Tag: division for growth and reproduction
Questions Related to division for growth and reproduction
Chromosome decondensation, crossing over synapsis formation, nucleolus disappear, chromosome separation, astral ray formation, centriole duplication. How many of these are observed in prophase of meiosis-1 and mitosis both?
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Three
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Four
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Two
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Five
Mitosis is equational division and meiosis is reductional division. Both consists of 4 phases, namely prophase, metaphase, anaphase and telophase. Prophase is the first phase of both mitosis and meiosis I. During this phase, the chromatin condenses and forms visible chromosomes. The mitotic spindle begins to form, nucleolus disappears, the nuclear envelope disappears.
The life of all multicellular organisms through sexual reproduction starts as a ............
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Zygote
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Sperm cell
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Haploid cell
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Egg
In sexual reproduction, an egg cell from female and a sperm from a male fuse to form a zygote, precursor to an embryo offspring. The offspring is generally distinct from parents. Both the gametes contain half the number of required chromosomes, that is they are haploid in nature. The zygote contains the exact number of chromosomes required. This is how chromosome number is conserved from generation to generation. The zygote undergoes further cell division to form an embryo.
What would be the DNA content of the cell at G1, G2, anaphase stage, when the content after the mitotic phase is 40pg
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G1=40 pg, G2=80 pg, anaphase= 40 pg
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G1=40 pg, G2=80 pg, anaphase= 80 pg
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G1=80 pg, G2=40 pg, anaphase= 40 pg
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G1=80 pg, G2=40 pg, anaphase= 80 pg
- In G$ _1$ phase the amount of DNA is the same as 40 because the cell is metabolically active but no division of DNA is observed.
- In G$ _2$ phase the DNA gets doubled as it has gone through the synthesis phase which is characterized by the replication of DNA.
- In mitosis since equational division occurs the DNA content remain 4C through the process before the transfer of DNA into daughter cells.
The most dramatic period of the cell cycle is
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M-phase
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$G _1$ phase
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$S$ phase
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Interphase
identify correct order of Eukaryotic cell...
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G1, G2, S, M ,cytokinesis
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G1, G2, M , S ,cytokinesis
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G1, M , G2 ,cyokinesis , S
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G1 , S , G2 ,M , cytokinesis
G$ _1$ , S , G$ _2$, M , cytokinesis. The correct sequence has G$ _1$ as a preparation for S and G$ _2$ as the time between the completion of S and entry into M. Cytokinesis occurs after the other stages to create two daughter cells.
Cell wall thickning and protoplasmic modification during growth of plants occur in ________________.
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Maturation phase
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Meristematic phase
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Elongation phase
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Secretory phase
In the maturation phase, the enlarged cells eventually acquire a specific size and form according to their location and role following biochemical, physiological and morphological changes, i.e., the cells undergo specialization or transformation. As a result, various kinds of cells get differentiated. These differentiated cells form different kinds of simple and complex tissues that perform different functions. This includes cell wall growth and protoplasm modification.
The stage of cell cycle when cell does not undergo differentiation is
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G$ _0$
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G$ _1$
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G$ _2$
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S$ _4$
The cell cycle mainly consists of 4 stages G$ _1$, S, G$ _2$, and M. The G$ _{0}$ phase also known as the extended G1 phase is a period in which the cell exits from the cell cycle. In this stage, the cell exists in a quiescent state and does not divide. Thus the correct answer is option A.
During cell cycle, RNA and protein synthesis takes place during which of the following phase?
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G$ _1$ and G$ _2$ phase
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S phase
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M phase
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Cytokinesis
During the cell cycle, RNA and protein synthesis takes place during G$ _1$ and G$ _2$ phase. The cell cycle is an ordered set of events, culminating in cell growth and division into two daughter cells. Non-dividing cells not considered to be in the cell cycle. The stages are G$ _1$-S-G$ _2$-M.
The sequence of cell cycle is
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S,M,G$ _{1}$, and G$ _{2}$
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G$ _{1}$,G$ _{2}$,S and M
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G$ _{1}$,S,$G _{2}$, and M
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M,G$ _{1},$,G$ _{2}$ and S
- Cell enters cell cycle at G$ _1$ (First Gap) phase, where the cell grows larger, doubles organelles and synthesizes proteins, enzymes and all other biochemical molecules required for efficient completion of cell division.
- Then cell enters S (synthesis) phase, where cell synthesizes a complete copy of the genomic DNA inside the nucleus. It also duplicates centrosome which is required for separation of DNA to opposite poles during mitosis.
- Then cell enters the G$ _2$ (Second Gap) phase, where cell grows more and produces more proteins and organelles required for mitosis. Cell also reorganize its contents for mitosis to occur. G$ _2$ phase also acts as a checkpoint to ensure that the cell is ready for mitosis.
- The end of G$ _2$ phase is the beginning of M (Mitosis) phase, where the real cell division occurs. The cell divides its doubled DNA and cytoplasmic contents to form two daughter cells.
The various phases of the cell cycle will be affected by limiting growth factors like
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Sufficient nucleotides
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Temperature
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Nutrients
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All of the above
G1 phase and the other subphases of the cell cycle may be affected by limiting growth factors such as nutrient supply, temperature, and room for growth. Sufficient nucleotides and amino acids must be present in order to synthesize mRNA and proteins. Physiological temperatures are optimal for cell growth. In humans, the normal physiological temperature is around 37 C. Therefore, the correct answer is option D.