Answer:
Cell of and integument
Explanation:
When flowering plants reproduce by sexual reproduction, they form seeds contained into fruits. The fruit is derived from the maturation of the flower's ovary (female part) after fertilization.
A mature seed contains three generations:
- a diploid embryo (the new sporophyte),
- The embryo is surrounded by haploid female gametophyte tissue that supplies nutrition
- All the above structure is in turn surrounded by the seed coat (diploid parental sporophyte tissue). The seed coat is produced by integument cells to protect the embryo during its development and before its can germinate. As it is produce by it parental plant, its ploidy level diploid.
In contrast, the generative nucleus and sperm cell are part of male gametophyte (pollen grain) and therefore haploids. Synergid cell is part of embryo sac, therefore belongs to female gametophyte and thus being haploid. Finally, cell of endosperm is usually derived from the fusion between a sperm cell and one of the two female gametes present within the embryo sac, thus being triploid.
Answer:
The two important conditions that must be met before gram staining are-
1. The age of the culture should not exceed 24 hours.
2. Over heating, decolonization should be avoided.
Explanation:
Gram staining is a technique developed to distinguish the bacteria on the basis of the composition of the cell wall around the bacteria.
The gram stain is a sensitive technique so must be performed carefully. The precautions should be taken to avoid any error while gram staining that is-
1. Age of the culture- The culture should be freshly prepared just 18-24 hours before the experiment as above 24 hours bacteria lose their ability to retain the color so one would not be able to differentiate between the cultures.
2. While performing the experiment one should avoid overheating and decolorization with ethanol as both the factors lead to the loss of crystal violet stain from the cell and they take pinkish color after safranin staying.
Topography is the rise and fall of the land (AKA B)
The things with winter and overnight freeze are that this change of the weather can seriously harm the crop and do irreversible damage.
To prevent this, farmers use some methods.
One is the usage of heaters, not allowing the freeze to set.
Another one is to spray the crop with water before the predicted overnight freeze. When water freezes and turns into ice, it releases latent heat. Then, the ice that builds upon the plant will insulate it from the colder surrounding air temperatures.
- Xylem contains tracheids, vessels, xylem parenchyma and xylem fibre.
- Tracheids: They are elongated, tubular dead cells with tapering end walls.
- Vessels: These are also known as trachea. They are elongated, tubular dead cells. They are joined to each other by end to end forming a continuous pipe. The cells are thick and lignified.
- Xylem parenchyma: They are also called wood parenchyma. This is the only living tissue of xylem.
- Xylem fibre: They are dead cells with thick walled fibre.
- Phloem consists of sieve tubes, companion cells, phloem parenchyma and phloem fibres.
- Sieve tubes: These are elongated, tubular living cells arranged in a row, with their perforated end walls forming a sieve. They are non-nucleated. Their protoplasm are inter-connected through sieve plates. They possess vacuoles.
- Companion cell: They are elongated, lens-shaped cells containing dense cytoplasm and prominent nuclei. These cells maintain connection with sieve cells through pits.
- Phloem parenchyma: They are living thin walled parenchyma cells.
- Phloem fibre: They are also known as bast fibre. They are elongated fibre like sclerenchymatous dead cells with thick walls containing pits and interlocked ends. Phloem fibre are the only dead cells in phloem.
Hope you could get an idea from here.
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