Tag: tissues of animals

People with type O- negative blood are the universal donor for the whole blood. That means that, anyone can receive this blood type. Being O- negative, this blood group is compatible with all the blood groups, A${^+}$and A${^-}$ve, B${^+}$ve, B${^-}$ve, and AB${^+}$, AB${^-}$ve. And the chances of rejection is the least.
Therefore, the correct answer is option D.

The blood group found in human beings are of four principal types: A, B, AB and O. These types are differentiated on the basis of two antigens A and B and two antibodies A and B present in the blood types. The specific combination of antigens and antibodies determines an individual's blood type. A person with blood group O has no antigen on the surface of the RBC but has both, anti- A and anti- B antibodies in his plasma.

In mitosis DNA content is doubled during S phase resulting in 2n chromosomes having two chromatids. These 2 chromatids of 2n get arranged at metaphase plate in metaphase. And in anaphase, the 2 chromatids of 2n chromosomes are separated from each other . so the cell during this phase becomes 4n.

Early in the history of biology, scientists believed cells arose spontaneously. With the development of cell theory, people finally realized that only cells can beget other cells. In fact, two categories that define something as living or not are growth and reproduction, both of which cell division accomplishes. Cell division, also called mitosis, occurs in all living things. As living things grow, some cells die or become damaged and need replacements. Some single-celled organisms use a type of mitosis as their only form of reproduction. In multicellular organisms, cell division allows individuals to grow and change by expanding the number of total cells. The division of the nucleus is equal during cell division. This ensures the characteristic of both parent cell in daughter cells and restores the size of the nucleus.

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. 

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. 

1. 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.
   
2. In G$ _2$ phase the DNA gets doubled as it has gone through the synthesis phase which is characterized by the replication of DNA.
3. In mitosis since equational division occurs the DNA content remain 4C through the process before the transfer of DNA into daughter cells.

So the correct option is "G$ _1$=40 pg,G$ _2$=80 pg,anaphase=80pg"

Mitotic or M- phase is the most dramatic period of the cell cycle is involves in major reorganisation of virtually all components of the cell.

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.

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.