

Explanation: Mitosis is divided into four phases, i.e., prophase, metaphase, anaphase, and telophase. During prophase, the indistinct and intertwined DNA molecules condense to form elongated chromosomes. The nuclear membrane disintegrates during prophase. During metaphase, the chromosomes align themselves at the equatorial plate. During anaphase, the centromere of each chromosome divides into two so that each chromosome comes to have its own centromere. Chromatids move towards opposite poles along the path of their chromosome fibers. Finally, during telophase, two chromosome groups reorganize to form two nuclei. The nuclear envelope reappears, the Golgi complex and endoplasmic reticulum are reformed, etc. Crossing over occurs during meiosis. Option (c) also gives the correct sequence of events, but it misses step II (nuclear membrane disassembly). Hence, it is ruled out, as the most appropriate answer is answer (a).

• A. Chromosomes will be fragmented
• B. Chromosomes will not segregate
• C. Recombination of chromosome arms will occur
• D. Chromosomes will not condense

Explanation: During anaphase in mitosis, sister chromatids segregate at opposite poles. Therefore, a defective APC will affect chromosome segregation.A defective APC can have detrimental consequences for the proper functioning of mitosis and the cell cycle. It can lead to a range of issues, including genomic instability, aneuploidy, cancer development, and cell death, ultimately affecting the overall health and functionality of an organism. The specific effects may vary depending on the extent and nature of the APC defect.

• A. A­(iii), B­(iv), C­(ii), D­(i)
• B. A­(i), B­(iv), C­(ii), D­(iii)
• C. A­(ii), B­(iv), C­(iii), D­(i)
• D. A­(iv), B­(iii), C­(ii), D­(i)

Explanation: Pachytene: Crossing­over takes place.Metaphase I: Chromosomes align at equatorial plate.Diakinesis: Terminalisation of chiasmata.Zygotene: Pairing of homologous chromosomes.