All Free Biology MCQs with Answers

• A. Telomere
• B. Kinetochore
• C. Primary constriction
• D. Secondary constriction

Explanation: The centromere has special area known as kinetochore which is formed a special protein.

• A. Prophase
• B. Telophase
• C. Anaphase
• D. Metaphase

Explanation: The most critical phase of mitosis is anaphase.It is the most critical phase of the mitosis, which ensures equal distribution of chromatids in the daughter cells. The kinetochore fibers of spindle contract towards their respective poles, at the same time polar microtubules elongates exert force and sister chromatids are separated from centromere. As a result, half sister chromatids travel towards each pole. By precisely distributing chromosomes, anaphase guarantees that the two daughter cells formed at the end of mitosis are genetically identical to the parent cell. In essence, the orderly separation of chromosomes during anaphase is fundamental to the successful and accurate completion of mitosis, which is essential for growth, tissue repair, and overall organismal health.

• A. Prophase, Metaphase
• B. Anaphase, Telophase
• C. Metaphase, Anaphase
• D. Prophase, Telophase

Explanation: Reaching of the chromosomes at opposite poles terminates anaphase and start telophase.

• A. Crossing over
• B. Mitosis
• C. Meiosis
• D. Binary fission

Explanation: Regeneration, healing of wounds, and replacement of older cells are all the gifts of mitosis. Mitosis is a type of cell division that produces two identical daughter cells from a single parent cell. This process is essential for growth, repair, and reproduction.

• A. Chiasmata
• B. Recombination
• C. Crossing over
• D. Mutation

Explanation: The exchange of segments between non-sister chromatids of homologous chromosomes during meiosis is called crossing over. This process is responsible for genetic variation, as it can lead to the creation of new combinations of genes on the chromosomes.

• A. Telomere
• B. Kinetochore
• C. Primary constriction
• D. Secondary constriction

Explanation: A disc-shaped protein structure within the centromere to which the spindle fibers attached during mitosis or meiosis called the kinetochore. Kinetochores are large protein assemblies that connect chromosomes to microtubules of the mitotic and meiotic spindles in order to distribute the replicated genome from a mother cell to its daughters. The kinetochore is a protein structure that assembles at the centromere's surface, forming the site for binding spindle fibers during cell division.

• A. Monovalent
• B. Bivalent
• C. Tetravalent
• D. Pentavalent

Explanation: The first essential phenomenon of meiosis i.e. pairing of homologous chromosomes called synapsis starts. This pairing is highly specific and exactly pointed but with no definite starting points. Each paired but not fused, complex structure is called bivalent or tetrad. Bivalent is formed during zygotene. Each bivalent is made up of four chromatids, two of each chromosome. The centromere is the part of a chromosome that attaches to the spindle during cell division. Each bivalent, thus, contains two centromeres.

• A. Prophase I
• B. Metaphase I
• C. Anaphase I
• D. Telophase I

Explanation: The kinetochore fibers contract and the spindle or pole fibers elongate, which pull the individual chromosomes (each having two chromatids) towards their respective poles. The sister chromatids of each chromosome, however, remain attached and don't come apart.

• A. Spore formation in plants
• B. Sex cell formation
• C. Healing of wounds
• D. Gametes formation in animals

Explanation: Some organisms, both plants and animals, undergo asexual reproduction. Regeneration, healing of wounds and replacement of older cells all are the gifts of mitosis while Meiosis usually takes place at the time of sexual cell (gamete) formation, spore formation in plants.

• A. Recombinant
• B. Synapsis starts
• C. Tetrad
• D. Bivalent

Explanation: The first essential phenomenon of meiosis i.e. pairing of homologous chromosomes called synapsis starts. This pairing is highly specific and exactly pointed but with no definite starting points. It allows the matching-up of homologous pairs before their segregation, and possible chromosomal crossover between them.