Test: Structure of Chromosomes - Class 10 MCQ

The G1 Phase of the cell cycle is characterized by cell growth and normal metabolic activities. During this phase, the cell increases in size and synthesizes proteins that are necessary for DNA replication and cell division. It sets the stage for the subsequent phases of the cell cycle.

Heterosomes, also known as sex chromosomes, are responsible for determining the sex of an individual. In humans, this typically involves the X and Y chromosomes, where the presence of a Y chromosome typically indicates male sex, while its absence indicates female sex.

Prophase I of meiosis is distinct for the pairing of homologous chromosomes. This phase is critical for genetic recombination, where crossing over occurs, leading to genetic diversity in the resulting gametes.

"Haploid" refers to cells that contain one set of chromosomes (n). In meiosis, haploid cells are produced as a result of two rounds of division, allowing for genetic diversity during sexual reproduction.

The G2 Phase is when a cell continues to grow and prepares for mitosis. This preparation includes synthesizing proteins and organelles necessary for cell division, ensuring that the cell is ready to undergo karyokinesis and cytokinesis.

A nucleosome is the structural unit of chromatin, consisting of a segment of DNA wound around a core of histone proteins. This structure helps package DNA into a compact form, allowing it to fit inside the nucleus and play a role in gene regulation.

The primary difference is that mitosis occurs in somatic (body) cells, resulting in two identical diploid daughter cells, while meiosis occurs in gametes (sex cells) and results in four haploid daughter cells. This distinction is crucial for sexual reproduction and genetic variation.

The spindle apparatus is crucial for separating chromosomes during cell division. It consists of microtubules that attach to the centromeres of chromosomes and pull them apart to opposite poles of the cell, ensuring that each daughter cell receives the correct number of chromosomes.

Meiosis is the process that reduces the chromosome number from diploid (2n) to haploid (n). This reduction is critical for sexual reproduction, allowing for the formation of gametes that combine during fertilization to restore the diploid number.

Mitosis serves the essential role of producing two identical daughter cells from a single parent cell. This process is vital for growth, repair, and the replacement of worn-out cells in an organism, ensuring that each daughter cell retains the same chromosome number as the parent cell.

Autosomes are non-sex chromosomes that control various bodily functions and traits unrelated to sex determination. Humans have 22 pairs of autosomes, which carry genes that contribute to the overall phenotype of an individual.

Cytokinesis in animal cells involves the division of the cytoplasm and results in the separation of the cytoplasmic contents into two new daughter cells. This process follows karyokinesis and is essential for completing cell division.

Karyokinesis is the specific process that refers to the division of the nucleus during cell division, which occurs during mitosis and meiosis. It is followed by cytokinesis, where the cytoplasm of the cell divides, resulting in two separate cells.

Zygotene is not a phase of mitosis; rather, it is a sub-stage of Prophase I in meiosis where homologous chromosomes begin to pair. Mitosis consists of Prophase, Metaphase, Anaphase, and Telophase.

DNA replication occurs during the S Phase of interphase. This is a crucial step in the cell cycle as it ensures that each daughter cell will have an identical set of chromosomes after cell division. The replication process involves unwinding the DNA and synthesizing new strands complementary to the original ones.

During cytokinesis in plant cells, a cell plate forms at the equatorial plane, which eventually develops into the cell wall that separates the two daughter cells. This is different from animal cells, which form a cleavage furrow.

Crossing over is significant because it increases genetic variation among offspring. During this process, segments of DNA are exchanged between homologous chromosomes, resulting in new allele combinations that contribute to diversity in a population.

A key characteristic of interphase is that DNA is replicated during the S Phase. Interphase is primarily a preparatory phase for cell division, during which the cell undergoes growth and duplicates its genetic material to ensure accurate division.

The centromere is the region of a chromosome that holds sister chromatids together until they are separated during cell division. It plays a crucial role in ensuring that each daughter cell receives an identical set of chromosomes.

Meiosis II is analogous to mitotic division as it involves the separation of sister chromatids, similar to what occurs during mitosis. However, meiosis begins with haploid cells, while mitosis starts with diploid cells.