CBSE Questions for Class 11 Medical Biology Cell Cycle And Cell Division Quiz 13 - MCQExams.com

• The fibres that are formed in between the centromeres of the homologous chromosomes are interzonal fibres. 
• Chromosomes are lined up on the equator of shaft in Metaphase. These are then separated into a frame of appendages with different shapes in Anaphase. 
• Thus, Interzonal fibres is seen between Metaphase to Anaphase. Option B is correct.

• According to this question, the size of the cell matters. Actually the ratio of the volume of the nucleus to the volume of cytoplasm which is nucleocytoplasmic ratio increases in the large cell or the cell undergoing growth only in G1 phase.

• 5 chromosome pairs mean 10 chromosomes.
• Each chromosome consists of two chromatids.
• In anaphase, the chromosomes get split into individual chromatids which act as individual chromosomes.
• So, in anaphase, a cell will have 20 chromosomes.

A. Anaphase – Contraction of spindle fibres takes place, division of centromere occurs, daughter chromosomes move towards the poles.

B. Prophase – condensation of chromosomes occur. Chromosomes thick, short.

C .Metaphase – Metaphasic or equatorial plate is formed.

D. Telophase – Decondensation of chromosomes takes place. Chromosome elongated and their length increases.

The correct answer is $$(A)$$.

Wheat is an angiosperm plant. In this plant $$80$$ grains (seeds) are produced by fertilization between $$80$$ male and $$80$$ female gametes. $$80$$ male gametes therefore, pollen grains are produced by $$20$$ meiosis in microspore mother cells while $$80$$ female gametes therefore, megaspores are formed by $$80$$ meiosis in megaspores mother cells because in angiosperm plants, after meiotic division in single megaspore mother cell, four megaspores are formed but only one megaspore is survived and other three get degenerated. Thus total meiotic divisions are $$20 + 80 = 100$$.

So, the correct option is '100'.

• Spindle fibers form a protein structure that divides the genetic mateial in a cell.
  
• The spindle is necessary to equally divide the chromosomes in a parental cell into two daughter cells during both types of nuclear division: mitosis and meiosis.

• Meiosis is a type of cell division that reduces the number of chromosomes present in the parent cell by half and produces four gamete cells. 
• This process is required to produce egg and sperm cells for sexual reproduction. 
• Meiosis begins with a parent cell that is diploid, meaning it has two copies of each chromosome. The parent cell undergoes one round of DNA replication followed by two separate cycles of nuclear and cytoplasmic division. 
• The process results in four daughter cells that are haploid, which means they contain half the number of chromosomes of the diploid parent cell.

So, the correct option is '4 Haploid cells'.

• In telophase, the two chromosomes elongate and overlap one another to form chromatin. A nuclear envelope appears on its outside from pieces of the older nuclear envelope and annulated endoplasmic reticulum. The golgi complex and endoplasmic reticulum are reformed.
• In prophase, the condensation of chromosomal material. The chromosomal material becomes untangled during the process of chromatin condensation. Chromosomes are seen to be composed of two chromatids attached together at the centromere.
• In metaphase, the spindle fibres are attached to the kinetochores of chromosomes. Chromosomes are moved to the spindle equator and get aligned along with the metaphase plate through spindle fibres to both poles.
• So, the correct answer is option A.

• During cell cycle a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells. All other constituents of cell can also be synthesized during this phase.

• There are three phases of interphase, G$$_1$$, S and G$$_2$$ phase. 
• In G$$_1$$ phase cell organelles do not increase in number. The cell grows in size but the growth of nucleus is little. 
• In S phase, duplication of DNA material takes place.
• In G$$_2$$ phase, the cell organelles increase in number. Both cell and nucleus grow in size. 

• Mitosis is a process of nuclear division in eukaryotic cells that occurs when a parent cell divides to produce two identical daughter cells. 
• Each time number of cells double like this