Test: Cell Cycle (June 8) - NEET MCQ

The diploid cells found in the G₀ and G₁ phase before starting the G₂ or M phase but before anaphase. Cells with twice the normal DNA is in G₂ or M phase that is mitosis phase. The S phase is characterized by intermediate DNA when the DNA starts replicating itself, till the entire replication process is complete.

The phase in which cells fail to divide further (do not enter S- phase after G₁ -phase) and undergo differentiation is known as G₀ phase or quiescent stage. It occurs due to non availability of mitogen and energy rich compounds. The cells remain metabolically active, grow in size and differentiate for particular function after attaining a particular shape.

Interphase in a cell cycle has three stages —G₁,S and G₂.M− phase is not a part of interphase.

The cell cycle starts from interphase. Interphase is the phase in the cell cycle that prepare a cell and its nucleus for division. It has three stages- G_1​,S and G₂​. M- phase is the final phase of cell cycle..It represent the phase of actual division. It consists of karyokinesis (division of nucleus) and cytokinesis (division of cell protoplast).

S or synthesis phase marks the period during which DNA synthesis or replication takes place. DNA synthesis or replication takes place. During this time the amount of DNA per cell doubles, however, there is no increase in the chromosome number.

Replication of DNA along with the synthesis of nuclear proteins such as the histones occur during S phase of interphase.

Cell cycle consists of two basic phases, long non-dividing I phase and a short-dividing M phase. In the average duration of 24 hours in the cell cycle of a dividing human cell, M phase lasts for one hour (less than 5% of total ) while I phase or interphase occupies 75-95% of total generation time.

(i) Cell division is the process by which a cell divides to form to nearly equal daughter cell which resembles the parent. The cell cycle is the sequence of events which occur during the cell growth and cell division. It is completed into two steps interphase and M-phase.
(ii) In the cell cycle interphase is the period between the end of one division to the beginning of next cell division. It is known as the resting phase. In the case of human beings it is around 24 hours then the M phase takes place.

The cell cycle starts from interphase. Interphase is the phase in the cell cycle that prepares a cell nucleus for division. It has three stages — G₁, S and G₂ G₁, Phase is the longest stage of interphase, also first growth phase or post-mitotic gap phase. Both and its nucleus grow in size. There is synthesis proteins, nucleotides, amino acids for histones an rich compounds. In S-Phase chromosomes along with their DNAs replicate. DNA content doubles during this phase. In G₂-Phase there is increased synthesis of RNA and proteins. Cell organelles or their precursorsmultiply. Cell grows in Size.

• Yeasts are the saprophytic fungi that are found on the substrate which is rich in sugar.
• The vegetative reproduction takes place in yeast by budding or fission. Budding is a common method of reproduction in yeast under favourable condition. During this process, small bud-like outgrowth appears at one end of the parents yeast and then it falls off. Fission is a common method of reproduction during favourable condition and its nucleus divide into two daughter nuclei; the nucleus separation is then followed by cytokinesis. 
• Sexual reproduction takes place when the conditions are unfavourable. The cellular division in yeast takes place about in 90 minutes each.